I just realized why I bet they used a shrunken pic on a larger crt. I bet it was to make use of the flattest part of it so there was no distortion at the corners since distance in the ultrasound image was critical.
and black and white screen, so there is a dot-screen mask? and going to an optical film camera anyway, and that most have it with lens optics too; the full screen was so large all ready, so idealy a smaller CRT might be better? but may not have exsisted, and if did, there sosable not ruged and sell biuld for left 24/7 everyday for years, the cheaply available sercurity monoyor where, and being ready market sellers, and good enuth is good enuth they just when the readyly available cheaper option than something made in house
Yeah they're sort of approximating a scope tube with the lower deflection angles for higher precision, but with a shallower tube, a real scope tube that size would be much longer and might not fit where ever they put it (also, cheaper)
That and the film frame was square, so yeah you wanted to use the centermost part of the screen for the least distortion. Ultrasound machine at the time weren't fully digital and couldn't crop the image to the center of the frame, so the simplest thing was to modify the monitor.
GBC is "Gian Bruto Castelfranchi", it was an italian company and they had a division overseas. Usually they sold rebranded TVs and monitors, their main business was sold spare parts btw.
Yes, I remember this company logo here in Italy when I was young. In a GBC shop that sold electronics my brother bought a ROM cartridge for our TI99/4A :)
In regards to your closing comments, Adrian, I'm pretty sure we're all here to see the repairs, so anything you think anybody might find interesting, definitely post it to one of your channels!
@@adriansdigitalbasement FDA Rule 21 Subchapter J (marked here as a DHEW [now DHHS] rule; the FDA was/is under DHEW/DHHS) has to do with regulating radiological emissions from electronic equipment.
@@adriansdigitalbasement 21 CFR Subchapter J focuses on Radiological Health and includes regulations related to electronic products that emit radiation. Whereas FCC covers RF interference, my guess is DHHS and DHEW covers human safety
@@adriansdigitalbasement I imagine this monitor was sold as a part of or add-on for the scanner. So being sold for use in a medical environment, it would be considered medical equipment.
My assumption is that Toshiba used GBC as a monitor supplier for their medical devices. They resprayed already existing monitors to beige to match the rest of Toshiba's equipment.
high end Japanese equipment of the era was bodgy but not THIS bodgy. I think Toshiba just marked it up 10x because "medical device" and replacement part was out of budget for the end user, so they went and found some handymen who made a good enough replica of the original monitor.
Yep. Medical equipment is filled with rebadged electronics. Famously the CRT Olympus OEV monitors are rebadged Sony PVMs. Its a lot easier for the Hospital, Supplier, Technicians exc if a device with multiple parts is sold, serviced, and warrantied as 1 complete 'Unit' rather then the customer having to deal with each individual company if a part breaks. @denisdrozdoff2926 The Bodgy nature of this example likely comes from a 3rd party medical supplier's repair services. My old Boss used to fix medical equipment thats support was discontinued from the manufacturer. Stuff like this can be in the field for 20+ years and prior to the internet trying to source an exact part of a discontinued machine like could be difficult and more costly then adapting another tube to the chassis.
Adrian's Analog Basement - Great video, I really enjoy these monitor shenanigans, not many retro computing enthusiasts actually get into that topic. :)
7:04 Those are SO-239 connectors, which mate with [EDIT]PL-259 plugs. Also called "UHF" connectors, despite being totally unsuitable for use much above 100MHz.
Had someone told me I would watch with rapt attention a video about 45 year old analog tech I would have laughed. You sir are a master teacher and storyteller. Cheers from Canada!
@1:03:15, the 60hz bend you see might not be EMF, but, an actual magnetic field coming from the monitor's mains transformer interfering with the deflection on the CRT. Otherwise, it may be a dying decoupling cap for the yoke's deflection driver IC's power supply.
To avoid the effects of the magnetic field generated by the monitor's main power transformer, the transformer is positioned at approximately 45 degree angle.
Yeah, but it was virtually impossible to completely eliminate the Hum Bar. The other trick was to put a band of copper tape around the outside of the transformer to short out any external field.
I love seeing hand drawn circuit boards. Good memories from childhood when we’d get copper coated boards from Radio Shack and resist pens / rub down film to make them for projects.
@ I don’t remember. It was just some dark brown liquid from what I can remember. In college for an art class, I did some photo etching and that was completely different. Very toxic stuff. The professor was surprised I could just buy it from an electronics shop. It probably was, but at 19 were all invincible.
such an exciting video! I was so thankful at 36 minutes when you decided to open those back screws like I had been begging for you to do for 5 minutes ^_^
@1:06:00, no, a DC restoration circuit supposed to correct and regulate a perfect black level. The reason for the DC restoration circuit is that the RCA composite video source usually has a series cap when driving the video output so the on the monitor side where there is a 75ohm load to GND, minimal current is applied to that resistor. The DC restoration supposed to internally in the monitor clamp a reference black level to the video's black reference just after every H-Sync (known as the H-sync back porch). The black level issues you have been observing on cheap monitors come from either a poor DC restoration circuit design, or more likely poor regulation of the monitor's HV B+ output. I have in the past solved such dropping black levels by strategically adding a high voltage zener diode to one of the lower voltage taps on the flyback, completely elimination that shift in brightness at the expense of having the monitor's flyback transistor continuously working a little extra hard.
Thanks was just thinking up a reply on DC restoration, glad you beat me to it. I've bumper into so many cheap TV's that have no DC restoration, where the brightness is forever pumping as the scene changes - all to save a few cents. Yuk.
@@graemezimmer604 But more to overcome the effects of capacitive coupling, as composite video's bandwidth extends all the way down to DC (a solid white screen) so if you run video through a capacitor and jump from a mostly black screen, to a mostly white one, the displayed picture will be initially bright as intended, but quickly fades as the cap charges up.
My first guess was that this monitor was probably used in a hospital like a heart rate monitor. That instantly came into my mind when I heard that it's a medical device. But after you showed that the bezel was probably for mounting a camera for a ultrasound scanner that sounds perfectly makes sense too.
