My first VCR was a 6 head that i bought in 1987? (i think). Their big selling point was the heads were "glass encapsulated." All i know is i gifted that VCR to my parents at one point, and it was still working over 20 years later. Of course, they were not heavy VCR users, but still.
42:12 - The head on the left is the *audio* erase head. This was used if one wanted to 'dub' audio onto the tape; it would erase the audio track without erasing the video. The full-width erase head is located 'upstream' from the video heads (to the left of the mechanism). The only VCR that I've seen with this 'dub' feature was my Quasar model from 1979.
The "some sort of hall effect sensor" is actually a grounding brush to discharge the static generated by the tape moving over the spinning upper drum assembly.
I did TV and VCR repairs in the mid-ninties in the UK. You had to do some alignment adjustments, of course, but the heads, in fact the head drum, were indeed replaceable. You could get new head rums or rebuilt drums from specialist suppliers, such as CPC in the UK, which were much more economic and in some cases better than the originals! Not cheap, typically £30-60 with original Sony heads being significantly more expensive. The alignment of the heads on the drum is critical and done under specilist microscpes, so you get a complete upper drum, not the heads themselves. They were wired in pairs, either in series or parallel so a fully stuffed head drum had to have three rotating transformer coils, one for the basic two heads, one for the extra pair on a four head machine and one for the Hifi track if fitted. The tape baskets were indeed srevice replaceable. When people tried to get a tape out by force, the basket often got bent such that replacement was the only fix. Quite expensive but generally a pretty easy fix. You could get belt and service kits for practically all deck families. Some decks were complex and a nightmare for repairs, such as the Panasonic J deck, one of the very few I had to get a proper service manual for as it had just one motor to do everything and loads of gears which had to be carefully synchronised - they had holes and the service manual was nigh on essential to getting the gear realignment right, after, say, replacing the tape basket. Lots of VCR makers bought decks in and put them in their own VCRs. One common OEM deck make used by many low cost VCR makers was Goldstar who at the time was almost an unknown in the UK. In the mid-ninties, about the time I got out of the repairs game, they changed their name to "Lucky Goldstar" or LG...
Years ago I took apart an older VCR, then months later a much newer VCR. The difference was night and day, with the newer one built right down to a cost. Thin stamped sheet stock, lots of plastic, motors doing multiple tasks instead of there being multiple motors. The older version was exquisitely built :D Cast aluminium body with lots of gears and belts, several motors, lots going on. It was incredible seeing it in operation and every part of the mechanism working as you inserted a cassette and watched it spool up
I spent around 20 years working on VCRs and it was notable how the mechanisms became simpler and ultimately flimsier with cost reduction. Good times while it lasted, well, mostly!
The VCR is a fascinating device. A lot of mechanical parts designed to maximize the amount of tape path for the record/playback head. The video quality is poor compared to today's demands, but it's amazing to know how much data was actually being stored already on that VHS Adrian would have had a lot of fun digging through my old Zenith Beta. It was one of the early VCRs, and very large
@@CyranoJones509 indeed, I recall Gary Kildall talking at length in the late 80s how amazing it was that video was the equivalent to many gigabytes. He was especially focused on laserdisc, since it had random-access, but IIRC also discussed how VHS and Beta could be used for even larger offline backups.
@ I hadn't heard that before, but I do recall a board that allowed the Tandy 1000 (?) to use a VCR for a backup storage device For my own purposes, I discovered that a HiFi VCR served as an excellent music medium since each playback was synchronized to the timebase stored on the tape
@@CyranoJones509 it was while going through the Computer Chronicles backlog, alas that means I can’t point to one specific episode as there’s so many 😅 My dad had his VCR hooked up to his hifi (my older brother’s biker friend set it up) for playback but he only ever dubbed onto type-2 cassette, haha. It was for his car so it tracks, but, still lol
@@CyranoJones509Indeed! It was one of the most advanced mainstream electromechanical devices to grace our homes. Now all the wizardry is hidden in silicon, pushed beyond intuitive understanding that mere dismantling once revealed.
The capstan has a coil that produces a tone that is used to control the speed though a phased locked loop circuit. In a VCR everything has to be controlled just right
When I was like 7 or something I "fed" Lucky Charm marshmallows to my dad's VCR. It wasn't long until he used it and it didn't take very long for things to go wrong. Apparently it spent a couple weeks at a repair shop and the guy had to completely disassemble and clean all the components. It's a very nice model from the 70's and still works. Whenever the video/audio starts getting "trippy" from old worn out Christmas movies I joke about it having to do with the marshmallows.
I totally expected to see a bunch of fingers connecting to a multi layer centre post inside the video drum, so I was a bit surprised to see the induction setup. The reason is because I tore apart a very early model VCR some 25 years ago and I swear that's what I saw, but maybe I'm misremembering it. It was a JVC HR3300 rebadged as a Rank Arena, and it weighed a freakin ton. Obviously it was broken and my attempts to repair it failed, probably because I had no idea what I was doing back then, so I tore it all apart instead. Pretty sure I still have some of the one million machine screws in my random screws bin
Very old video tape recorders which used helical scan used that method, but by the time beta and vhs came out, they had switched to wireless rotary transformers. (Including the jvc 3300u.)
Philips VCC2000 recorders I worked on (ages ago) also had these transformers in their head drums. We were able to pick up scrapped recorders that had manufacturing defects and then combine the working parts from two or three of those into a working recorder. Then sold those for a friendly price to friends of ours 😊
Slip rings can be used, but are noisy, which is NOT good for signal integrity. Induction is a much better system, as there is no mechanical joint, just electromagnetic coupling.
Even an old video 2000 vcr maybe from 1980 or maybe older. Had induction to transfer the video signal. That whole thing was made of steel parts. Even the parts that stuck inside the tape to roll. The spools. Looked like it could make crater if you dropped it.
@34:34, That third unused coil is for Hi-Fi audio or a 'Flying Erase Head'... VHS HiFi audio is written inbetween the video tracks on a dedicated set of heads at an alternate azimuth to not interfere with the video tracks. A flying erase head is used in VCRs which allow frame accurate insertion recording. A fully featured VCR will have 4 coils for commutation of all the different head types. However, 4 head VCRs use only 2 main coils like the one you are showing. (Count the number of desoldered contacts you needed to do to lift off the top of the video head, is was 8, or 4 per side. If you were desoldering for a 2 head VCR, you would have desoldered 4 contacts, 2 on each side. However, when you go further into your head disassembly, you see only 2 coil contacts are soldered on each head meaning this is a 2 head VCR even though it the head drive was capable of handling the 4 contacts for a 4 head VCR) For the 4 head VCRs, the 2 heads you see on each side of the spinning video actually has 2 heads right up against each other with one head at a slightly alternate height so that when you pause the video tape, the current video frame field is displayed on the main head, but since the tape is no longer in motion, the alternate height head can pick up the same video track since it looses alignment along a motionless tape as the tape was recorded in motion. For 2 head VCRs, you only need a single coil with both heads tied in parallel. Remember, only 1 head is in contact with the tape at 1 time while the other head is open in mid air. Do not confuse HiFi VCR heads where you actually see 4 heads on the video head drum. Those VCRs usually have the 4 video heads for perfect freeze fame plus another 2 heads at a 90 degree offset for the HiFi audio. These VCRs actually have 6 heads.
