Rejuvenating a color CRT
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- Опубликовано: 29 ноя 2022
- Our dumpster rescue Sony Trinitron monitor is very tired and all purple. Can we bring it back to life with CRT rejuvenation?
Previous video explaining CRTs: • Cathode Ray Tubes: inv...
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I've had mixed results rejuvenating CRTs, the main thing I've learned is to quit while you're ahead. If you get improvement doing it once it's tempting to try hitting it again but in my experience that usually leaves you worse off than when you started. I've never tried rejuvenating a Trinitron but I always heard they did not respond well to it.
Do any of them ever last for any length of time though?
shango066 says never rejuvenate a Trinitron.
radiotvphononut as well ...
@@wishusknight3009 Yes, sometimes, I've seen them go a few more years. If it's something like a TV that you're using for hours a day you'll probably buy a few months at best but for less used stuff like vintage equipment it can be significant.
@@fostercathead If it is still useable then yes, but a tube in this bad state you really have absolutely nothing to lose.
In Trinitrons and most recent CRTs the gap between the electrodes is quite small , so there's a good risk to end up with a short circuit. A workaround is to lower the high voltage and increase the max current to literally blow out the impurities. It's still quite like Russian roulette though
Thanks for the stroll down memory lane! I used to work on a lot of Sony PVM’s and BVM broadcast color critical displays back in the day. I’ve been in post production since I was a wee engineering boy in San Francisco in the mid 90’s, and I haven’t got to play with actual electronics repair in way too long! The “fun” displays were the BVM-D24, HD tube monitors. We replaced the tubes in those usually every 3-6 months at a cost of around $30k/each. The tubes never lasted due to how hard they had to drive them to get a 100 nit uniform display.
Why $o much?
@@robertgift two reasons: quantity and quality.
The post production / broadcast TV industry did not require a substantial quantity of these picture tubes. I'd guess that Sony only ever made on the order of 10's of thousands of the BVM-D24 HD displays (maybe even touching the 100k mark?)
Quality was the other issue where we would often reject a tube for the smallest of defects. Nothing short of a perfect tube was allowed since we used these to grade (color correct) images for film and TV, and color correction decisions were made based on what was seen on the display.
Color uniformity and geometry had to be absolutely perfect on all areas of the display for us to create the quality film transfers and 'home video' HD grades of the time. For example, we'd charge our clients something around $800-$1000/hr for our high end colorists and color correction services.
I recall speaking with the Sony engineers about these tubes, and only a small fraction of the tubes they manufactured would make it to the end user. Thus the cost was... substantial... to say the least.
These days we use the Sony BVM-X300 and BVM-X310 series OLED displays, which are 1000 nit UHD/4k HDR, and these still cost upwards of $30k, but they last orders of magnitude longer than the HD tubes ever did!
The high-end reference monitors always come at a cost, but you get absolute quality and as close to perfection as you can get, which is a requirement when you are creating content.
I've done many a tube with my home-built tester / rejuvenator which is based on a design printed in Television Magazine. Mine added a feature to disconnect the heater during the process, idea being that it would cool down: Smaller cathodes cooled down quickest so reduced the chance of stripping. Some tubes lost the plot again within some hours, most lasted months or years. So rarely did I do Trinitrons that I can't remember if I had any luck with those, I suspect not. Another useful tool was a home-made 25kV EHT meter which I would use to discharge the final anode before connecting up the rejuvenator. I remember that a couple of times a year we would visit an ex's relatives and I would "boost" their old TV. This carried on for some years before she dumped me. The relatives then "accidentally dropped" the TV and claimed on their insurance for a replacement.
Neat! There was a rejuvenator in the workshop where I worked; in the 6 years I was there I never saw it used.
Do you remember what issue the design was in?
I have reactivated many CRTs over years with a B&K 467. It really depends on how you operate these and many Techs do not know how to use them properly. I know many tubes have been killed by Techs who think they know what they are doing!
The B&K 467 has specific instructions, follow these and you will be more successful. I have reactivated many Sony Trinitron tubes and they have come back to life very well. Some tubes of course do not have much emmision coating left so not great results there.
