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- เผยแพร่เมื่อ 5 ธ.ค. 2023
- Warning: Working inside a CRT can be dangerous. Don't do it unless you know how to be safe.
Back in the mid to late 70s when personal computers were just coming out, there was no such thing as a "computer monitor" yet. Many machines at the time used composite video for their display, and the only monitors an end user might be able to get that was high enough resolution to clearly display text were security camera (CCTV) monitors. This is one such example of a monitor that might have been usd back in the day with an Apple 1 or Apple ][. It was left for dead but can I rescue it?
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This is probably a common fate of many old security monitors, they got driven 24/7 for years and decades until the phosphor was completely degraded.
@@UserUser-zc6fxwooow seriously? I cannot imagine that a crt monitor could run over 4 decades while running it 24/7,i found 20 years already alot for a crt screen being normally used
Property of "International Robomation Intelligence"
Sounds interesting... EDIT: Turns out they made robotic arms and developed a High Res Machine vision system in the 80's.
I found a surprisingly decent amount of information about them in an article from 1987. They might've been a big deal at some point for industrial computer vision and robotics. Of course, it was mixed in to a bunch of results of articles about AI. Pretty neat unit the way it sounded.
The advice I usually give when it comes to adjusting brightness on a display intended to be used routinely is to initially set it to what you find comfortable, wait a day, then drop it just a very tiny bit the next time you go to use it, wait a day, repeat until you feel it's gotten too dark, at which point, turn it back up just ever so slightly and there you go! :B
Great idea! I need to do this with my PC monitors
It's a pl-259 connector, often used in CB and Ham radio antenna connections.
Those connectors look like SO239 sockets. They are paired with PL259 plugs. Still in common use among us radio hams for HF bands (0 - 30MHz). We use BNC connectors for VHF/UHF (144MHz / 440MHz). Although, as far as I know, BNCs can still be used for HF too. Great video as always by the way :-) Thanks.
Thats what I thought too, not sure why they would choose so239 though on a 75ohm as they are generally considered a 50ohm connector and usually paired with 50ohm cable such as RG-8. They are also designed to handle RF power and can handle quite a bit. Doubt the impedance mismatch would make too much of a difference on composite video though I have never tried it.
@@RC-nq7mg The connector has nothing to do with the impedance.
The PL259/SO239 connector is sometimes called a UHF connector. It is common on HF radios but also VHF/UHF mobile and base station radios. BNC connectors are common in VHF/UHF handheld radios. BNC is fairly common for low power and portable (QRP) HF radios like the Icom IC-705.
The cable would of been RG59 or RG6 , which are 75 ohms.
@@cappaculla sorry it can sometimes affect it amp made two version of the same connector one was 50 Ohms the other was 75 home just a slight difference in the center pin diameter and insulation (BNC like a screw connector circa 1985) if connected to a TDR you can see the mismatch it would be more that what you see on a simple connection bump on the screen
Two remarks:
1. If a CRT is a capacitor, isn't swapping it a way of "recapping"? 😉
2. To lock the exporsure on a Sony camera, set ISO to some fixed value and put the camara in manual mode. Now you can set the aperture to adjust the exporsure.
I feel like green is the right color for a monochrome Apple monitor. All the ones I used as a child were green as well.
I also grew up with green. I thought it was terribly modern when amber became a thing in the mid 80's.
The coating on the steel parts that looks a kind of gold colour, its called 'passivated' steel. It's an alternative to zinc galvanising.
Yellow Zinc plating looks very similar too
I was thinking zinc chromate. That tends to give a rainbow sheen to the parts treated that way. And it's pretty good at corrosion resistance without any further treatment. Although your best bet is a corrosion treatment and then a coating or paint for additional protection.
Cadmium coating is yellow as well.
@@jeromethiel4323old car restorers can buy kits of paint/chemicals to reproduce that finish on engine and other steel parts.
@@ericpaul4575 I sure as hell hope they didn't plate consumer gear with cadmium! lmao.
There was a screen tube factory in Austria.
TVs were manufactured there for all European manufacturers. But that's history.
The lack of DC restoration on monochrome TVs was always a distraction. Apparently there were mods out there to improve matters back in the day, as long as it didn't cause issues with PSU/line stage loading.