This is the first time in my life that I've actually seen an explanation for what "4-head" really means on a VCR. Thanks for that. Makes perfect sense.
@@nickwallette6201 I did make 1 mistake in the above description, please excuse me as the last time I worked on a VCR was decades ago. 2 coils were used, 1 for each side of the playback heads. The reason for this is there is a little overlap on the video tape when playing back from choosing 1 head to the next. This offers a brief moment in time where the VRC electronics can perform a rapid switchover from 1 head on one side at the end of a video frame to the next head beginning actually right at the bottom of the picture, ready to begin the next frame. Without the rapid selection switch with 2 separate coils side of the video head, you will get a messy joint as 1 head begins to pickup the next part of the next frame. Especially as the video tape itself may begin to stretch over it's life or may have come from a slightly differently aligned VCR. If you had an old analog CRT monitor with an adjusted v-size where you could see the overscan of the video playback, you might get a glimps at the bottom of the picture a horizontal miss-alignment during this read head swap as your CRT may not adjust fast enough horizontally to capture the slight timing alignment during that swap. This bend does not exist on live cameras or professional broadcasts which have time-base-corrected analog video tape players or digital tape players.
If you don't have a digital microscope I highly suggest getting one for these kind of explorations as, even the cheap one's, can really show great detail of these teeny tiny components. Aside from a VCR mechanism, my other favorite one is the slot loading DVD drive in the GameCube compatible Wii systems as it could take both the standard 12cm optical disc but it could also accept the 8cm mini-DVDs that the GameCube used and it didn't matter where you inserted the mini DVD as it could automatically align it to the center. It was so cool the way the "arms" would sort of hug the disc to center it. So many parts working in unison for it to be able to accept GameCube disc. It would have been so much cheaper to use a standard tray or what the GameCube used.
I forgot to mention the Dehedral adjustment needed to center an upper head drum when replacing video heads. That adjustment was done to center the upper head drum on the lower head drum assembly. Also that edge you saw cut into the lower head drum assembly is a 'rabbit' that is a guide to control how the tape passes by the heads. After so many head hours, the lower head drum had to be replaced as the aluminum that the tape would touch passing by in playback or record, would get so the aluminum so smooth that the tape would stick to the drum (called slip-stiction) and lower head drums had to be completely replaced and are VERY expensive. The OEM would ship a fully aligned drum assembly for replacement and send back the old one for refurbishment. Ahh, the joy of tape-based video playback. Thanks again, Gerry
I can't tell you how many VCR's I took apart as a kid - they used to be very common trash items. I'd probably find one or three every year. Sometimes they would even still work. Those days are long gone, so thank you for showing this for all those in the future who won't get the chance!
I've always wondered how the connections were made on those spinning heads too. Now I know. Thanks! I enjoyed Tim Hunkin's 'The Secret Life of Machines' videorecorder episode from back in the 90s I think. It's available on RUclips.
I have done a lot of home machining, and that drum assembly, is truly a work of art. This was an enjoyable, educational video. I have a couple of the top of the line Thompson VCRs, that date back to the 80s, that I would like to make operational again. One of the units, just has a deteriorated belt, and I haven't taken the time to source a replacement. After watching this, I am motivated to get after it again. .
I have a VCR somewhere I tried to get in to 15 years ago after it had been had degraded video playback since like 2000 or so which had stopped working by like 2008. I think it really is just dry belts and tires. Honestly, it's probably easier to repair this sort of thing now, as far as like, finding belt kits and things for a specific model of VCR. If I was generally more motivated and less worried about breaking it more, I'd try to get in to it again. It was a nice VCR as far as I recall, though I know it has a lot of hours of recording TV and watching movies. Who knows, maybe it's full of blown caps at this point. Some VCRs can even have weird hybrid filter networks and stuff which can go bad and there's nothing you can do for that.
Amazing that in the mid 1990s I paid good money to a tech school to learn how to fix VCRs and CRT TVs. Glad I didn't try to make that a career; it had basically evaporated within 10 years. As many VCRs as I've taken apart, I've never stripped down a video head assembly. Thanks!
I'm amazed that as recently as the '90s there were still people who'd rather pay someone to fix a TV or VCR than just replace it for what I imagine was close to the same price.
@@stevethepocketVCRs weren't *quite* "just buy another one if it breaks" cheap yet in the early 1990s, so people did actually pay to have them fixed. Disposable VCRs like the ones Funai made weren't until the late 1990s or so.
It’s astounding honestly that mechanical things of this complexity manage to be as reliable as they are, a testament to the engineers that designed them! In today’s age of so many things being all digital I’m kind of in awe of the mechanical complexity of these kinds of things.
I immediately recognized that as from a late 80s Toshiba VCR lol. It's always fun to see different the mechanisms were between manufacturers and eras. The core principles stayed the same, but the implementation varied wildly.
For a long time, the VCR was the finest-made object in anyone's home. They truly were a technological miracle - a miracle they worked not only at all, but very well!
Replacement heads were supplied as the drum with the two or more heads attached. So it’s just unsoldering the connections and removing the two screws to replace it.
The original videotape machines (1950s) were quad-head units (four heads) with vertical spinning heads that you needed to all align perfectly or the picture would be cut into four pieces! The modern VTR machine heads are all helical, scanning the tape horizontally at an angle, instead of vertically.
The "basket" is actually called the "tape elevator", and it lowers and raises the tape to be loaded. The loading ring loads the tape around the heads, and the spinning head assembly is called the scanner or upper drum assembly.
The Digi-Betacam has 17 heads on the upper drum! The upper drum used to cost $8000 dollars, and you had to go through a 400-page manual to re-align the entire transport, and adjust the tape playback and record interchange!
The hole in the base of the head assembly will just be for alignment, looks like the three screw holes are equidistant around the edge so you could install it 120 or 240 degrees out of alignment. The "not a motor" is maybe a variable reluctance sensor used for speed control.
That was super interesting. I've never seen inside a head drum. The complexity of this thing from the 80s or early 90s is impressive. No wonder VCRs were so expensive at the time. It's a shame technology like this get thrown away.
42:12 The stationary heads at the end of the tape path are both the erase head followed by the read/write head after. This erase head only erases the top and bottom edges of the tape, so the two linear tracks can be written immediately after. iirc, the top track is the linear audio track (mono or stereo suported in the same width), and the bottom track is the control track (sync). Keeping the two linear tracks on opposite ends of the medium reduces crosstalk, which would likely be an annoying buzz noise in the audio track.
This was a lot more interesting than I expected. I have a generally OK idea how a VCR works but some of the details I was unclear of were answered. I didn't think such a weak signal like off a video head could be picked up inductively like that either. I'm pretty impressed by that.
from what i understand back in the day they set the heads up on vibration free floors and stands to get the alinement right, still have a beta system and tapes for it, but mostly used these days to split out the stero audio from RF
The tape sitting on the drum is lubricated by the air that is present in the small grooves on the drum. Those grooves are in there to create a sort of air cushion. 👀👀
and the head tips are canted about 5 degrees in opposite directions to reduce crosstalk from the tape if the head should run across the wrong tape track
Seeing the head was fascinating because I've always had the same question! Seems like much of the complexity is simply due to the tape being housed in a cassette - I imagine it would be a lot simpler if the tape was supplied as a reel and the user threaded the tape manually (reel-to-reel style). Speaking of which, it would be great to see a kit offered which had a reel-to-reel design and came with a working head from a junked VCR, to allow full manual control and adjustments to see how the signal processing works in real-time while playing a tape...