A friend of my cousin used to repair monitors such as this for HP back in the day when he and my cousin worked for HP's medical equipment division. When HP sold off that division to Phillips, he had a lucrative contract maintaining the monitors for remaining customers until they retired their equipment for modern equipment.
Yes I remember in UK 1970s when the BBC daily broadcast ended and played God Save the Queen, I would switch the TV off and get that bright white dot. It was a failure of a diode (possibly even a valve/tube rather than a silicon or germanium diode) to deflect the beam at switch off.
Yeah. I'm old school and and slightly turned-on with that turn-off dot. I don't mean to make "light" of it. Although it does put the spot-light on that issue. I'm just beaming with excitement that we're even talking about it. Just saying
When I got my own first TV as a kid in the 90s it was some B&W 15 inch tv. I loved the thing mostly how it had no Pixels compared to the color TVs. Played all my PS1 and SEGA games on it. My favorite part was turning it off and seeing the extremely bright dot glow for awhile after I turned the TV on and off after letting it charge up
I once had a Barco Graphics (an enormous beast of a CRT projector) back in the day that suffered from this issue. Had to replace the green tube because of dot burn-in and got sent a circuit board in addition that I solder to some points where the focus-adjustment knobs were located. That eliminated the turn-off dots completely.
Ive worked on very similar in the medical industry when I first started in the late eighties, ECG (EKG) were bouncing ball displays that faded to give the illusion of persistance like an oscilloscope, the distance between the different parts of the wave for the ecg can signify clinical data including the heart rate, you would need to be in the nice flat area. We would have to input a 60 bpm signal and then set up the span to be 75mm across 3 beats. An input box would act as interface and take the readings from the patient. we would regularly have to change the tubes as they would run 24 hrs a day and you would get bad phosphor burn on them. Now I feel really old! Great content thanks
7:10 those jacks are PL258/PL259. Literally a 4mm banana jack with shielding. I saw setups using bare 4mm jacks plus crocodiles for GND to feed signals.
@m1geo Also called UHF connectors, though they are useless for UHF use. They came around before UHF was really a thing, so you can forgive the naming. Used a lot on VHF wireless microphone systems.
In the early days of video, PL259 plugs were the standard, this moved to BNC on pro gear, with domestic quickly switching to RCA to save a few cents. I always prefered BNC for video, so you didn't get the video and audio leads mixed up.
For the gap between the bezel and the case (or the tube and the bezel or both) just get a thin strip of foam tape and put it around the edge. It will fill the gap seal it so stuff does not go in and also add a bit of cushion for movement.
I used to work in the test planning department at audio factory here in England and you'll be amazed the hybrids we made for testing stuff just using off the shelf equipment and amazingly sometime the customers would ask us to specifically make one of our own products in a unique way to suit their intended purpose.
I stepped in to this video being a guy who appreciates vintage equipment, but not giving a hoot about older security monitors like this one. I gave the video a go and I myself would like to see what you would do with this monitor. I have come across numerous custom shop jobs in my lifetime and this is just one of those that I have come across but never appreciated until now. The thought that a need was out there that some company had their team sit down and come up with a fix over beers and who knows how many packs of cigarettes just makes me appreciate the ingenuity even more. Most of us probably know that a lot of those cutting edge engineers not only didn't get credit, but probably didn't even get any return for that resistor value here, or that tap on the back of the monitor idea. Lots of development... Not much thought of where it came from. Keep up the content!
We still have a little B&W security monitor in the back of a storage closet at work, along with a camera and 24 hour VCR. It hasn't been used in 25 years, and I'd guess it all dates to the mid 80s.
i would try some solvent on the upper paint layer, if you're lucky the paint beneath is baked powder paint that wont solve.Powder paint is often used on metal chassis.
That looks like Polaroid sheet film which could be used in 4" x 5" view cameras using a special film holder. Commonly used by commercial photographers to check composition and exposure before the final shot on film.
There were a fair amount of companies modifying regular off the shelf TV's for medical devices until the big manufacturers entered the market. I have a Sony KV-1311CR from the mid 80s that was modified into a display for an arthroscope.
I'm glad you're happy with the scars on that monitor. I couldn't imagine the amount of video that screen has brought to the viewers of it over the years.. At first, early in the video i almost hoped there would be some burn-in (worst thing ever, i know sorry) but just, maybe if there was a permanent menu on the screen forever, you know.. you'd know for sure what it's use was.. but I think you've sleuthed it out pretty well Adrian. Great episode!!
A quick google (yeah, DDG just doesn't give the results I want), I found two ultrasound machines from the 70s called "Picker International" (turns out they were on the same ob-ultrasound website), and they both depict CRT monitors (not identical, but very similar to this one) placed on their side, so possibly this was a part of a baby-botherer machine... :)
I remember we had a Dunn Instruments device that had a CRT and a Polaroid camera that could give you color 8x10 pictures. It was quite a process to get a hardcopy!
The type of "peel apart" Polaroid film you are referring to is polaroid type 100 "packfilm" and its derivates. No longer made, this was the second major generation of polaroid film before the square framed "integral" SX-70 and 600 film. Polaroid had tons of films made for industrial applications and multiple generations of technology lived in parallel. A lot of oscilloscopes, Gel cameras etc used packfilm for its ease of use and ability to be xeroxed easily (compatible integral cameras were made too but less popular) also in rotation was the much larger and one shot type 54 which used the graphlex 4in x 5in standard, and for instant X ray applications the polaroid 8 x 10 system. This truly was Polaroids bread and butter, even more than their domestic uses.
I was watching something a while back about a medical computer. It was mentioned that a lot of medical devices because of service location end up getting almost single purpose one-off built or small batch built which causes them to have a fair wide variety of parts and the use of things. And this seems like it was definitely used for sonograms and may have even been rotated due to the way she operates. The brightness circuit might've actually been useful in a dark room to limit the sharp brightness of the input signal from the machine.