I recall my uncle had a 22" Sony TV which lost its green too. After reactvation, it lasted 6 years! Its important to clean & balance ( the lowest gentle setting on the B&K) the other guns too at the same time to get a balanced result.In fact use this gentle setting ro start with and you may find thats all you need. The rejuvenate setting us much stronger and really is only required if the CRT dies not respond on the clean & balance setting first off. After using the the Rejuvenation setting, you can then go back to the clean and balance for a final " clean up".
Succesfull reactivation operations will take time and patience, in my experience 10 mins or so to get it right. Many tubes had excellent emission after this.
Please follow the correct procedure though!
Good to know. So how long did you hit the button to zap the Trinitron in clean & balance mode? There are some rejuvenators specifically designed for newer CRTs, such as the Müter BMR 95 and 2005. These automate the procedure, but it also means you're no longer in control. I have both of these, but still haven't tried on them on my 32" flat Trinitron with spent green gun, as the prevailing opinion is that these tubes are easily ruined. This video gives some hope (and the B&K used here is infact considerably older). But as pointed out here in many comments, YMMV.
Had a flashback to my cousin's pc repair shop. He had a commodore monitor for his security cam that was so burnt in, I couldn't tell if it was on or off.
I've seen a windows 95 desktop burnt into a office monitor. Teal background and all.
Was a TV repairman in the 1970’s. Carried a CRT rejuvenator in the van. Very short term fix. Most of the failures of CRT’s especially premature failures was due to poor evacuation of the tube causing premature cathode failure. Rejuvenated many CRT’s, none lasted long enough to make it worth it.
but those were new TVs with early failures. we're talking about sets that have 20 years of operation (and also manufactured with much modern processes). Rejuvenation of "modern" CRTs yields reasonable results. And... what are you gonna do instead? No new tubes to swap. It's either try a rejuvenation, or toss the tube...
Finally a good explanation how CRT rejuvenation works. I'd never heard of this technique until I saw it on Adrian's digital basement channel.
You should check out Shango066 then, he does plenty of work on old CRT TVs.
Awesome vid, takes me back a few years. I still have a rejuvenator, it does not work on LED tv's. LOL
Have you tried? 😂
To be fair you don't need a specialized, high vacuum glass working facility to rebuild a LCD with new backlights. A kitchen table, Phillips screwdriver, and an eBay account will suffice.
We had about four of those monitors in an open rack to show video from our underwater ROV on minesweepers more than 35 years ago!
Hey hello @IBM_Museum! These monitors are the best (ahem, when they have a good tube)!
@@CuriousMarc Check with Sony Japan, there is a good chance you might actually be able to get a spare CRT from them, as those were made for a really long time, and Sony supported them till recently. Perhaps your viewers in Japan might know somebody who works at Sony, and know of a way to send you a NOS or lightly used tube. There probably still are regunners who can fix it as well, though they are all well on the side of grey hair by now.
I still have the Sencore CRT rejuvenator. I used to use it a lot on Cocktail style arcade games - the gun being at the bottom allowed tube debris to fall into the guns and cause H-K shorts which were easily removed. Guns also could be "shocked" and they often worked for far longer than a few hours - months to years. And sometimes it killed them. Its a risk but often no net loss.
I worked a lot in a TV repair shop in the 80s and early 90s and one of the most important rules of the owner of the shop was to never attempt to rejuvenate Trinitron tubes. According to his experience it almost always made things worse.
not true , i had great reslutls
He was wrong
Yes, i agree with the shop owner, trying to rejouvinate a Trini is like flipping a coin. It may work or it will kill the tube. Years ago i killed a KV-1300, so i will never try again that solution on a Sony
@@repairitdontreplaceit How often did you do it and how long did you or your customer use the rejuvenated set? I just remember that Trinitron tubes either die on impact, when you hit them with the rejuvenator, or they work for ten, twenty hours and are then weakening to an unusable state very fast.
correct, trying to rejuvenate a Trinitron is like playing Russian roulette with a bullet in every other chamber.
A trip down memory lane for me! I built my own CRT rejuvenator back in the 70s and it prolonged the life of many CRTs, but others didn't fare as well. A useful tool nonetheless.