Those must be the linotype, or teleprinter or steam locomotive technology of video recording, utterly complex and beautiful, but ultimately totally redundant!
This should amuse someone. Shortly after I moved into my first apartment, in the latter half of the 1980s, my parents bought themselves a new VCR, and they gifted me their old one. I gratefully accepted it, as VCRs still cost hundreds of dollars back then, at least for the stereo model I wanted, and my first job didn't pay all that well. I used it for several years, after which it started eating tapes. I've always had a knack for fixing things (or at least an interest in fixing things), and I was used to dealing with audio cassette decks, at least up to a point, so I decided to flip up the tape door on the VCR and see if I could figure out why the ol' girl had suddenly developed an appetite for VHS tape. Well, the first thing that greeted my eyes when I did that was the video head assembly, which, of course, was cocked at an angle. Since I knew nothing about how VCRs worked, as soon as I saw that, I jumped to the conclusion that some doodad in the assembly that moved the read/write head up and down had *obviously* broken, thus jamming the head at this weird angle, and since I knew of no way to identify that part, much less find a replacement and then figure out how to install it and readjust all the delicate pieces around it, I decided to just spring for a new VCR. (Pause now to laugh your *** off at my stupidity, but in my defense, even if the Internet as we know it today had coalesced by that time, all the world's knowledge was not yet on it, nor did I have access to a computer that could display formatted manuals and diagrams, so it's not as if VCR repair information was readily available to me.) Fast-forward to today (hopefully without the tape getting eaten😜), and I have now watched enough videos about how VCRs work - including this one - and how to repair them that I can almost laugh at my younger self puzzling over that old VCR. All I can say is it wasn't the last weird-looking mechanism I would ever encounter.
30:40 - That would be the *rotor* , in this case. Note that in ordinary electric motors, the rotor are wire-wound and the *stator* is the magnet which is stationary. In this case the two roles are reversed.
I graduated my second education as an electronic technician in 2000 (just a few years after my initial IT graduation.) During my time at the shop, between School sessions, i cleaned and calibrated a ton of VHS, Cd, DVD, tape drives ect. Good knowledge i have used to this day. Regarding the heads, there where a handfull of manufactures of Them. So sometimes a make and model from an other vender would fit. But not always. Thats why there was a compatibility note to a head. Fantastic tech from the 1970’s, presented in 2025. Almost 50 years after its invention. 😊
The motor for the head is Brushless synchronous type, the controller will "fire" usually 2 opposite coils at a time one of each polarity pulling and pushing the magnet then move to the next pair and then the next etc.
still remembering the sad day when Philips in Vienna sold off their head drum factory to Funai in mid 90ies (who basically closed it down and too the machinery to Asia for lower labor cost)
I have 3 Tascam DA88 (Hi8/8mm DAT) machines that I have been dreading opening to make one work out of the 3. Often people inquire about getting transfers made from recordings 30 years ago, but we no longer have working unit.
@@brentadams28 Ya, these have had hundreds of tapes through them, and they are generally tanks, but these have also been retired for the last 25 years and we had one working 10 or so years ago, but enough time has taken toll. I just don't know enough of the mechanics of them to feel good about fixing them. I'm gonna open the worst one (The tape-eater) to see what I can glean.
@ I was mainly referring to the notion of the possibility of transferring to a computer if it comes up that often. My old boss is 99.9% retired and gets bored.
The head goes down on the rotating shaft as low as possible without touching anything under it. Then you adjust the tracking with the tension rollers with a specific screwdriver designed for that purpose.
The head is a horseshoe (or similar) shape so it has two points of reference, then measures the difference between those points as the media moves past.
At one time i have repaired hundreds of them back in the 1980s thru 2000s I still have parts and manuals ! I still use one from time to time I still have one RCA's first models !
Drawing on experience from working on 1", U-matic, Betacam, and a few digital formats, I would say the heads on this machine are absolutely adjustable. To align them, you would ever so slightly loosen the fixing screw for the head assembly and insert special conical-tipped adjustment screws in the unpopulated holes to either side of the head. With the aid of an alignment tape and probing the correct test points, you would tighten/loosen the conical screws (which would apply lateral pressure against the head assembly) until you had the correct head alignment for both position and azimuth. Finally, you would re-tighten the fixing screw, remove the alignment screws, and you're (hopefully) done. I am surprised to see this same sort of setup on a VHS machine. I suspect head alignment became a one-time factory-set process in later models.
27:50 could that be a dew sensor to detect condensation on the video drum? I don't think it's anything to do with detecting the loading is complete as I would have thought the position of the mode switch would tell it that. 42:10 the head on the right is the combined audio and control track head, the one on the left erases just the audio track, this will be needed for the audio dub feature to wipe just the linear audio part of the tape leaving the video signal intact.
I think the non-motor thing is an electro brake. There were some VCRs that rewound super fast and to keep the tape from tearing when it was about to run out, a brake was necessary. (This is just a guess, I don't have insider knowledge)
That was a very interesting strip down, great to finally see what’s inside a video head. That rainbow effect I believe is caused by a clear anodising layer rather that the machining itself.
I don't think so. That is probably from the diffraction of very small machine grooves very close together. I see this all the time on precision machined parts. Unless they are polished, then that goes out the window. ^-^
I think I had one VCR that also had the ability to self-insert the tape by pushing "eject", but I don't remember which one. I believe it may have been a Philips that also had a "light pencil", which was a codebar reader embedded into a corner of the remote control to automatically set the program settings of a show you wanted to record. We never used that function because newspapers and TV guides here never implemented the technology (they more or less implemented it later, or rather a similar one with the numbers in plaintext, which I used with my last VCR set). As an interesting side note about that recording preset technology, Philips said in the user's guide that the codebar version had the ability to record especific shows (i.e. the VCR could detect which show was being broadcasted from a hidden code in the signal and record just that, even if there was an issue with the time tables), but from what I've seen of the plaintext version, it should just encode start time, end time and, if I remember it right, channel (meaning its reliability depends on the broadcaster's management abilities).
The funny thing is, they didn't. Tape cassettes had been around for a while (audio and data). Plus, video recording was a thing before it got to the home market. So your first non-professional VCR already had several years to decades of "how do you do this" behind them. The trickiest bit in my mind is wrapping the tape around the head. Everything else was already proven tech. What i mean by this, is that reel to reel tape machines had been around for quite a while, so tape speed control with a capstan and pinch roll was already well understood. As was how to keep tension on the system, rewind, fast forward, etc. Audio cassettes had already been figured out, so the packaging of the tapes was already basically figured out. Etc. Getting it engineered down to a reliable system, and then a cheap reliable system was the hard part! At least in my opinion. ^-^
I still say: any technology that works, is not junk by definition. It might not be the highest possible quality... low resolution... expensive to make... all of that is true, but I don't want to call it junk ever :)
the KOENIG cataloge of drive rework kits had a permanent place on my desk back in the days. they contained all felts for brake, backtension etc for a given chassis. And off course the notorious P7 arm of Panasonics G chassis, failing constantly after ANY sensor state mixup.