Wow, that brings back memories. Back in the day, I had a 12" Zenith amber phosphor composite monitor, & it was my main monitor through the 80s. 2:30 The giveaway here is that label saying "Toshiba Medical Systems" which means that it was originally a "machine that goes ping" from a hospital, so likely part of an EKG medical device.
CRT pro here: 6:27 DHEW rule 21 CFR sub chapter J is the federal X-Ray standards for CRTs. CFR = Code of Federal Regulations BTW - FCC regulations on interference emissions from electronic devices didn’t come into play until sometime in the 1980s
It was definitely a big deal in the '70s, as a lot of newfangled devices that could hook up to TVs had to jump through a lot of design hoops to get their products into compliance back then. It wasn't till a bit later that the FCC _relaxed_ these a bit after it became clear the limits were a bit unnecessarily tight. In fact the FCC goes back to 1934 and incorporated regulations about "harmful interference" from the start
@@TheGreatAtario The rules would have changed around '78. They weren't so strict in 1977 when the Trinity came out, but Atari had to do extensive work to comply with the new rules with their release of the Atari 400 and 800 in late 1979.
54:51 - that vertical deflection IC is probably a TDA1170, the tabs stick out on the sides like wings. That is so that the copper of the PCB can help serve as a heat sink, even when a discrete heat sink is used as you see on this IC when viewed from the top.
I was a field service engineer for Toshiba Medical Systems from 6/1981 until I retired in 5/2010. I saw one of those many years ago. Fairly certain it was a monitor on a very early Toshiba EKG machine. I don't think those monitors were made by us. I think they actually came from Techtronics. Were painted with our colors and our label glued to the front - hence the hint of blue paint. We made EKG stuff in the early 1980's, then again for a while in the mid-1990's. After that the EKG system was just a module built into the ultrasound machines. We used that beige color in the early 1980's. Afterwards we shifted to a blue color.
You could 3d print a couple of things to fix some of your annoyances. For one, you could print a spacer to go between the sheet metal front and the black plastic bezel. That would push the bezel back towards the CRT. Second, you could print a new plastic button for the existing power switch.
Ohh man, the old peel apart film!! Fun fact - the part you pulled off could be used as a negative in some occasions, mostly with the black and white though. I wish the stuff was still around because it was truly fantastic film.
Get some of that 1/4” wide door seal foam. Apply it to the perimeter of the bezel and put it all back together. That format will compress against the rolled edges and keep the whole assembly tight and rattle free.
Adrian, Dawn powerwash spray will remove spraypaint very easily, Spray it on, let it sit for a while, i think its like 20 minutes, spray it again, and use something plastic to scrape the now loose spraypaint off, leaving the original finish behind. Works on miniatures and RC stuff.
My daughter is a bio-med engineer, and it is a common thing for hospitals where she works, to put those extremely expensive connectors on equipment that is used in special locations.
Interesting tube, I have a feeling it was repainted white to be used in a hospital ward, because hospitals generally dislike when equipment isn't a sterile colour. You might be able to get the original paint back with some light acetone if you are careful with it. it is of a high liklihood that the composition of the cream layer of paint is not embedded particularly deeply and that it will not tarnish the blue layer severely to remove the lighter layer, but take it slowly if you do.
As soon as i saw that plastic bezel, that looks like it could have a cover i was thinking industrial display of some sort. Many of those, even today with non-CRT displays in them have waterproof covers to try and minimize environmental damage. But it seems from the comments below that it is some sort of medical display. Which is also pretty cool!
Original coil mounted on the side PCB is a linearity for H deflection, it is set by adjusting it to max width then turning so left side starts to compress. The vertical deflection ic is probably a TDA1170.
51:20 - the ringing on the left side of the screen is probably due to either the damper diode, or the flyback transformer. With a linearity coil being the next suspect, assuming there is a linearity coil being used. A linearity coil is usually wire wound on an I-shaped piece of ferrite, with a permanent magnet attached to the piece of ferrite.
38:57 - the original bezel was put back because it matched the curvature of the CRT faceplate. The sheet metal that was used wouldn’t do that. This prevents objects (like coins) from falling inside the unit.
Funny. I was thinking who painted that (two tone) Blue? It may be the same reason a company will paint their "rental trailers or equip" some gosh awful bright orange or green etc. EZ spotting and to dissuade (yes I said dissuade) folks from stealing them. I just think that's a little nasty. Which ironically is what my last GF told me before she finally left. That's just my 8 cents ( inflation )
@@ValuedTeamMember That blue was the standard corporate color dress for GBC. I used to have a few GBC cameras that were the same color. They were based on Vidicon tubes and the power transformers inside had cloth covered wire.
Interesting, thanks. Depending on how much room there actually was behind the tube/chassis, I think I'd have put the plastic/insulator on the chassis itself, vs. the board. Easier to glue/fasten on securely as well as not in the way if working on the monitor.
I have one 12" made by philips, its a white phosphor tube and at the front theres a slot to slide in coloured acetate sheets to change the screen colour, orange, green and blue, its pretty neat and has an awesome picture, very similar principle to the VECTREX tube yours was used in dentists to display x-rays
I find it rather interesting that so many mods were done to this monitor instead of just making a new variant. Probably was still cheaper to just mod the existing variant. I can't imagine that a lot of the modded ones were sold.
I have one of those attachments you mentioned early in the video. New old stock. The thing that goes on to the bezel and then to a camera for taking photos. I was hoping to find a good home for it.
Hospitals have engineering departments and it is def possible that that thing was customized by hospital staff. That big honking plug was on every piece of hospital equipment even when I was working in hospitals 20 years ago.
I'm pretty sure that, in my parents' stash of stuff from mine and my brother's childhood, they have a picture of an ultrasound from one of us that looks _exactly_ like the polaroid pictures you showed. We were both born in the early 80s. I had no idea that's how it was done.
A point about terminology: Adjusting the brightness of the whites is not "DC restoration". DC restoration is something done to an AC coupled video signal so that the black level is in the right place. It doesn't change the amplitude. What you're talking about is more of an automatic contrast control.