I rememenber around 1993 our tv technician did the same procedure on our old philips tv (k12 chassis) and it got vivid colours again. It work, i know!
for a few days.. enough to gain a little time while a new crt was sourced.
Aaah.. Made for servicing. Yes, I agree! I get a nice feeling when I open up an appliance that doesn't require the removal of hundreds of differently sized screws and adhesives to get access to the goods.
Now that is a great result! Tube rejuvenation always amazes me. I hope someday we will find a way to replace the electron gun in our favorite CRTs
Ive always heard from old timers that you should put CRT's on their faces when blasting them with the rejuvenation voltages. Because you're just blasting the carbon off of the emitters, that slow return back to original the original current can be caused by the carbon not being able to completely fall off, and when upright like that, could cause electrical problems if it falls on other guns.
Makes sense. On the other hand i've heard that it can fall onto the shadow mask and wreck havoc there as well. Not easy :D
@@zaprodk yeah as soon as I posted that I got to thinking about how precise trinitrons are for their shadow mask - worth considering!
@@is0p0d That's also why everybody says you can't rejuv a trinitron.
that's literally hogwash.. there is no carbon.. what you are actually doing is bubbling the last little bit of emissive coating to allow the dying dregs to escape.. no carbon..
Interesting!
I SEE THAT HACKERS SHIRT! *(grin)* and one of my favorites too -- the record year. Was good seeing you both and I can't wait until next year.
Anyone else loving the luggable vintage "icky" cam?
I had a degree in computer engineering before getting a job doing data analysis. I've been through the basics of circuit design. I've solved a physics problem or two using nodal analysis. I've played asteroids on lab bench oscilloscopes. I'm over a decade out of practice, but I still enjoy the content.
I think those Sonys have AKB. They produce solid lines in the vertical blanking interval to measure CRT emissions and continually balance the guns. If you under scan you can see it, and it shows up on the scope around 3:30 (the three smaller pulses before the 100% field lines)
In other words, if you haven't tweaked the screen/drive controls and the balance is this far off, it is probably the tube.
Is that true of FD Trinitrons and Wegas? I swear I saw colorful lines when underscanning on my old Sony Kv-27FS120...
These videos are so wonderful. Love the repair of old gear. I hope the tube behaves a little while longer.
Nice job on the rejuv. Now you have time to order a new CRT :) That is really what a rejuvenation or the earlier B&W tube "Brightner" was for. Keep the customer quiet for a week while the new part came in.
Also, nice ITC/Ikegami 730 Eric, not to nitpick put that is not how you hold a p[ortable ENG broadcast camera. It is supposed to be, the camera on the shoulder, the right hand through the strap on the lens with your fingers on the Zoom Servo control, and the left hand used for focusing. At least the Ikegami gives you a shoulder rest, unlike its competitor the RCA TK-76 which just sat the flat metal bottom on your shoulder.
I worked in TV repair back in the CRT era..PIL and Delta's.. used TV's for sale (and rent) in a poor district.. Thee tricks were only to keep the customer happy for the week or so it took to source a replacement new or regunned CRT.. no more than that. They are nothing more (and never intended to be) anything other than a "get you home" temporary fix.
Trinitrons I know from experience don't respond well or last more than a couple of hours. There isn't much emitter on the cathodes and once it's used up that's it.
OMG that takes me back! My dad was a repairman since before I was born and I worked in his shop as a technician. He had a lot of B&K gear (and Sencore too) and had that tester / rejuvenator. I don't think we ever uaed it (or barely so) for the exact reasons you stated. He'd troubleshoot out until he eliminated everything but CRT and then would tell the customer honestly that he could try this but results would be temporary and not guaranteed. Of course that was the days when the recommendation would just be to replace the CRT. And before he retired it would be "buy a new aet" instead of repair.