I had a JVC VCR 20 years ago,with an incondescent bulb in the middle and it definitely got mad for removing the cover. It had 8 separately adjustable channels, by manually turning a small cogwheel for each channel.
Time stamp 27:27 that is for grounding... most models have thet in the top of the headrum like a flap... this has it on the side so yes grounding for the heads
wow, amazing video! I really enjoyed it. What, contactless data transfer? Is that from the heads, do I understand that correctly? Such small signals transferred via induction? Wow! I have in mind some drums where there was a spring contact coming from the chassis touching the top of the spinning drum - but if I remember right it's just one pad, on the centre. Maybe it's for grounding as - as you say - such small signal can't be reliably transferred via sliding contacts. Thanks for this cool video!
The Hi-Fi audio is interleaved within the video RF envelope signal and is removed as a subcarrier of the video RF signal spectrum. The entire RF signal is then demodulated into the baseband video and audio information.
Back in the pre DVD days I worked for an audio / video tape duplication company in Sydney. We had a clean room for custom loading of VHS tape to match movie lengths. Quite a sight with hundreds and hundreds of JVC commercial VHS recorders. Masters were 1" tape and separate digital audio disc for audio. I had a Hitachi machine, built like a brick sh*thouse. Lol
I was curious to know if it was possible to emulate via software the entire image and sound processing stage from the analog signal collected from the magnetic heads. In this way, what was recorded on the tape could be digitized more faithfully.
The Video 2000 format uses slip rings with fingers, but for adjusting the head tracking using a microcontroller that does realtime adjustments to allow for some crazy trick play features. As well as get rid of that tracking control every other video machine had back then. Ah yes. And you can record on both sides of the tape, like a compact cassette. The problem with slip rings is that the faintest problem with a contact will materialize as snow in the picture.
Those motor bearings are probably preloaded bearings. Normal ball bearings have little clearance between balls and races, resulting in a slight amount of slop. For applications where no slop is permissible, such as hard disks, you can get preloaded bearings, where there is a slight press fit between balls and races, resulting in no slop at all.
Great! A **LONG** time ago😅, in my teens, I was very much into VCRs, so this video has been definitely yummy! Besides some other aspects already commented, I'd like to add some info, as briefly as possible... *I personally now at least ONE VCR (Philips VR6462) which had NO erase head at all, and some nerdy friends thought it was a short-lived trend! The advantage is having no static "falling off" after the end of a recording, although the quality w/o erase head suffered somewhat. Since the luma signal is FM-encoded, recording onto an "unerased" tape isn't that bad, but chroma (much lower frequencies) will get some interference -- you can notice that on the first few seconds of a new recording, since the erase head (when fitted!) is a rather long way before the video heads. *HiFi and flying erase heads need to be separate from the normal "head assemblies" (red and green on your head drum), but usually the extra heads for different recording speeds and/or trick play modes are integrated within the usual two assemblies, *very* close each other. Slower recording speeds "need" shorter heads in order to record the narrower tracks with minimal overlapping, but the trick play modes are a bit more complicated... In layman's terms, the two heads on a basic VCR are of two kinds -- let's call them A- and B-type. Thus, every field is recorded by one head type, resulting on an ABABABAB... sequence on the tape. Normal playback can be synced so each head runs over its corresponding track (A-heads do fine "A tracks", but cannot read "B tracks" and vice versa). But this alternation is lost when you stop the tape with the drum spinning in order to get a still picture (or at any abnormal play speed). Suppose the tape stops when the head path is over an A-track. When A-head is on, it will read OK; but the B-head won't, so it will generate noise bands and jitter. A 3-head VCR gets perfect still picture because it adds an extra A-head *just* beside the B-head on the B assembly -- let's call it A'. So, when the B assembly hovers the tape, the B-head is switched out for the A'-head, which *can* read the A-track, giving a noiseless picture on both passes. Furthermore, 4-head VCRs have an AB' head "combo" in one assembly, and A'B on the other, so no matter the assembly currently over the track, there's always an appropriate head to read it. For cost reasons, the usual thing is to use, for instance, SP-style heads for AB, and EP heads for A'B' (located just the other way round)... On trick modes, the "alternate" heads, even if they are not of the optimum size, will perform acceptably (and much better than the other "non-alternative" head!) In practice, this is of course WAY more complex, but I hope you get the gist...
awesome video! i now know how very little i know about vcr's! lol i assumed if i took it apart i could figure it out, but nope, not possible! how that head gets the info off the tape and turns it into audio/video i have no idea. thank you for pointing out how very stupid i really am!
I enjoyed your teardown, I never really understood the VCR mechanisms but have been fascinated by them. I can't imagine the engineering that created this. It's like the electromechanical version of analog television! So much complexity and it just works. BTW, your patron list scrolls by too fast. Would you find a way to give recognition that is readable?
Probnot's Tech is a good channel to watch to see how VCRs go together, he's got loads of videos taking them apart & fixing them up, as well as bringing some back to life that look like they have no business working again, even has his own DIY in-house analogue cable TV network on the go which is neat... :P
![Adrian's Digital Basement ][](http://yt3.ggpht.com/ytc/AIdro_k7CrQRe71qN6c0Ua7A1P_I8KkxjqLa70u0zYeCvdvnKw=s48-c-k-c0x00ffffff-no-rj)
Several patrons pointed out this great article on Wikipedia showing a photo of a disassembled six head VHS head: en.wikipedia.org/wiki/Helical_scan
My first VCR was a 6 head that i bought in 1987? (i think). Their big selling point was the heads were "glass encapsulated." All i know is i gifted that VCR to my parents at one point, and it was still working over 20 years later. Of course, they were not heavy VCR users, but still.
42:12 - The head on the left is the *audio* erase head. This was used if one wanted to 'dub' audio onto the tape; it would erase the audio track without erasing the video. The full-width erase head is located 'upstream' from the video heads (to the left of the mechanism).
The only VCR that I've seen with this 'dub' feature was my Quasar model from 1979.
The "some sort of hall effect sensor" is actually a grounding brush to discharge the static generated by the tape moving over the spinning upper drum assembly.
Ooh spark gap
I did TV and VCR repairs in the mid-ninties in the UK. You had to do some alignment adjustments, of course, but the heads, in fact the head drum, were indeed replaceable. You could get new head rums or rebuilt drums from specialist suppliers, such as CPC in the UK, which were much more economic and in some cases better than the originals! Not cheap, typically £30-60 with original Sony heads being significantly more expensive. The alignment of the heads on the drum is critical and done under specilist microscpes, so you get a complete upper drum, not the heads themselves. They were wired in pairs, either in series or parallel so a fully stuffed head drum had to have three rotating transformer coils, one for the basic two heads, one for the extra pair on a four head machine and one for the Hifi track if fitted.