I also used to have a colour portable with no DC restoration. As you might imagine, this played havoc with saturation levels. I gave that away.
The phrase for a circuit that maintains the overall black level when the image content changes is DC restoration.
Even the orange colored Hitachi logo is cool. I've seen Apple II clones in similar cases that had some variation of "Orange" logo on the case. So the Hitachi logo would of matched LOL. 🍊
Those look like SO239 (female) connectors on the back of the screen. The male is PL259. I'm a ham radio operator and we absolutely use those 2 connectors for our antenna cables. They work really well!!
Wow, it has green transistor inside it!
Coating used on chassis parts is called yellow zinc plating.
The switch on the neck board is for the DC restorer. You'll want that on for computer use so the black level doesn't vary between overall light and dark screens.
Indeed, I saw that after reading the service manual and turning it on allowed that sub brightness to work, so it's definitely on now. Not sure why anyone would ever want that not to be turned on....
@@adriansdigitalbasement2 if you are running video duplication you want to monitor the signal but not terminate it you would let the end of the line terminate the signal at the recording vcr for example mutch like thin ethernet
@@adriansdigitalbasement2 IIRC, the switch was for servicing the set. It's been so long, I can't remember why. Sorry!
I'm struggling today, and this video was the distraction I needed.
International Robomation Intelligence were a company that made robots (mostly of the fixed armature variety) for laboratory use. This monitor would have been used to view e.g. into a hot-box, an isolated area that would be handling hazardous or biotoxic chemicals.
Beautiful monitor project - so nice to see these period appropriate monitors back to good use!
Sync was used in video mixers. I suppose that in security it was used so that the signal would not jump when the camera was changed.The cameras must be syncronized too.
The yellow coating is called zinc chromate or yellow chromate. It's a common coating for various bits of usually fairly inexpensive metal that need some measure of weatherproofing or at least water resistance. Cheap deck screws are a common use, along with steel sheet and the like. I've also seen it on really awful-cheap cast bits of pot metal intended for outdoor use. For whatever reason, it's a fair bit more common these days than galvanized, but I don't know if I'd consider it better -- especially given the quality of what's usually underneath... which, what of it is present, is best spelled with a leading 'k' instead of a 'q' ;3 Eh... it's durable enough for what it usually needs to accomplish, I guess.
Hey Adrian!
Those coax connectors are called PL259/SO239. The PL stands for plug, and SO stands for socket. Otherwise known as the "UHF SOCKET". They are commonly used on amateur radios, even brand new ones you can buy this minute, along with CB radio and Marine radio.
EDIT
Corrected typo. Changed PL239 to PL259. Whoopsie.
Yep, my CB radios had them. I think the plug was PL259.
@@bouldersoundguy Woops yeah, you caught that. PL259 and SO 239. That's what happens when I make comments when tired.
That looks like cadmium plating, assuming that it's steel. It'll only be anodized if it's aluminum.
You cannot plate something with magnesium. Magnesium can be plated however.
The plating on here is most definitely zinc. 🙂
Looks like yellow zinc plating
It is zinc anodized
My local trash is Baked bean cans, old milk cartons and cat food boxes. No monitors.
Thank you for the video!
That looks GREAT on your clone! Man, I'm gonna have to get a Green screened Apple ][ now!
I love that you are testing the CRT on your tester! As for measuring the capacitance I would suggest you test off the aquadag paint for your negative connection. You don't have a dag spring on that tube as far as I can tell so the ears wouldn't be the place to test as far as I know. Still looking forward to some Coleco Adam content!
In days of yore (the 1950's) they sold "CRT brighteners" that increased the filament voltage a volt or so (6.3 volt filaments). While they did work to a certain extent, the picture tube was on its last legs, and it didn't matter much in the end. I had one that was used on a CRT we had in the house as a kid. Of course with using the monitor a long time the phosphor sometimes got burned if (for some reason) you always watched the same thing (a test pattern?). Not so much a problem with broadcast TV, but things like CCTV setups it could be a problem.
Awesome. Love the monitor videos.
Those I believe are PL-259 connectors
Anyone that ever had a CB radio would recognize those connectors.