Incredible! The fact is that trying to rejuvenate a trinitron is virtually impossible, you always end up destroying it permanently. Only Curiousmarc can do that! 😄
Yes it's pretty hard also love your channel
Yes, I came here to post that -- never rejuvenate a Trinitron CRT. Or really anything, except as a last resort on a tube that's nearly dead and was destined for the scrap pile anyway. I see people rejuvenating CRTs that are just a little weak and I'm like *"NOOOO! STOP!!"*
@@vwestlife if it is little weak people can do Clean/balance like i did to my PVM that had a dirty red gun and poor brigthness , now its a perfect tube working like new
not true , i boosted many back in the day . they rejuvenate well if you know what your doing
@@repairitdontreplaceit Can you elaborate, please? What people needs to look out for when rejuving Trinitrons?
I retubed and recapped dozens of these Sony 9 inch back in the mid - late 90s. The tubes were notorious for failing and breaking down. Retubed and recapped they would work for years again, great to work on.
A quick check for me to determine if it's a gun or a driver issue was to cut traces and use a jumper wire to swap a known working channel and gun. Basically drive the green gun with the red driver and the red gun with the green driver.
Flashback to my childhood in the 60’s watching my dad at the kitchen table working on a tv tube with his tube rejuvenator. His tube rejuvenator had a cube with multiple variety of tube sockets on the cube. Was pretty fascinating to watch as a kid.
Bringing back good memories
I've never seen this work. Excited to watch
Eric is a great asset to this channel, and really hope to see more TV-related videos in the future.
My first real job was in a TV repair shop, I was shown the cowboy version of this which was to drive the gun hard and tap the neck of the tube with a wooden screwdriver handle. It was fairly successful and in 3 years I only saw one tube implode.
16:31 Cool to see different moire patterns for the colors through the aperture grille.
Love to see something like that get a second lease of life! I am curious how long it lasts!
Lovely to see a Sony Trinitron - these in various forms were very common in the TV broadcast industry in the late 80s/90s and I remember them very fondly.
That horizontal wire behind the Trinitron screen is something I don't miss about CRT's at all. It's there to keep the phosphors in place; sometimes they make it so thin you hardly notice it, but once you see it, you don't unsee it. And in this cute little monitor it's extra obvious for some reason. Makes you wonder what happened to it.
It's there to keep the aperture grille stable, as it basically just consists of thin steel noodles spanning the entire height of the screen. Not needed on shadow mask tubes, as that's a sheet with holes.
@@hotgluegunguy Yeah and the stabilizer wire(s) (two on tubes larger than about 17") are almost invisible, you'd never see one on a TV tube unless you look very closely and on data displays overall image quality more than made up for it in my opinion. I've taken apart a couple of dead Trinitron tubes and the aperture grill is a piece of sheetmetal spot welded to a heavy frame with slots etched into it from top to bottom, pretty impressive structure.
I would love to know how long it lasts before it goes back to purple
I think it’s reddening already. This is a fun experiment but not a real solution unfortunately.
@@CuriousMarc Would be interesting to let it run for a while and see how fast it degrades and then do a follow up video.
@@CuriousMarc something to note as well, some rejuvenators work better than others
@@Runco990 yeah, same as with GPU reflow, especially when done in a household oven... These things don't last.
Needs to go to Glasslinger to rebuild the CRT xD
I've done this before with a variac and a 4 watt night light bulb at 115v. If you need more voltage you can use the variac to boost the voltage more. You know it's working because the night light bulb will kinda flicker, and it's done when you have a steady glow. If it doesn't work the bulb will be off.
Fans of the channel should create a drinking game -- take a drink every time Marc says "doodly doo." 😉😂
Excellent stuff with my morning coffee :)
Great job as always!
You guys have all the fun! 👍
Half split troubleshooting method - check the color gun drive at the tube neck pin; if bad move back halfway through the relevant circuitry and check; if good at the color gun pin - bad color gun - no further troubleshooting needed.
My wife has a 13" Trinitron TV from about 1980 that she still watches several hours every day, as she has done for decades. Still has a nice bright picture too. She has had numerous offers of larger modern sets, which she always declines. When TV went digital in 2009 we got a government-subsidized digital-to-analog converter so she could keep watching the Sony. Later the tuner gave out so I switched it to the 3xRCA video/audio feeds from the converter. Then the sound gave out so I routed that through the stereo. So now it is just a dumb monitor but she still prefers it to anything else. It doesn't respond to the remote anymore but fortunately there are on-set buttons for the only 2 functions she needs: On/Off and TV/Video. Several months ago it looked like it finally gave up the ghost, but I took it apart and spotted a tiny almost imperceptibly swollen capacitor and replaced that, now it is still chugging along. At this rate it's going to outlive us both.