The tape baskets were indeed srevice replaceable. When people tried to get a tape out by force, the basket often got bent such that replacement was the only fix. Quite expensive but generally a pretty easy fix. You could get belt and service kits for practically all deck families. Some decks were complex and a nightmare for repairs, such as the Panasonic J deck, one of the very few I had to get a proper service manual for as it had just one motor to do everything and loads of gears which had to be carefully synchronised - they had holes and the service manual was nigh on essential to getting the gear realignment right, after, say, replacing the tape basket. Lots of VCR makers bought decks in and put them in their own VCRs. One common OEM deck make used by many low cost VCR makers was Goldstar who at the time was almost an unknown in the UK. In the mid-ninties, about the time I got out of the repairs game, they changed their name to "Lucky Goldstar" or LG...
Years ago I took apart an older VCR, then months later a much newer VCR. The difference was night and day, with the newer one built right down to a cost. Thin stamped sheet stock, lots of plastic, motors doing multiple tasks instead of there being multiple motors.
The older version was exquisitely built :D Cast aluminium body with lots of gears and belts, several motors, lots going on. It was incredible seeing it in operation and every part of the mechanism working as you inserted a cassette and watched it spool up
I spent around 20 years working on VCRs and it was notable how the mechanisms became simpler and ultimately flimsier with cost reduction. Good times while it lasted, well, mostly!
The VCR is a fascinating device. A lot of mechanical parts designed to maximize the amount of tape path for the record/playback head. The video quality is poor compared to today's demands, but it's amazing to know how much data was actually being stored already on that VHS
Adrian would have had a lot of fun digging through my old Zenith Beta. It was one of the early VCRs, and very large
@@CyranoJones509 indeed, I recall Gary Kildall talking at length in the late 80s how amazing it was that video was the equivalent to many gigabytes. He was especially focused on laserdisc, since it had random-access, but IIRC also discussed how VHS and Beta could be used for even larger offline backups.
@ I hadn't heard that before, but I do recall a board that allowed the Tandy 1000 (?) to use a VCR for a backup storage device
For my own purposes, I discovered that a HiFi VCR served as an excellent music medium since each playback was synchronized to the timebase stored on the tape
@@CyranoJones509 it was while going through the Computer Chronicles backlog, alas that means I can’t point to one specific episode as there’s so many 😅
My dad had his VCR hooked up to his hifi (my older brother’s biker friend set it up) for playback but he only ever dubbed onto type-2 cassette, haha. It was for his car so it tracks, but, still lol
@@CyranoJones509Indeed! It was one of the most advanced mainstream electromechanical devices to grace our homes. Now all the wizardry is hidden in silicon, pushed beyond intuitive understanding that mere dismantling once revealed.
The capstan has a coil that produces a tone that is used to control the speed though a phased locked loop circuit. In a VCR everything has to be controlled just right
When I was like 7 or something I "fed" Lucky Charm marshmallows to my dad's VCR. It wasn't long until he used it and it didn't take very long for things to go wrong. Apparently it spent a couple weeks at a repair shop and the guy had to completely disassemble and clean all the components. It's a very nice model from the 70's and still works. Whenever the video/audio starts getting "trippy" from old worn out Christmas movies I joke about it having to do with the marshmallows.
I totally expected to see a bunch of fingers connecting to a multi layer centre post inside the video drum, so I was a bit surprised to see the induction setup. The reason is because I tore apart a very early model VCR some 25 years ago and I swear that's what I saw, but maybe I'm misremembering it. It was a JVC HR3300 rebadged as a Rank Arena, and it weighed a freakin ton. Obviously it was broken and my attempts to repair it failed, probably because I had no idea what I was doing back then, so I tore it all apart instead. Pretty sure I still have some of the one million machine screws in my random screws bin
Very old video tape recorders which used helical scan used that method, but by the time beta and vhs came out, they had switched to wireless rotary transformers. (Including the jvc 3300u.)
Philips VCC2000 recorders I worked on (ages ago) also had these transformers in their head drums. We were able to pick up scrapped recorders that had manufacturing defects and then combine the working parts from two or three of those into a working recorder. Then sold those for a friendly price to friends of ours 😊
Slip rings can be used, but are noisy, which is NOT good for signal integrity. Induction is a much better system, as there is no mechanical joint, just electromagnetic coupling.
Some of Sony's Betacam SP machines used slip rings for ancillary functions, like piezo dynamic tracking and on-wheel head amplifier power.
Even an old video 2000 vcr maybe from 1980 or maybe older. Had induction to transfer the video signal.
That whole thing was made of steel parts. Even the parts that stuck inside the tape to roll. The spools.
Looked like it could make crater if you dropped it.
Just imaging the signal levels involved from the flying head , and the eventual video, a work of technical art.
@34:34, That third unused coil is for Hi-Fi audio or a 'Flying Erase Head'... VHS HiFi audio is written inbetween the video tracks on a dedicated set of heads at an alternate azimuth to not interfere with the video tracks. A flying erase head is used in VCRs which allow frame accurate insertion recording. A fully featured VCR will have 4 coils for commutation of all the different head types. However, 4 head VCRs use only 2 main coils like the one you are showing. (Count the number of desoldered contacts you needed to do to lift off the top of the video head, is was 8, or 4 per side. If you were desoldering for a 2 head VCR, you would have desoldered 4 contacts, 2 on each side. However, when you go further into your head disassembly, you see only 2 coil contacts are soldered on each head meaning this is a 2 head VCR even though it the head drive was capable of handling the 4 contacts for a 4 head VCR) For the 4 head VCRs, the 2 heads you see on each side of the spinning video actually has 2 heads right up against each other with one head at a slightly alternate height so that when you pause the video tape, the current video frame field is displayed on the main head, but since the tape is no longer in motion, the alternate height head can pick up the same video track since it looses alignment along a motionless tape as the tape was recorded in motion. For 2 head VCRs, you only need a single coil with both heads tied in parallel. Remember, only 1 head is in contact with the tape at 1 time while the other head is open in mid air. Do not confuse HiFi VCR heads where you actually see 4 heads on the video head drum. Those VCRs usually have the 4 video heads for perfect freeze fame plus another 2 heads at a 90 degree offset for the HiFi audio. These VCRs actually have 6 heads.
This is the first time in my life that I've actually seen an explanation for what "4-head" really means on a VCR. Thanks for that. Makes perfect sense.
@@nickwallette6201 I did make 1 mistake in the above description, please excuse me as the last time I worked on a VCR was decades ago. 2 coils were used, 1 for each side of the playback heads. The reason for this is there is a little overlap on the video tape when playing back from choosing 1 head to the next. This offers a brief moment in time where the VRC electronics can perform a rapid switchover from 1 head on one side at the end of a video frame to the next head beginning actually right at the bottom of the picture, ready to begin the next frame. Without the rapid selection switch with 2 separate coils side of the video head, you will get a messy joint as 1 head begins to pickup the next part of the next frame. Especially as the video tape itself may begin to stretch over it's life or may have come from a slightly differently aligned VCR. If you had an old analog CRT monitor with an adjusted v-size where you could see the overscan of the video playback, you might get a glimps at the bottom of the picture a horizontal miss-alignment during this read head swap as your CRT may not adjust fast enough horizontally to capture the slight timing alignment during that swap. This bend does not exist on live cameras or professional broadcasts which have time-base-corrected analog video tape players or digital tape players.
You've voided the warranty!