PL-259s were commonly used for video signals (Composite, and for sync) in Broadcasting back in the olden days. When I first started in 1970, BNCs were becoming common. PL-259 AKA the "UHF" connector.
I think the sockets are SO-239 and the plug is PL-259.
@@PortsmouthHarbourBoats You are correct, I think. I remember working with them quite a bit working on VHF and UHF mobile radios.
The gold plating is an electroplated passive gold zinc. Back in the day it would have been cadmium plated but it's a tad toxic. I sent my Commodore SX-64 chassis off to an electroplating company to get finished in passivated gold zinc. Looks fantastic... but you don't normally see it :-)
12:00 I used an automotive rust converter gel after scraping off as muchof it as I could using a wire brush and then 80 grit sandpaper, then when the gel dried, aluminum color rust spray paint.
Ah the good ol' days of green screen viewing. 🙂 Makes me nostalgic for the days when I played Number Munchers and Jungle Hunt when I was in 2nd grade in the early 80s.
the thing that changes the brightness automatically is called the AGC, automatic gain control
I wonder how difficult and expensive it would be to manufacture CRTs with today's manufacturing technology and material science.
And if the retro crowd would be a feasible target market, I bought a 3d printer so clearly I'm not above wasting money on cool stuff.
That's quite strange, I never seen a PL259/SO239 used for video! CB radios and low freq two-way radios are the first thing that come to mind, not video haha! This is what makes vintage electronics so fun, especially odd-ball units
It seems to be asset tagged so maybe it was specced to intentionally use a weird connector that someone may not just casually have around to prevent it taking a walk home with someone, and it being screw on probably also helped with just things not coming loose. Dunno why they wouldn't use BNC but maybe it was just what was most easily available during production?
it was common for closed circuit TV and still is common radio antenna transmission line
Yeah, it was common on OLD video equipment. When stuff was still reel-to-reel. Before VHS. In my high school, we had a bunch of old monitors and cables that had "UHF" connectors.
Huh, so that old CCTV screen in the garage might be useful for more than just security-cams! Neat.
Those jacks on the back of the monitor are SO-239. They are *very* common on ham gear as the output to the antenna, especially for HF. You can get various types of coax for it, RG-58 etc. The coax is quite thick but it has very good power and signal fidelity. edit: of course, there were like 5 other comments pointing this out. That's what I get for not reading the comments first!
Got a 27MHz CB-radio that uses this kind of connector to the antenna. The radio is 5 months old, so it's still in use today. ;) I think it's called a BNC PL connector, and connects to the RG-58 or PL259 50Ohms coax cable.
@@tostumpen No, it's definitely SO-239/PL-239. BNC is a totally different thing. These are the sort of things you learn when you get your amateur license!
@@AureliusR Ah my bad. I won't be getting that licence.
@@tostumpen Why not? It's easy, and it gives you plenty more bands and power to work with!
@@AureliusR Well, the equipment is way too expensive, and I have no space for the antenna to put up here. But who knows.. Maybe down the road.. 🤷
Damn it, that’s how I started here! A trash picked big screen tv!
Nice monitor.
My father had a very similar monitor in the 80s for his Apple II+. It had the same SO239 connector on the back, but it always had a green phosphor. Sometimes he'd move the TV into the room with the computer so we could see games in color, and then comment about how 80 columns didn't look good.
External sync jack for House Sync. The cameras would need it too. This enabled seamless switching or you could put it into a video-mux for multiple cameras on one screen.
It wouldn't surprise me if the output of that transformer is 24VAC. Security cameras of the day kind of standardized on that power source.
I use a monochrome monitor (actually green screen) for some audio editing and production, colour sets can be a bit too distracting sometimes believe it or not. It also uses less powere than an lcd
Nice find Adrian! and nice video as always!
Unfortunately all those security monitors were very high hour units driven 24/7 so one must not wait much in terms of CRT brightness. A lot of them have permanent burn images on the phosphor from showing always the same picture. Their construction is great though compared to old TVs and early computer monitors, metal casing, chassis etc.
I would like to see though how this vibrant green CRT measures at the CRT tester, what it shows on the meter.