Cool view of the arcing.
I worked with an old guy in the electronic cage at the Salvation army donation processing facility who had one of the rejuvenators, We had a lot of Sony Trinitron TV's that we hit with it. Yes, you overheat the filaments a little and then zap it with a HF signal to knock the contamination off and it worked pretty good. The main problem most of the time was a red slur coming off the side of an image edge such as a white shirt showed the most.
Ive heard that rejuvenation of trinitrons are very hit or miss, sometimes it works, sometimes it burns the cathode up instantly. So im glad that yours had some success.
Yep, i killed the blue gun of a 1972 Sony...
Interesting and fun video. Thanks!
love your work!
Great vid!! My humble thanks
I've watched enough shango to know when a concanoidal plonkle-shplarvenator isn't cinco-triculating within acceptable parameters (i.e. baked)
Ah, yes. But you have you tried adjusting the reciprocating dingle arm to alleviate the negative positronic warble of the lupino nuts? Without doing that, we don't really know if a visibean is actually prefumilated or not and that can severely moderate the output of the turbo encabulator.
Shnarvle McSharlebvarseler, glazed in flavor country
I love how the revujdjvivudijation worked
Fascinating!
Tube boosting! That take me back to the 1970s.
Great video!
Eric's use of the one hand rule is nice to see,
Always have one hand on your back with HV, might save you
I've repaired countless CRT TVs and Monitors over the years! Even successfully rejuvenated a very CRTs too! :)
I remember Adrians digital basement mentioning that rejuvination was mainly used to keep a tube semi-running while waiting For a replacement to arrive
They used to make step-up transformers to boost the voltage op the filaments to get a bit more life out of a crt. They had male and female tube socket connectors on them so they could be easily attached to the crt.
Every other source says you cannot rejuvenate a Trinitron. The green usually fails first.
Winner winner, chicken dinner! Looks way better than before. I wonder how long it'll serve before re-rejuvenation is necessary.
It's not long ago, I got experiences by Meister Jambo (Watch his videos in YT) in trying getting a 1957's b/w tube of my old "Musiktruhe" to run.. he was very careful with his tube-regenerator, but he showed me, why the tube has finished in performance. Seems like you got good luck with the Sony-CRT, it looks very good !
if you don't own a rejuvenator , you can do it using a 230v voltage and feed it to the tube through a 15 W bulb , and vary the filament voltage with a bench power supply. Works very well too. there are schematics laying around on the internet
12v heater voltage is the sweet spot for me. 1 tap with the screwdriver on the electron gun and the rust just falls away like a dust inside.
@@Raz82000 yep but some CRTs have a 6.3V filament. I found out that it flashes the best by increasing and decreasing the filament voltage continuously without allowing the cathode to get too hot. I apply my 230V AC between the cathode(s) and G1. So far the tubes I regenerated without dramatic failure during the process haven't decayed through time
That was fun! I wonder how long it will last?
Most of these monitors have been ran into the dirt. I have a similar sony (AC/DC version) that likely has a good tube but the deflection board is baked from sitting in a truck in FL for 15-20+ years...
All yours let me know where to send it, may be able to swap tubes or fix the dead baked electronics.
His contact details are in the channel description, so easy enough.
When half of a video you hope its not a tube and then realize the horrors
I wish you could still buy replacment tubes, there has to be some use for them somewhere, not sure if trinitron would still be a trinitron with a diferent tube, not sure are Sony trinitrons so good because they use custom tubes or what?
BTW: thanks for showing what happens to the tube when its rejuvenating
You are the first that actualy showed that, I guess for old folks this was so common that nobody bothers to show it and we always see rejuvination from the tools perspective
Keep us informed please !...cheers.