If you don't have a digital microscope I highly suggest getting one for these kind of explorations as, even the cheap one's, can really show great detail of these teeny tiny components.
Aside from a VCR mechanism, my other favorite one is the slot loading DVD drive in the GameCube compatible Wii systems as it could take both the standard 12cm optical disc but it could also accept the 8cm mini-DVDs that the GameCube used and it didn't matter where you inserted the mini DVD as it could automatically align it to the center. It was so cool the way the "arms" would sort of hug the disc to center it. So many parts working in unison for it to be able to accept GameCube disc. It would have been so much cheaper to use a standard tray or what the GameCube used.
I forgot to mention the Dehedral adjustment needed to center an upper head drum when replacing video heads. That adjustment was done to center the upper head drum on the lower head drum assembly. Also that edge you saw cut into the lower head drum assembly is a 'rabbit' that is a guide to control how the tape passes by the heads. After so many head hours, the lower head drum had to be replaced as the aluminum that the tape would touch passing by in playback or record, would get so the aluminum so smooth that the tape would stick to the drum (called slip-stiction) and lower head drums had to be completely replaced and are VERY expensive. The OEM would ship a fully aligned drum assembly for replacement and send back the old one for refurbishment. Ahh, the joy of tape-based video playback.
Thanks again,
Gerry
The lower video drum motor is called a pancake motor. It is a brushless three-phase motor with a rotary encoder built into the assembly.
Nice Video, I was also curious how the inside worked ,now I know :D
I can't tell you how many VCR's I took apart as a kid - they used to be very common trash items. I'd probably find one or three every year. Sometimes they would even still work. Those days are long gone, so thank you for showing this for all those in the future who won't get the chance!
I've always wondered how the connections were made on those spinning heads too. Now I know. Thanks!
I enjoyed Tim Hunkin's 'The Secret Life of Machines' videorecorder episode from back in the 90s I think. It's available on RUclips.
I thought I was the only person who sees the beauty of things like this... Glad to find out I'm not alone. Great video Adrian, thanks!
I have done a lot of home machining, and that drum assembly, is truly a work of art. This was an enjoyable, educational video.
I have a couple of the top of the line Thompson VCRs, that date back to the 80s, that I would like to make operational again. One of the units, just has a deteriorated belt, and I haven't taken the time to source a replacement. After watching this, I am motivated to get after it again. .
I have a VCR somewhere I tried to get in to 15 years ago after it had been had degraded video playback since like 2000 or so which had stopped working by like 2008. I think it really is just dry belts and tires. Honestly, it's probably easier to repair this sort of thing now, as far as like, finding belt kits and things for a specific model of VCR. If I was generally more motivated and less worried about breaking it more, I'd try to get in to it again. It was a nice VCR as far as I recall, though I know it has a lot of hours of recording TV and watching movies. Who knows, maybe it's full of blown caps at this point. Some VCRs can even have weird hybrid filter networks and stuff which can go bad and there's nothing you can do for that.
The part at 27:50 is the dew sensor that detects possible moisture on the tapehead and prevents loading of the tape.
Your channel is the best, long videos full of retro sweetness!!!
Amazing that in the mid 1990s I paid good money to a tech school to learn how to fix VCRs and CRT TVs. Glad I didn't try to make that a career; it had basically evaporated within 10 years. As many VCRs as I've taken apart, I've never stripped down a video head assembly. Thanks!
I'm amazed that as recently as the '90s there were still people who'd rather pay someone to fix a TV or VCR than just replace it for what I imagine was close to the same price.
@@stevethepocketVCRs weren't *quite* "just buy another one if it breaks" cheap yet in the early 1990s, so people did actually pay to have them fixed. Disposable VCRs like the ones Funai made weren't until the late 1990s or so.
It’s astounding honestly that mechanical things of this complexity manage to be as reliable as they are, a testament to the engineers that designed them! In today’s age of so many things being all digital I’m kind of in awe of the mechanical complexity of these kinds of things.
I immediately recognized that as from a late 80s Toshiba VCR lol. It's always fun to see different the mechanisms were between manufacturers and eras. The core principles stayed the same, but the implementation varied wildly.
For a long time, the VCR was the finest-made object in anyone's home. They truly were a technological miracle - a miracle they worked not only at all, but very well!
Replacement heads were supplied as the drum with the two or more heads attached. So it’s just unsoldering the connections and removing the two screws to replace it.
Incredible engineering really.
The original videotape machines (1950s) were quad-head units (four heads) with vertical spinning heads that you needed to all align perfectly or the picture would be cut into four pieces!
The modern VTR machine heads are all helical, scanning the tape horizontally at an angle, instead of vertically.
43:23 - I believe the center-lamp and sensors are used for detecting if a tape is present.
The "basket" is actually called the "tape elevator", and it lowers and raises the tape to be loaded. The loading ring loads the tape around the heads, and the spinning head assembly is called the scanner or upper drum assembly.
this is the first time in a long time that I screamed at my monitor over grub screws lmao
Adrian’s Analog Basement
Oh, you should search out some Sony Betacam and Digital Betacam VTR machines, they are on a different level.
The Digi-Betacam has 17 heads on the upper drum! The upper drum used to cost $8000 dollars, and you had to go through a 400-page manual to re-align the entire transport, and adjust the tape playback and record interchange!
The hole in the base of the head assembly will just be for alignment, looks like the three screw holes are equidistant around the edge so you could install it 120 or 240 degrees out of alignment.
The "not a motor" is maybe a variable reluctance sensor used for speed control.
Thanks for this Adrian! I have always wanted to see what a vcr head looked like.
That was super interesting. I've never seen inside a head drum. The complexity of this thing from the 80s or early 90s is impressive. No wonder VCRs were so expensive at the time. It's a shame technology like this get thrown away.
The head "turny" mechanism is called the lower drum rotary transformer.
47:30 - I've found that Ivory Soap (no oily additives!) is great at 'rejuvenating' rubber parts.
42:12 The stationary heads at the end of the tape path are both the erase head followed by the read/write head after. This erase head only erases the top and bottom edges of the tape, so the two linear tracks can be written immediately after. iirc, the top track is the linear audio track (mono or stereo suported in the same width), and the bottom track is the control track (sync). Keeping the two linear tracks on opposite ends of the medium reduces crosstalk, which would likely be an annoying buzz noise in the audio track.
45:20 might be a magnetic brake.
This was a lot more interesting than I expected. I have a generally OK idea how a VCR works but some of the details I was unclear of were answered. I didn't think such a weak signal like off a video head could be picked up inductively like that either. I'm pretty impressed by that.
from what i understand back in the day they set the heads up on vibration free floors and stands to get the alinement right, still have a beta system and tapes for it, but mostly used these days to split out the stero audio from RF
The tape sitting on the drum is lubricated by the air that is present in the small grooves on the drum. Those grooves are in there to create a sort of air cushion. 👀👀
and the head tips are canted about 5 degrees in opposite directions to reduce crosstalk from the tape if the head should run across the wrong tape track
The mechanical complexity is mind-boggling!