I would be all for another video of this. And if the power switch is unobtainium or too expensive, maybe a different switch with a little light in it would be nice, since the monitor doesn't have a power light of its own,
Adrian I'm an "old fart" (70 +) and remember the diminishing dot occurring whenever the TV was turned off at "bedtime". And kids being kids we would sit glued to the box till all signs of illumination were extinct before reluctantly going through the bath bed routine. I don't recall any burn in of the screen from this. Cheers Eric
54:21 - the two jacks are wired together to allow that single video source to feed multiple display monitors (AKA daisy chain). There should be a switch to enable or disable the 75 ohm termination; to daisy chain, only the last monitor on the chain is terminated, all other monitors on the chain would be unterminated by the switch setting.
Adrian, you could really go down a rabbit hole of doing videos on the interesting modifications of computers and peripherals like this one that were used in the medical industry. For example, older electromyography/nerve conduction study machines were just modified oscilloscopes and later were portable computer or early laptop modifications with special peripherals for performing the medical tests. You may not be able to restore all the medical functionality due to proprietary OSs and ROMs, but even just a teardown to see what CPUs etc are under the hood would still be interesting. I, for one, would be interested in seeing more videos of this sort.
Hospitals require very specific plugs on all equipment. So whatever plug might have been on there may very well have been cut off and that high quality plug added after the fact to make it hospital compliant.
GBC had that logo trademarked in 1979 using a correspondence address of 280 HUYLER STREET SOUTH HACKENSACK, NJ. It's a small lab / industrial building that looks much more like where the actual manufacturing would have taken place
48:25 the dot used to be called a squarf. newer CRTs eliminated it with some additional circuitry since it would cause premature phosphor wear in that central spot. it would be a dark spot burned in.
BNC. We still use this connector today with medical scopes. I work in the GI field and hate BNC connectors. They are generally too loose and if you touch the wire the signal breaks. You have to smash them a bit to get a good connection.
Radwell are legit. We use them all the time at work. If they say they have it then they do somewhere. They’re very expensive, but they guarantee everything they sell.
I would love to see a tutorial for re-finishing the paint on this king of thing. I have a lot of old banged up metal enclosures for things like this that I would love to know how to go about stripping the paint and re-coating it all.
6:54 "UHF" connectors. PL-259 (plug) or SO-259 (socket) was the official type. In the 1970's there were special 1" video tape recorders, like an IVC 1010, for medical imaging that did 1,000 lines of resolution. I need to watch the rest of this episode but it'd be interesting to come across a high-res monochrome video monitor like that.
The Toshiba GBC MV-10A is a lesser-known CRT display, often associated with vintage gaming and computing setups. As a CRT monitor, it typically offers characteristics like deep colors, good contrast, and low input lag, making it popular among retro gaming enthusiasts. The MV-10A is particularly noted for its versatile compatibility with various resolutions, making it suitable for gaming consoles from the era, as well as older computer systems. Collectors and tech enthusiasts often seek these displays for their unique visual quality and nostalgia factor, but finding detailed specifications or documentation can be challenging due to their age and limited production. Fans of CRT technology frequently share insights and restoration tips in online communities, helping to keep interest in models like the MV-10A alive.
I just realized why I bet they used a shrunken pic on a larger crt. I bet it was to make use of the flattest part of it so there was no distortion at the corners since distance in the ultrasound image was critical.
and black and white screen, so there is a dot-screen mask? and going to an optical film camera anyway, and that most have it with lens optics too; the full screen was so large all ready, so idealy a smaller CRT might be better? but may not have exsisted, and if did, there sosable not ruged and sell biuld for left 24/7 everyday for years, the cheaply available sercurity monoyor where, and being ready market sellers, and good enuth is good enuth they just when the readyly available cheaper option than something made in house
Yeah they're sort of approximating a scope tube with the lower deflection angles for higher precision, but with a shallower tube, a real scope tube that size would be much longer and might not fit where ever they put it (also, cheaper)
That and the film frame was square, so yeah you wanted to use the centermost part of the screen for the least distortion. Ultrasound machine at the time weren't fully digital and couldn't crop the image to the center of the frame, so the simplest thing was to modify the monitor.
GBC is "Gian Bruto Castelfranchi", it was an italian company and they had a division overseas. Usually they sold rebranded TVs and monitors, their main business was sold spare parts btw.
Pretty sure that the bezel had the purpose to mount a camera to take pics of the screen, like some scopes in the 60's and 70's
@@Telewaifus Those were Polaroid cameras for instant images, printers were not able to output the necessary quality for a long time.
Yes, I remember this company logo here in Italy when I was young. In a GBC shop that sold electronics my brother bought a ROM cartridge for our TI99/4A :)
In regards to your closing comments, Adrian, I'm pretty sure we're all here to see the repairs, so anything you think anybody might find interesting, definitely post it to one of your channels!
DHEW was the Dept of Health, Education and Welfare, the predecessor to HHS and defunct in 1979 when Education was split off on its own.
Hmm why do you think a video monitor might have that marking on it? (Even the non medical one had that in the photos)
@@adriansdigitalbasement FDA Rule 21 Subchapter J (marked here as a DHEW [now DHHS] rule; the FDA was/is under DHEW/DHHS) has to do with regulating radiological emissions from electronic equipment.
@@adriansdigitalbasement 21 CFR Subchapter J focuses on Radiological Health and includes regulations related to electronic products that emit radiation. Whereas FCC covers RF interference, my guess is DHHS and DHEW covers human safety
Do you suppose "CER" is an old term for what we know now as "CFR", or was it a typo? I'm guessing the latter, which is weird.
@@adriansdigitalbasement I imagine this monitor was sold as a part of or add-on for the scanner. So being sold for use in a medical environment, it would be considered medical equipment.
My assumption is that Toshiba used GBC as a monitor supplier for their medical devices. They resprayed already existing monitors to beige to match the rest of Toshiba's equipment.
high end Japanese equipment of the era was bodgy but not THIS bodgy.
I think Toshiba just marked it up 10x because "medical device" and replacement part was out of budget for the end user, so they went and found some handymen who made a good enough replica of the original monitor.