It can be done with series bulbs in heater chain and a 15w emission bulb ... Is applying ruff dc to the cathode. It shacks the dirt off the cathode. .. I hope u can follow my idea. ... I done mni a delta gun tube and pil Sony Trinitron will go. I did early sets from the 1970s with good success. Good luck guys
use to rejuvenate lots of color tv picture tubes (and black and white) with a B&K 466. it was always a short term fix and could make it worse. it did this by suposidly blowing some of the cathode meterial off to expose fresh cathode over done it was the end of the tube. they also made boosters that increased the filimant voltage
While running the tube tester for emissions - I kept saying "BAKED" - shango approved
You could still use it to watch pink panther
Excellent fix, maybe in the future you can report if the fix was permanent or temporary?
Retro snake oil which actually works wow!
@2:22 Funny when you point right to left and say "R G B" and then point left to right and say "or B G R". It's kind of the same thing 😁
One should not expect the outputs of the red green and blue amps to be the same level because the three different color phosphors on the screen have different efficiencies
Haven't seen one of those tester/rejuvenators in years. Mine was a different model and designed for colour but they are basically the same really.
Trinitron tubes were always a gamble. I never really understood exactly why, but it was always a hit or miss proposition.
Nice to see you got decent results. Now the big question is; how long?
Loved the video.
This is like the electronic version of "blowing out the carbon".
I noticed the camera was branded Ikegami. They were also the company hired by Nintendo to make their first Donkey Kong arcade game. Until Nintendo learned the trick and copied Ikegami's work for Donkey Kong Jr leading to the first court cases about copyright for computer code.
ブラウン管の裏を少し軽く叩いてみると色が変わるはずなのでブラウン管内部の電極タッチとわかりました。😅ブラウン管回路基板やネックソケットではなかったのです。
It's not snake oil, on a tube with a decent sized lump of cathode it can yield a good amount of extra life, even into the years range, unfortunately the Trinitron tubes don't fall into that category but you can often recover them and get some useful extra life but it's not a given and you have to be careful with the current.
Later B&K tube rejuvenators are a *lot* better at controlling the current, you can start off with a very low setting and crank it up if you get no extra emission.
The other trick you can do to gain a llittle extra emission is to raise the heater filament voltage (if it's derived from an open frame LOPTX then you can open circuit one end of the heater winding and run an extra turn or two of wire in series) and run the tube hotter for a few hours after a gentle rejuvenation
Magic!
From this channel I'm expecting a video where you open the tube, repair the filament, and then pull a new vacuum and seal it up 🤣🤣
Finally we can play Melee on that thing!
Tricks for soft CRT's. BTW consumer Sony Trinitrons WILL NOT rejuve. Only last a day at best !!
1) jump out the series filament resistor. Use scope to be sure its < apx 8 V.
2) if the FBT has an open core add a winding or two to the filament. Again check with scope.
That will get things usable for a while.
Oh and get a newer CRT tester that is not brute force !
LFOD !
Amazing 😄🙏
The best rejuvenator for the Trinitron tubes is the Sencore CR7000. It uses a very light 1 ma setting for the Trinitron tubes.
There is a same trick for VFDs (which are basically flat CRTs with shaped phosphors in form of segments and digits) but it doesn't last long too.
wow! very cool! wonder how it will hold up over time!
The later BK rejuvenators used a better, more gradual method than just blasting a hole through the cathode.
The only possible replacement for CRTs with comparable display characteristics that I can think of would be something done with lasers, mirror wheels (not mirror servos for X-Y as in laser projectors) for vertical and horizontal and some optics for adjusments.
If I had the engineering knowhow and money I would even try my hand at it myself.
Being that my main interest in this would be compatiblity with old and not so old computers and games, I'd aim for something that could do from 15kHz to 31kHz at least, perhaps a little more for systems at the edge of the HD era, and some PC style video modes, maybe.
The problem is that a CRT works because of the phosphor persistence. If you scan a video raster on a white surface with a laser it will flicker too much.
There might be a way if you had RGB fluorescent stripes on your wall and modulated a UV laser that had the RGB signals sequentially activated and synchronised with the stripes. You would need to use optical feedback to maintain lock.
@@KallePihlajasaari I don't think that the on-screen phosphor persistence plays a big of a role at all. From what I've seen, that's seems to be more of a urban legend than technical fact. Maybe in earlier phosphor formulations, but not on later ones.