Seeing the head was fascinating because I've always had the same question! Seems like much of the complexity is simply due to the tape being housed in a cassette - I imagine it would be a lot simpler if the tape was supplied as a reel and the user threaded the tape manually (reel-to-reel style). Speaking of which, it would be great to see a kit offered which had a reel-to-reel design and came with a working head from a junked VCR, to allow full manual control and adjustments to see how the signal processing works in real-time while playing a tape...
14:35 - Where's the Erase Head? (should be to the left of the head-drum).
Those must be the linotype, or teleprinter or steam locomotive technology of video recording, utterly complex and beautiful, but ultimately totally redundant!
High tech for its time, and still impressive.
NSK bearings, they were great in skateboards.
Yes NSK speed bearings
You can swap the heads between the same model of VTR. I've changed a lot of video heads and upper and lower drums during my career!
This should amuse someone. Shortly after I moved into my first apartment, in the latter half of the 1980s, my parents bought themselves a new VCR, and they gifted me their old one. I gratefully accepted it, as VCRs still cost hundreds of dollars back then, at least for the stereo model I wanted, and my first job didn't pay all that well. I used it for several years, after which it started eating tapes. I've always had a knack for fixing things (or at least an interest in fixing things), and I was used to dealing with audio cassette decks, at least up to a point, so I decided to flip up the tape door on the VCR and see if I could figure out why the ol' girl had suddenly developed an appetite for VHS tape. Well, the first thing that greeted my eyes when I did that was the video head assembly, which, of course, was cocked at an angle. Since I knew nothing about how VCRs worked, as soon as I saw that, I jumped to the conclusion that some doodad in the assembly that moved the read/write head up and down had *obviously* broken, thus jamming the head at this weird angle, and since I knew of no way to identify that part, much less find a replacement and then figure out how to install it and readjust all the delicate pieces around it, I decided to just spring for a new VCR. (Pause now to laugh your *** off at my stupidity, but in my defense, even if the Internet as we know it today had coalesced by that time, all the world's knowledge was not yet on it, nor did I have access to a computer that could display formatted manuals and diagrams, so it's not as if VCR repair information was readily available to me.) Fast-forward to today (hopefully without the tape getting eaten😜), and I have now watched enough videos about how VCRs work - including this one - and how to repair them that I can almost laugh at my younger self puzzling over that old VCR. All I can say is it wasn't the last weird-looking mechanism I would ever encounter.
This type of video is definitely for me! ❤
30:40 - That would be the *rotor* , in this case. Note that in ordinary electric motors, the rotor are wire-wound and the *stator* is the magnet which is stationary. In this case the two roles are reversed.
I graduated my second education as an electronic technician in 2000 (just a few years after my initial IT graduation.)
During my time at the shop, between School sessions, i cleaned and calibrated a ton of VHS, Cd, DVD, tape drives ect. Good knowledge i have used to this day.
Regarding the heads, there where a handfull of manufactures of Them. So sometimes a make and model from an other vender would fit. But not always. Thats why there was a compatibility note to a head.
Fantastic tech from the 1970’s, presented in 2025. Almost 50 years after its invention. 😊
a real voyage of discovery Adrian
The takeup, supply hubs, and all the spinning gears for fast forward and reverse are on the reel table.
Well this answered my curiosity as well! Thanks 😊
The motor for the head is Brushless synchronous type, the controller will "fire" usually 2 opposite coils at a time one of each polarity pulling and pushing the magnet then move to the next pair and then the next etc.
still remembering the sad day when Philips in Vienna sold off their head drum factory to Funai in mid 90ies (who basically closed it down and too the machinery to Asia for lower labor cost)
I have 3 Tascam DA88 (Hi8/8mm DAT) machines that I have been dreading opening to make one work out of the 3. Often people inquire about getting transfers made from recordings 30 years ago, but we no longer have working unit.
My old bosses DA88s are still in working order as far as I know. I’ve done many sessions on those machines.
@@brentadams28 Ya, these have had hundreds of tapes through them, and they are generally tanks, but these have also been retired for the last 25 years and we had one working 10 or so years ago, but enough time has taken toll. I just don't know enough of the mechanics of them to feel good about fixing them. I'm gonna open the worst one (The tape-eater) to see what I can glean.
@ I was mainly referring to the notion of the possibility of transferring to a computer if it comes up that often. My old boss is 99.9% retired and gets bored.
The head goes down on the rotating shaft as low as possible without touching anything under it. Then you adjust the tracking with the tension rollers with a specific screwdriver designed for that purpose.
The head is a horseshoe (or similar) shape so it has two points of reference, then measures the difference between those points as the media moves past.
Wikipedia has an article on rotary transformers which shows a shot what's under a 6 head VCR, very neat.
I just saw that! Super cool and something I had somehow never seen.
At one time i have repaired hundreds of them back in the 1980s thru 2000s I still have parts and manuals ! I still use one from time to time I still have one RCA's first models !
Drawing on experience from working on 1", U-matic, Betacam, and a few digital formats, I would say the heads on this machine are absolutely adjustable. To align them, you would ever so slightly loosen the fixing screw for the head assembly and insert special conical-tipped adjustment screws in the unpopulated holes to either side of the head. With the aid of an alignment tape and probing the correct test points, you would tighten/loosen the conical screws (which would apply lateral pressure against the head assembly) until you had the correct head alignment for both position and azimuth. Finally, you would re-tighten the fixing screw, remove the alignment screws, and you're (hopefully) done.
I am surprised to see this same sort of setup on a VHS machine. I suspect head alignment became a one-time factory-set process in later models.
Thanks for all the awesome videos!
27:50 could that be a dew sensor to detect condensation on the video drum? I don't think it's anything to do with detecting the loading is complete as I would have thought the position of the mode switch would tell it that. 42:10 the head on the right is the combined audio and control track head, the one on the left erases just the audio track, this will be needed for the audio dub feature to wipe just the linear audio part of the tape leaving the video signal intact.
I think the non-motor thing is an electro brake. There were some VCRs that rewound super fast and to keep the tape from tearing when it was about to run out, a brake was necessary. (This is just a guess, I don't have insider knowledge)
That was a very interesting strip down, great to finally see what’s inside a video head. That rainbow effect I believe is caused by a clear anodising layer rather that the machining itself.
I don't think so. That is probably from the diffraction of very small machine grooves very close together. I see this all the time on precision machined parts. Unless they are polished, then that goes out the window. ^-^
I think I had one VCR that also had the ability to self-insert the tape by pushing "eject", but I don't remember which one. I believe it may have been a Philips that also had a "light pencil", which was a codebar reader embedded into a corner of the remote control to automatically set the program settings of a show you wanted to record. We never used that function because newspapers and TV guides here never implemented the technology (they more or less implemented it later, or rather a similar one with the numbers in plaintext, which I used with my last VCR set). As an interesting side note about that recording preset technology, Philips said in the user's guide that the codebar version had the ability to record especific shows (i.e. the VCR could detect which show was being broadcasted from a hidden code in the signal and record just that, even if there was an issue with the time tables), but from what I've seen of the plaintext version, it should just encode start time, end time and, if I remember it right, channel (meaning its reliability depends on the broadcaster's management abilities).
Imagine sitting down with a blank sheet of paper and starting to design this!