Yep. Medical equipment is filled with rebadged electronics. Famously the CRT Olympus OEV monitors are rebadged Sony PVMs.
Its a lot easier for the Hospital, Supplier, Technicians exc if a device with multiple parts is sold, serviced, and warrantied as 1 complete 'Unit' rather then the customer having to deal with each individual company if a part breaks.
@denisdrozdoff2926
The Bodgy nature of this example likely comes from a 3rd party medical supplier's repair services. My old Boss used to fix medical equipment thats support was discontinued from the manufacturer. Stuff like this can be in the field for 20+ years and prior to the internet trying to source an exact part of a discontinued machine like could be difficult and more costly then adapting another tube to the chassis.
@@denisdrozdoff2926 Toshiba MRI was one of my consulting clients. I don't think you have a clear picture.
Adrian's Analog Basement - Great video, I really enjoy these monitor shenanigans, not many retro computing enthusiasts actually get into that topic. :)
Please Adrian change your channel name to something like Adrian’s digital & analog basement or Adrian’s analog basement
Make a third channel called Adrian’s analog basement. Also I was literally thinking about commenting that on a crt video yesterday!
Yes
@@AsherJohnson-k1i Adrian’s electronics basement?
@diskettenfett3161 maybe
back when screenshots were shots of the screen
and cutting and pasting required scissors and glue...
And the PrintScreen key printed what was on the screen :v
7:04 Those are SO-239 connectors, which mate with [EDIT]PL-259 plugs. Also called "UHF" connectors, despite being totally unsuitable for use much above 100MHz.
PL-259
@@adagioleopard6415 Yes, you're right. I referred to my old 1976 ARRL handbook and found the plug referred to as a "PL-259," as well as an "83-1SP."
I think when they were created, 100MHz would have been considered "UHF" :)
@@tr0gd0r04-z1l Even back then, UHF started at 300Mhz :)
@@tr0gd0r04-z1l Could be!
Had someone told me I would watch with rapt attention a video about 45 year old analog tech I would have laughed.
You sir are a master teacher and storyteller.
Cheers from Canada!
@1:03:15, the 60hz bend you see might not be EMF, but, an actual magnetic field coming from the monitor's mains transformer interfering with the deflection on the CRT. Otherwise, it may be a dying decoupling cap for the yoke's deflection driver IC's power supply.
To avoid the effects of the magnetic field generated by the monitor's main power transformer, the transformer is positioned at approximately 45 degree angle.
Yeah, but it was virtually impossible to completely eliminate the Hum Bar. The other trick was to put a band of copper tape around the outside of the transformer to short out any external field.
And that "60hz bend" was known as a "Hum Bar".
Adrian, you DO have a job. Your job is to share your electronics and retrocomputing knowledge with us, and you're pretty good at it. 😉
I love seeing hand drawn circuit boards. Good memories from childhood when we’d get copper coated boards from Radio Shack and resist pens / rub down film to make them for projects.
Did you use ferric chloride to etch the boards, or the white ammonium stuff?
@ I don’t remember. It was just some dark brown liquid from what I can remember. In college for an art class, I did some photo etching and that was completely different. Very toxic stuff. The professor was surprised I could just buy it from an electronics shop. It probably was, but at 19 were all invincible.
such an exciting video! I was so thankful at 36 minutes when you decided to open those back screws like I had been begging for you to do for 5 minutes ^_^
@1:06:00, no, a DC restoration circuit supposed to correct and regulate a perfect black level. The reason for the DC restoration circuit is that the RCA composite video source usually has a series cap when driving the video output so the on the monitor side where there is a 75ohm load to GND, minimal current is applied to that resistor. The DC restoration supposed to internally in the monitor clamp a reference black level to the video's black reference just after every H-Sync (known as the H-sync back porch). The black level issues you have been observing on cheap monitors come from either a poor DC restoration circuit design, or more likely poor regulation of the monitor's HV B+ output. I have in the past solved such dropping black levels by strategically adding a high voltage zener diode to one of the lower voltage taps on the flyback, completely elimination that shift in brightness at the expense of having the monitor's flyback transistor continuously working a little extra hard.
Thanks was just thinking up a reply on DC restoration, glad you beat me to it. I've bumper into so many cheap TV's that have no DC restoration, where the brightness is forever pumping as the scene changes - all to save a few cents. Yuk.
Yes, DC Restoration was intended to fix drifting in the RF Detector, when the "Black Level" moved due to AGC clamping problems..
@@graemezimmer604 But more to overcome the effects of capacitive coupling, as composite video's bandwidth extends all the way down to DC (a solid white screen) so if you run video through a capacitor and jump from a mostly black screen, to a mostly white one, the displayed picture will be initially bright as intended, but quickly fades as the cap charges up.
My first guess was that this monitor was probably used in a hospital like a heart rate monitor. That instantly came into my mind when I heard that it's a medical device.
But after you showed that the bezel was probably for mounting a camera for a ultrasound scanner that sounds perfectly makes sense too.
It probably wasn't laying on its side, but was probably placed right next to another piece of equipment and the feet provided space for airflow.
A friend of my cousin used to repair monitors such as this for HP back in the day when he and my cousin worked for HP's medical equipment division. When HP sold off that division to Phillips, he had a lucrative contract maintaining the monitors for remaining customers until they retired their equipment for modern equipment.
Always been “Philips” now. I remember Phillips as well. Supposedly it’s a well known Mandela Effect.
@@nyccollin Mandela Effect, nope not this time. I got the spelling mixed up. My gut said Philips, but I went with Phillips.
@@Clavichordist Yeah just saying that it comes up a lot. Trust your memories.
@@nyccollin Indeed. The gut us usually right just like when we take multiple choice tests. ;-)
That turn-off dot was very common on many B&W TVs back in a day.
Yes I remember in UK 1970s when the BBC daily broadcast ended and played God Save the Queen, I would switch the TV off and get that bright white dot. It was a failure of a diode (possibly even a valve/tube rather than a silicon or germanium diode) to deflect the beam at switch off.