Have you seen the high speed footage of a CRT that The Slow Mo Guys released a while ago? youtube / 3BJU2drrtCM
The glow barely lasts for a few lines, and at much diminished brightness. I think the persistence phenomenon is just an effect of the human visual system.
If phosphor persistence was so strong as to keep any significant light emission on screen for long, I don't think classical scanline based light-guns for shooting games (like the namco GunCon) would be able to work at all, since the photodiode in the gun is focused to pick up a pulse from the screen and compare the timing it to a diverted composite signal also coming into it's circuitry in order to calculate the aim very accurately. down to a small fraction of a line. If the screen stayed bright for a long time, it would be impossible to tell the difference between the passing beam and it's tail.
There was also an old video from some guys, I think from Germany, that had made a similar display with laser and mirrors, but, in this case, it was with a pivoting mirror, so the scanline would travel back and fort on alternate signals, which is, of course, incompatible with the type of signals (and lightguns) I would want this for, defeating the purpose completely.
I'm trying to find it.
In short, I don't think scanning a bright enough laser point across the screen would produce more flicker than a the phosphors of a CRT lit by a scanning electron beam.
EDIT: Come to think of it, even regular XY pivoting mirror laser show projectors don't flicker that much in person. Persistence of vision is much higher than phosphor persistence.
Oh, and I didn't mean this as a wall projector. My prefered setup would still be a selfcontained unit, something similar to the old retro projection TVs with three monochromatic CRTs for red green and blue. Hopefuly smaller :-)
EDIT2: Come to think of it, again, even with chearp laser pointer you can just doodle lines on a wall and see a pretty long trail thanks to persisistence of vision. You think your hand can move that thing faster than a mirror wheel? ;-)
EDIT3: I found the german laser projector again: youtube / meMM69if74s -- hackaday (dot) com /2011/12/31/full-color-laser-tv/
It does basically what I would like to do, but in a different form factor, and maybe with collected led light, instead of proper lasers.
For some reason I thought it was based on pivoting mirrors, but it seems that at least the horizontal scanning is done with a mirror wheel, as I want to do too.
Out of curiosity. Would you know of a good material for retroprojection with a great black level?
@@radornkeldam You are correct. Eye persistence needs a bright field about 20 times per second, dim images rather more often. With the persistence of the TV screen phosphors they could get away with less brightness.
It looks like the technology is maturing and soon to be available as hackable devices I expect.
I found the following DIY rotating mirror project video on YT
L4zR8qrH8Vc
And the following compact version that uses a dual axis steering mirror.
ET7jP2OsxzA and just before 5 minutes.
This video has another similar pico laser projector engine tear-down from 12 minutes
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For back projection they used diffusers with a lenticular lens screen behind it, not sure why. Like on any back illuminated display, adding a neutral density filter in front increases contrast (ambient light passes through the filter twice) but decreases brightness so it is a trade-off unless you have a high power light source. For front projection there are companies that make the theatre screens but they are white and have a reflective surface and rely on a dark theatre.
@@KallePihlajasaari That first rotating mirror project uses a pivoting mirror for vertical scanning, which means it scans one frame or field downwards and the next one upwards, and that wouldn't cut it for replicating a CRT which always scans in the same direction. Also, the horizontal scan rotating mirror has only 4 faces, so to achieve the bare minimum horizontal refresh of 15625Hz for PAL and ~15750Hz for NTSC (technically about 15734,xxx in pure NTSC, but consoles never match these exact timings, PAL or NTSC), that mirror would have to spin at almost 4000 rps, or 240000 rpm ! Even if you coud to it, that would be too noisy, consume too much, and die early.
The German project I linked seems to use a ~36 face mirror for horizontal, so about 440 per second or 26250rpm, which is way more reasonable, but, in my opinion, still too high. For vertical, I think they still use a pivoting mirror too, so not good for my CRT replication goal.
For reasonable performance, the mirror wheel would have to have of between 200 and 400 faces (perhaps 300, as a middle ground), and have a relatively big radius, and, to widen the angle of deflection into the vertical deflection mirror, a lens would probably have to be used. My goal, as I said, would be a self contained unit, not unlike a classic CRT set, not an external projector, so measures would have to be taken to reduce the projection distance needed.