The funny thing is, they didn't. Tape cassettes had been around for a while (audio and data). Plus, video recording was a thing before it got to the home market. So your first non-professional VCR already had several years to decades of "how do you do this" behind them. The trickiest bit in my mind is wrapping the tape around the head. Everything else was already proven tech.
What i mean by this, is that reel to reel tape machines had been around for quite a while, so tape speed control with a capstan and pinch roll was already well understood. As was how to keep tension on the system, rewind, fast forward, etc. Audio cassettes had already been figured out, so the packaging of the tapes was already basically figured out. Etc.
Getting it engineered down to a reliable system, and then a cheap reliable system was the hard part! At least in my opinion. ^-^
This was cool!
Now I know why vhs players were so expensive.
I still say: any technology that works, is not junk by definition. It might not be the highest possible quality... low resolution... expensive to make... all of that is true, but I don't want to call it junk ever :)
@@atkelar the VCR is still a modern marvel in my mind.
@@JonnyFlash80 When I was born consumer VCRs weren't a thing yet (B&W Telly with one tuning knob, was all we had🥲).. So I tend to agree..
the KOENIG cataloge of drive rework kits had a permanent place on my desk back in the days. they contained all felts for brake, backtension etc for a given chassis. And off course the notorious P7 arm of Panasonics G chassis, failing constantly after ANY sensor state mixup.
oh wow these heads were always black magic to me, that was super interesting!
I have always wondered what the actual heads looked like so now I know. Next thing will be the decoding of the video track information!
7:58 Sony did use VHS M-style loading mechanism on some Betacam decks, but that's rather the exception proving the rule.
"How did this get twisted like this? I don't get it!" car owners examining their seatbelts be like
I had a JVC VCR 20 years ago,with an incondescent bulb in the middle and it definitely got mad for removing the cover. It had 8 separately adjustable channels, by manually turning a small cogwheel for each channel.
Time stamp 27:27 that is for grounding... most models have thet in the top of the headrum like a flap... this has it on the side so yes grounding for the heads
wow, amazing video! I really enjoyed it. What, contactless data transfer? Is that from the heads, do I understand that correctly? Such small signals transferred via induction? Wow! I have in mind some drums where there was a spring contact coming from the chassis touching the top of the spinning drum - but if I remember right it's just one pad, on the centre. Maybe it's for grounding as - as you say - such small signal can't be reliably transferred via sliding contacts.
Thanks for this cool video!
Adrians not so digital basement.
The Hi-Fi audio is interleaved within the video RF envelope signal and is removed as a subcarrier of the video RF signal spectrum.
The entire RF signal is then demodulated into the baseband video and audio information.
I believe the connection from the heads to the playback and record amplifier is called a rotary transformer, not a slip ring.
Love this Chanel ❤
I think this would go great a lot side Technology Connection's video on how a VHS mechanism works.
Back in the pre DVD days I worked for an audio / video tape duplication company in Sydney. We had a clean room for custom loading of VHS tape to match movie lengths. Quite a sight with hundreds and hundreds of JVC commercial VHS recorders. Masters were 1" tape and separate digital audio disc for audio. I had a Hitachi machine, built like a brick sh*thouse. Lol
I was curious to know if it was possible to emulate via software the entire image and sound processing stage from the analog signal collected from the magnetic heads. In this way, what was recorded on the tape could be digitized more faithfully.
The Video 2000 format uses slip rings with fingers, but for adjusting the head tracking using a microcontroller that does realtime adjustments to allow for some crazy trick play features. As well as get rid of that tracking control every other video machine had back then.
Ah yes. And you can record on both sides of the tape, like a compact cassette.
The problem with slip rings is that the faintest problem with a contact will materialize as snow in the picture.
I've tried changing out the little head boards before. It was impossible to align it correctly after
Those motor bearings are probably preloaded bearings. Normal ball bearings have little clearance between balls and races, resulting in a slight amount of slop. For applications where no slop is permissible, such as hard disks, you can get preloaded bearings, where there is a slight press fit between balls and races, resulting in no slop at all.
I find it kinda insane the tech used in VCRs and yet how we now consider them dinosaurs :P
Great! A **LONG** time ago😅, in my teens, I was very much into VCRs, so this video has been definitely yummy!
Besides some other aspects already commented, I'd like to add some info, as briefly as possible...
*I personally now at least ONE VCR (Philips VR6462) which had NO erase head at all, and some nerdy friends thought it was a short-lived trend! The advantage is having no static "falling off" after the end of a recording, although the quality w/o erase head suffered somewhat. Since the luma signal is FM-encoded, recording onto an "unerased" tape isn't that bad, but chroma (much lower frequencies) will get some interference -- you can notice that on the first few seconds of a new recording, since the erase head (when fitted!) is a rather long way before the video heads.
*HiFi and flying erase heads need to be separate from the normal "head assemblies" (red and green on your head drum), but usually the extra heads for different recording speeds and/or trick play modes are integrated within the usual two assemblies, *very* close each other. Slower recording speeds "need" shorter heads in order to record the narrower tracks with minimal overlapping, but the trick play modes are a bit more complicated... In layman's terms, the two heads on a basic VCR are of two kinds -- let's call them A- and B-type. Thus, every field is recorded by one head type, resulting on an ABABABAB... sequence on the tape. Normal playback can be synced so each head runs over its corresponding track (A-heads do fine "A tracks", but cannot read "B tracks" and vice versa). But this alternation is lost when you stop the tape with the drum spinning in order to get a still picture (or at any abnormal play speed). Suppose the tape stops when the head path is over an A-track. When A-head is on, it will read OK; but the B-head won't, so it will generate noise bands and jitter. A 3-head VCR gets perfect still picture because it adds an extra A-head *just* beside the B-head on the B assembly -- let's call it A'. So, when the B assembly hovers the tape, the B-head is switched out for the A'-head, which *can* read the A-track, giving a noiseless picture on both passes. Furthermore, 4-head VCRs have an AB' head "combo" in one assembly, and A'B on the other, so no matter the assembly currently over the track, there's always an appropriate head to read it. For cost reasons, the usual thing is to use, for instance, SP-style heads for AB, and EP heads for A'B' (located just the other way round)... On trick modes, the "alternate" heads, even if they are not of the optimum size, will perform acceptably (and much better than the other "non-alternative" head!)
In practice, this is of course WAY more complex, but I hope you get the gist...
awesome video! i now know how very little i know about vcr's! lol i assumed if i took it apart i could figure it out, but nope, not possible! how that head gets the info off the tape and turns it into audio/video i have no idea. thank you for pointing out how very stupid i really am!
I enjoyed your teardown, I never really understood the VCR mechanisms but have been fascinated by them. I can't imagine the engineering that created this. It's like the electromechanical version of analog television! So much complexity and it just works.
BTW, your patron list scrolls by too fast. Would you find a way to give recognition that is readable?
Probnot's Tech is a good channel to watch to see how VCRs go together, he's got loads of videos taking them apart & fixing them up, as well as bringing some back to life that look like they have no business working again, even has his own DIY in-house analogue cable TV network on the go which is neat... :P
Adrian, you should add a USB camera to your microscope for those (& similar future) close-ups. This was very interesting --> thumbs-up!
Didnt know the video heads actually scraped along the tape! Always assumed it was slightly off it. No wonder theyd get dirty and damaged easily.