Yeah. I'm old school and and slightly turned-on with that turn-off dot. I don't mean to make "light" of it. Although it does put the spot-light on that issue. I'm just beaming with excitement that we're even talking about it. Just saying
When I got my own first TV as a kid in the 90s it was some B&W 15 inch tv. I loved the thing mostly how it had no Pixels compared to the color TVs. Played all my PS1 and SEGA games on it. My favorite part was turning it off and seeing the extremely bright dot glow for awhile after I turned the TV on and off after letting it charge up
I once had a Barco Graphics (an enormous beast of a CRT projector) back in the day that suffered from this issue. Had to replace the green tube because of dot burn-in and got sent a circuit board in addition that I solder to some points where the focus-adjustment knobs were located. That eliminated the turn-off dots completely.
@@SilverXTikal This was bad and fecked up your CRT. It was deinitely eliminated when colour TVs became a thing. But could also be a fault.
that power switch was called a shadow switch.
Ive worked on very similar in the medical industry when I first started in the late eighties, ECG (EKG) were bouncing ball displays that faded to give the illusion of persistance like an oscilloscope, the distance between the different parts of the wave for the ecg can signify clinical data including the heart rate, you would need to be in the nice flat area. We would have to input a 60 bpm signal and then set up the span to be 75mm across 3 beats. An input box would act as interface and take the readings from the patient. we would regularly have to change the tubes as they would run 24 hrs a day and you would get bad phosphor burn on them. Now I feel really old! Great content thanks
I love your videos, especially when you pull out this kind of prehistoric equipment and bring it back to life
7:10 those jacks are PL258/PL259. Literally a 4mm banana jack with shielding. I saw setups using bare 4mm jacks plus crocodiles for GND to feed signals.
The sockets are SO239. The plugs are PL259.
@m1geo Also called UHF connectors, though they are useless for UHF use. They came around before UHF was really a thing, so you can forgive the naming.
Used a lot on VHF wireless microphone systems.
Are you sure? PL258 is 50 Ohm. Is this monitor connector 50 Ohm too?
@@Qyonek See the video termination switch. 50 Ohms.
@@zaprodk missed that, thanks!
The numeric designator for those connectors is PL-259. It is frequently called a "UHF connector". You do find some interesting toys, man! 😁
In the early days of video, PL259 plugs were the standard, this moved to BNC on pro gear, with domestic quickly switching to RCA to save a few cents.
I always prefered BNC for video, so you didn't get the video and audio leads mixed up.
Yes! More digging into CRT stuff
For the gap between the bezel and the case (or the tube and the bezel or both) just get a thin strip of foam tape and put it around the edge. It will fill the gap seal it so stuff does not go in and also add a bit of cushion for movement.
Those connectors are called SO-239, the matching plugs are PL-259
I used to work in the test planning department at audio factory here in England and you'll be amazed the hybrids we made for testing stuff just using off the shelf equipment and amazingly sometime the customers would ask us to specifically make one of our own products in a unique way to suit their intended purpose.
I stepped in to this video being a guy who appreciates vintage equipment, but not giving a hoot about older security monitors like this one. I gave the video a go and I myself would like to see what you would do with this monitor. I have come across numerous custom shop jobs in my lifetime and this is just one of those that I have come across but never appreciated until now. The thought that a need was out there that some company had their team sit down and come up with a fix over beers and who knows how many packs of cigarettes just makes me appreciate the ingenuity even more. Most of us probably know that a lot of those cutting edge engineers not only didn't get credit, but probably didn't even get any return for that resistor value here, or that tap on the back of the monitor idea. Lots of development... Not much thought of where it came from.
Keep up the content!
The connectors on the back are SO239, their male counter is a PL259. They are used extensively in HAM and CB radio.
We still have a little B&W security monitor in the back of a storage closet at work, along with a camera and 24 hour VCR. It hasn't been used in 25 years, and I'd guess it all dates to the mid 80s.
i would try some solvent on the upper paint layer, if you're lucky the paint beneath is baked powder paint that wont solve.Powder paint is often used on metal chassis.
That looks like Polaroid sheet film which could be used in 4" x 5" view cameras using a special film holder. Commonly used by commercial photographers to check composition and exposure before the final shot on film.
1:02:44 the non-leaking cap is one order of magnitude _out_ of spec (88.8 Ohm vs 8.5 Ohm in the table), so good to have swapped them anyways!
There were a fair amount of companies modifying regular off the shelf TV's for medical devices until the big manufacturers entered the market. I have a Sony KV-1311CR from the mid 80s that was modified into a display for an arthroscope.
You're becoming my favorite crt channel, despite not being the main topic of it😅
The blue ones would look great on an Altair
Yeah that would fit nicely on an Altair
Love the recent crt monitor special thrill fixing ! Flat-screen, doesn't have this crt becoming very rare today !
I'm glad you're happy with the scars on that monitor. I couldn't imagine the amount of video that screen has brought to the viewers of it over the years.. At first, early in the video i almost hoped there would be some burn-in (worst thing ever, i know sorry) but just, maybe if there was a permanent menu on the screen forever, you know.. you'd know for sure what it's use was.. but I think you've sleuthed it out pretty well Adrian. Great episode!!
Try sticking some package tape on the paint and pull it off again. That sometimes works to remove the top layer.
A quick google (yeah, DDG just doesn't give the results I want), I found two ultrasound machines from the 70s called "Picker International" (turns out they were on the same ob-ultrasound website), and they both depict CRT monitors (not identical, but very similar to this one) placed on their side, so possibly this was a part of a baby-botherer machine... :)
I remember we had a Dunn Instruments device that had a CRT and a Polaroid camera that could give you color 8x10 pictures. It was quite a process to get a hardcopy!
At work, we dealt with Radwell one time when we were in a pinch. They were really good to deal with.
that was actually super interesting! puts back the screen and the shot in screenshot!
Adrian Holmes! You need a pipe and spyglass for true authenticity. I love those old tear downs and repairs. Much more visual than software issues!