Anyway, those figures are for Standard Definition 15kHz resolutions (240p60, 480i60, 288p50 576i50)... for Extended Definition (480p60, 960i60, 576p50, 1152i50), double that... Man, calculating these numbers makes me lose confidence in this idea...
I'll need to further investigate rotating mirrors to see how many faces you can reasonably have on them, sizes, speed, vibration, energy consumption... It's getting complicated.
Basically, I need as many faces as possible on the horizontal deflection mirror wheel to reduce its rotational speed.
The veritical deflection mirror is not a problem, just having to do 50 to 60 Hz. Even a 4 side mirror would be under 1000rpm which doesn't sound problematic at all.
Anyway, the problem with the other projectors you linked is that they are all based on pivoting mirror which necessarily scan back and forth up and down, and that doesn't work directly with classic video signals. This is a good technique for using pivoting mirrors, given their characteristics, but it's not how analog TV signals work, and that's what I want to recreate, as my aim is direct compatiblity with old game consoles and tv computers, and even CRT scanline based pointing devices, specifically lightguns.
Pivoting mirror designs, no matter how good their results in terms of visual quality, break compatibility with that, and, thus, aren't what I'm looking for.
Even if I ditched lightgun compatibility, I'd need to add a lot of signal processing, including buffering of frames, because the frames would be coming in sequentially, top to bottom, left to right, and, on alternate frames, the laser would scan "backwards", so the incoming signal could not be fed straigth into it, but would have to be stored into a framebuffer and THEN displayed. This would add at best, a delay of 1 screen refresh, perhaps 2.
If I'm ever going through the trouble of making this, my aim 100% CRT behavior recreation. Otherwise, it's just another display competing for picture quality, and the market is full of really nice LED flat panels. with tons of features and crazy resolutions.
EDIT: I've been doing some calculations and thinking about the details of this thing, and it's going to be more complex (and expensive) than I initially thought.
Even to support EDTV resolutions (480p/576p), the horizontal refresh is almost the same as 1080i60 (720p is higher still, and 1080p is a nightmare).
I thought of a possible way to pack two lines for each mirror face, but that involves complex lenses... but so does mere geometry linearity, so I don't know...
@@radornkeldam There was a scanning IR vision system that used 8 parallel sensors that was used to scan with a polygonal mirror where each mirror was slightly tilted. The back of the mirror was used to scan 8 LEDs into the ocular. The 8 facets would scan one 8th of the field every revolution with 8 zones in parallel. Not suitable for your application but might offer some ideas.
One idea might be to bounce the light off the polygonal mirror twice to get double the deflection angle. You need to have similar number of facets on the drums to get similar aspect ratios otherwise.
Green always run the hardest, because it is the one with the most use on a typical screen.
Does this mean that Marc had, for a while, a Binatron?
In the past I've seen a Beltron device do its thing. I've always wondered how it worked
Sad to say but after seeing many screens die over the years that filament is on it's last legs too, by the end of the video it had that sickly blurry look to it. It will look fine when you turn it on but be unusable in 10-30 minutes when the tube heats up, then they just go black.
If it was just the gun issue though it may have worked. Perhaps failing filaments can affect a guns performance, that maybe being the first indicator the filament is on the way out.
Upgrade filament supply to 5V and it will get a boost of life again, though if you are careful, and slowly, as in over 5 minutes, take it to 7VAC using a variac, you might get a good amount of extra life from it by having the oxide layers churn over to reveal fresh oxide. Last gasp though, good chance of blowing one of them open this way.
I have one like this in pristine condition
if it was an old vacuum tube set id send you over to Bob Anderson's channel
Usually 6.3 filament voltage
I love the Stayin' Alive @100 bpm! Hahaha
They are very reliable monitors. I used them every day for years and never had a problem, though every week I had to do a line up of the picture as the monitors were on trolleys so they shifted.
Cool beans fellas....
Да, было время... сколько я в 90 годы таким способом "восстановил" кинескопов!