You can get paint matched at home Depot or Lowe's to the blue paint and then repaint the outside that color
The type of "peel apart" Polaroid film you are referring to is polaroid type 100 "packfilm" and its derivates. No longer made, this was the second major generation of polaroid film before the square framed "integral" SX-70 and 600 film. Polaroid had tons of films made for industrial applications and multiple generations of technology lived in parallel. A lot of oscilloscopes, Gel cameras etc used packfilm for its ease of use and ability to be xeroxed easily (compatible integral cameras were made too but less popular) also in rotation was the much larger and one shot type 54 which used the graphlex 4in x 5in standard, and for instant X ray applications the polaroid 8 x 10 system. This truly was Polaroids bread and butter, even more than their domestic uses.
Yes, I went through hundreds of packs of Polaroid Film in the 70's, documenting the peformance of long-line video circuits for the telephone company.
I was watching something a while back about a medical computer. It was mentioned that a lot of medical devices because of service location end up getting almost single purpose one-off built or small batch built which causes them to have a fair wide variety of parts and the use of things. And this seems like it was definitely used for sonograms and may have even been rotated due to the way she operates. The brightness circuit might've actually been useful in a dark room to limit the sharp brightness of the input signal from the machine.
Wow, that brings back memories. Back in the day, I had a 12" Zenith amber phosphor composite monitor, & it was my main monitor through the 80s.
2:30 The giveaway here is that label saying "Toshiba Medical Systems" which means that it was originally a "machine that goes ping" from a hospital, so likely part of an EKG medical device.
CRT pro here: 6:27 DHEW rule 21 CFR sub chapter J is the federal X-Ray standards for CRTs.
CFR = Code of Federal Regulations
BTW - FCC regulations on interference emissions from electronic devices didn’t come into play until sometime in the 1980s
It was definitely a big deal in the '70s, as a lot of newfangled devices that could hook up to TVs had to jump through a lot of design hoops to get their products into compliance back then. It wasn't till a bit later that the FCC _relaxed_ these a bit after it became clear the limits were a bit unnecessarily tight. In fact the FCC goes back to 1934 and incorporated regulations about "harmful interference" from the start
@@TheGreatAtario The rules would have changed around '78. They weren't so strict in 1977 when the Trinity came out, but Atari had to do extensive work to comply with the new rules with their release of the Atari 400 and 800 in late 1979.
On the board where the horizontal width adjustment is there's a spot above the main adjustment which is where the extra coil went.
The video input jacks are UHF PL and SO connectors (The PL259 is the male connector and the SO239 is the female connector.)
54:51 - that vertical deflection IC is probably a TDA1170, the tabs stick out on the sides like wings. That is so that the copper of the PCB can help serve as a heat sink, even when a discrete heat sink is used as you see on this IC when viewed from the top.
Resistance in serial is additive, but resistance is parallel averages the two values. A little nugget for you.
I was a field service engineer for Toshiba Medical Systems from 6/1981 until I retired in 5/2010. I saw one of those many years ago. Fairly certain it was a monitor on a very early Toshiba EKG machine. I don't think those monitors were made by us. I think they actually came from Techtronics. Were painted with our colors and our label glued to the front - hence the hint of blue paint. We made EKG stuff in the early 1980's, then again for a while in the mid-1990's. After that the EKG system was just a module built into the ultrasound machines. We used that beige color in the early 1980's. Afterwards we shifted to a blue color.
You could 3d print a couple of things to fix some of your annoyances. For one, you could print a spacer to go between the sheet metal front and the black plastic bezel. That would push the bezel back towards the CRT. Second, you could print a new plastic button for the existing power switch.
@ ~ 47:20 , note that those SO-239 UHF connectors can take a standard 4mm banana plug into the center conductor, if you need to
Ohh man, the old peel apart film!! Fun fact - the part you pulled off could be used as a negative in some occasions, mostly with the black and white though. I wish the stuff was still around because it was truly fantastic film.
Get some of that 1/4” wide door seal foam. Apply it to the perimeter of the bezel and put it all back together.
That format will compress against the rolled edges and keep the whole assembly tight and rattle free.
As someone who has had countless numbers of medical scans done, I could immediately tell what it was.
Adrian, Dawn powerwash spray will remove spraypaint very easily, Spray it on, let it sit for a while, i think its like 20 minutes, spray it again, and use something plastic to scrape the now loose spraypaint off, leaving the original finish behind. Works on miniatures and RC stuff.
That connector is a SO-239. And you're right, it's still used for RF connections with CB and Ham radio stuff.
My daughter is a bio-med engineer, and it is a common thing for hospitals where she works, to put those extremely expensive connectors on equipment that is used in special locations.
Interesting tube, I have a feeling it was repainted white to be used in a hospital ward, because hospitals generally dislike when equipment isn't a sterile colour. You might be able to get the original paint back with some light acetone if you are careful with it. it is of a high liklihood that the composition of the cream layer of paint is not embedded particularly deeply and that it will not tarnish the blue layer severely to remove the lighter layer, but take it slowly if you do.
As soon as i saw that plastic bezel, that looks like it could have a cover i was thinking industrial display of some sort. Many of those, even today with non-CRT displays in them have waterproof covers to try and minimize environmental damage. But it seems from the comments below that it is some sort of medical display. Which is also pretty cool!
47:33 - Tech Tip: a banana plug will fit into those video connectors.
As has been mentioned, the connectors are SO293 types. For a quick servicing tip, the centre pin is 4 mm, so a banana plug fits them.
Andy
Nice archaeology adventure! "Adriana Jones exploring the Tube of Doom..." 😊
+1 for seeing the mods done!
Original coil mounted on the side PCB is a linearity for H deflection, it is set by adjusting it to max width then turning so left side starts to compress.
The vertical deflection ic is probably a TDA1170.
51:20 - the ringing on the left side of the screen is probably due to either the damper diode, or the flyback transformer. With a linearity coil being the next suspect, assuming there is a linearity coil being used. A linearity coil is usually wire wound on an I-shaped piece of ferrite, with a permanent magnet attached to the piece of ferrite.
38:57 - the original bezel was put back because it matched the curvature of the CRT faceplate. The sheet metal that was used wouldn’t do that. This prevents objects (like coins) from falling inside the unit.
GBC produced CCTV monitor and cameras, mostly for surveilance
"Who painted this beige?" I mean, who doesn't paint their electronics beige?
Well I painted a beige BBC B 3.5" drive black to match my Spectrum 128 and Disciple interface. 🙂
certainly for medical system, the blue would stand out, the beige blends in
@@jyvben1520I don’t think it’s about blending in. It’s about showing stains that would not be as obvious on dark colors.
Funny. I was thinking who painted that (two tone) Blue? It may be the same reason a company will paint their "rental trailers or equip" some gosh awful bright orange or green etc. EZ spotting and to dissuade (yes I said dissuade) folks from stealing them. I just think that's a little nasty. Which ironically is what my last GF told me before she finally left. That's just my 8 cents ( inflation )
@@ValuedTeamMember That blue was the standard corporate color dress for GBC. I used to have a few GBC cameras that were the same color. They were based on Vidicon tubes and the power transformers inside had cloth covered wire.
Great video thank you. Would be interested in seeing the mods you mentioned in another video
Love these crt videos, so interesting
Interesting, thanks. Depending on how much room there actually was behind the tube/chassis, I think I'd have put the plastic/insulator on the chassis itself, vs. the board. Easier to glue/fasten on securely as well as not in the way if working on the monitor.
I have one 12" made by philips, its a white phosphor tube and at the front theres a slot to slide in coloured acetate sheets to change the screen colour, orange, green and blue, its pretty neat and has an awesome picture, very similar principle to the VECTREX tube
yours was used in dentists to display x-rays
I find it rather interesting that so many mods were done to this monitor instead of just making a new variant. Probably was still cheaper to just mod the existing variant. I can't imagine that a lot of the modded ones were sold.
Another CRT rescued. Love it.
I love the august burns red background! Great music!
I have one of those attachments you mentioned early in the video. New old stock. The thing that goes on to the bezel and then to a camera for taking photos. I was hoping to find a good home for it.
That connector is SO-239, its matching counterpart is PL-259 :)
Hospitals have engineering departments and it is def possible that that thing was customized by hospital staff. That big honking plug was on every piece of hospital equipment even when I was working in hospitals 20 years ago.
I'm pretty sure that, in my parents' stash of stuff from mine and my brother's childhood, they have a picture of an ultrasound from one of us that looks _exactly_ like the polaroid pictures you showed. We were both born in the early 80s. I had no idea that's how it was done.
A point about terminology: Adjusting the brightness of the whites is not "DC restoration". DC restoration is something done to an AC coupled video signal so that the black level is in the right place. It doesn't change the amplitude. What you're talking about is more of an automatic contrast control.
I would be all for another video of this. And if the power switch is unobtainium or too expensive, maybe a different switch with a little light in it would be nice, since the monitor doesn't have a power light of its own,
Adrian I'm an "old fart" (70 +) and remember the diminishing dot occurring whenever the TV was turned off at "bedtime". And kids being kids we would sit glued to the box till all signs of illumination were extinct before reluctantly going through the bath bed routine. I don't recall any burn in of the screen from this.
Cheers Eric
54:21 - the two jacks are wired together to allow that single video source to feed multiple display monitors (AKA daisy chain). There should be a switch to enable or disable the 75 ohm termination; to daisy chain, only the last monitor on the chain is terminated, all other monitors on the chain would be unterminated by the switch setting.
Adrian, you could really go down a rabbit hole of doing videos on the interesting modifications of computers and peripherals like this one that were used in the medical industry. For example, older electromyography/nerve conduction study machines were just modified oscilloscopes and later were portable computer or early laptop modifications with special peripherals for performing the medical tests. You may not be able to restore all the medical functionality due to proprietary OSs and ROMs, but even just a teardown to see what CPUs etc are under the hood would still be interesting. I, for one, would be interested in seeing more videos of this sort.
It's the misbegotten offspring of the forbidden love between an oscilloscope and a quad splitter!
Hospitals require very specific plugs on all equipment. So whatever plug might have been on there may very well have been cut off and that high quality plug added after the fact to make it hospital compliant.
GBC had that logo trademarked in 1979 using a correspondence address of 280 HUYLER STREET SOUTH HACKENSACK, NJ. It's a small lab / industrial building that looks much more like where the actual manufacturing would have taken place
43:33 I see a tab out there and I wanted painted black….. 😂
48:25 the dot used to be called a squarf. newer CRTs eliminated it with some additional circuitry since it would cause premature phosphor wear in that central spot. it would be a dark spot burned in.
BNC. We still use this connector today with medical scopes. I work in the GI field and hate BNC connectors. They are generally too loose and if you touch the wire the signal breaks. You have to smash them a bit to get a good connection.
Radwell are legit. We use them all the time at work. If they say they have it then they do somewhere. They’re very expensive, but they guarantee everything they sell.
I would love to see a tutorial for re-finishing the paint on this king of thing.
I have a lot of old banged up metal enclosures for things like this that I would love to know how to go about stripping the paint and re-coating it all.
6:54 "UHF" connectors. PL-259 (plug) or SO-259 (socket) was the official type.
In the 1970's there were special 1" video tape recorders, like an IVC 1010, for medical imaging that did 1,000 lines of resolution.
I need to watch the rest of this episode but it'd be interesting to come across a high-res monochrome video monitor like that.
The Toshiba GBC MV-10A is a lesser-known CRT display, often associated with vintage gaming and computing setups. As a CRT monitor, it typically offers characteristics like deep colors, good contrast, and low input lag, making it popular among retro gaming enthusiasts. The MV-10A is particularly noted for its versatile compatibility with various resolutions, making it suitable for gaming consoles from the era, as well as older computer systems. Collectors and tech enthusiasts often seek these displays for their unique visual quality and nostalgia factor, but finding detailed specifications or documentation can be challenging due to their age and limited production. Fans of CRT technology frequently share insights and restoration tips in online communities, helping to keep interest in models like the MV-10A alive.