And as another folk commented before me I consider a CRT swap as core recapping of the monitor!
Cheers from Greece, Jim
Great. Another CRT back in operation!. I'm sure this is commented on already but the sockets on the back are called SO239 and use a PL259 plug. These are very common on CB and ham radio HF equipment and up to around 200Mhz. The type used in that monitor will be a 75 ohm impedance type whereas in radio, its usually a 50 ohm type.
The Emission test (same test used in valve testers, or tube testers) drops the heater voltage by a certain amount, around 10% and the resulting drop gives an indication of the cathode emmision or 'goodness'. In a good tube, it should hardly drop at all (less that 5% is probably good).
growing up my folks bought me a apple 2C and it had a 12ich color monitor that was made for apple by Hitachi !
I have a funny Mid 2000s CRT TV in my office and I just went into the settings and verified I wasn't overdriving it thanks to you.
It also has a funny function where there Is a Notepad built into the TV where you can use the number keys like you used to on old cellphones for entry of text. Not sure why they thought people would want to write a note for someone on the TV.
I so rejoiced when I found a 9 inch B/W computer/surveillance cam monitor in the dumpster. But... everything was broken. The power supply was the only thing that worked. Several caps were bad, and when putting the neck board back on for the second time, the CRT just cracked and broke (I didn't use force!). And with another tube and a lab PSU (for current control), well... turns out the flyback is bad as well. So... not only is this worthless, but it also wasted my time (and the industrial 12V PSU isn't worth all that much). Damn. I would have needed that monitor to fix a rare video games console with built-in monochrome CRT (the Philips G7200)... they have very poorly made flybacks that just fly apart.
The term for describing the brightness level changes when the contrast of the image varies is DC restoration. TVs usually skimp on that while monitors take it seriously.
You can't really measure in the pico range for capacitance with long leads like that. All that measured capacitance was probably just in the lead wires.
At 21.40 into the video, you say "don't do this unless you know what you are doing". Just a hint: You had your left hand on the case while you pressed the power switch with your right. Back in the day, I was told "always have one hand in your pocket when work on high voltage kit". With an open mains powered system like that I would never, ever, have two hands in contact with the equipment.
5:19 that looks like a recent Compaq all in one I recently refurbished.
I picked up a new monitor in the black friday deals for £149 and it took me months to save up for it and its my first 1440p monitor and the first thing I did was turn the brightness down to 50%
34:52 Seeing 3 vertical lines in the square is a common misconception. The intention is to see the controls to only see 2 vertical lines. Going left to right, the 1st vertical line is _below_ black, the 2nd line is true black, and the 3rd line is above black. At perfect settings, the 1st and 2nd lines should be identical.
19:33 the sync would be NTSC black burst sync. They may have made a version of this for broadcast. Usually everything in TV in the NTSC days had a black burst sync to make sure everything in the facility was correctly timed to each other.
Also those are UHF connectors. Very common on older security and broadcast monitors. Basically, it’s what BNC replaced.
My first monitor, used with an Exidy Sorcerer, was the 9" version of the Hitachi
I have a collection of oddball CRTs with different phosphor types. One thing I’ve noticed is that there can be a wide variation in voltages within the same tube family depending on the phosphor used. I have 3 different 5BHP# series, a 5BHP1, 5BHP5, and a purple(!) 5BHP32. The P1 and P5 display a nice bright image at 8500 volts, but the P32 won’t even display an image until 12+ KV. I bet that particular tube family requires a higher drive for the white phosphor than the green and that’s why it was decently bright even with the controls at a minimum.
......Nice job, Adrian!! Just to finish off, the old sockets are SO239 sockets, the corresponding plugs are PL259 types, used by Radio Hams for coax... Cheap and plentiful, should you want to be ultra retro/original!!!
The sockets are PL259. Common on CB radios back in the day :)
Those original jacks look to be the same of a standard CB antenna hookup.
Great restoration,but i can imagine thus must be hell to do so🤣
This one is extremely similar to the one i have from Siemens, just with a slightly different case design. The problems i have with it is that the potentiometers at the front don't make good contact in any position anymore
I have a 27 inch Sony Trinitron from 1998. I'm sure it has composite inputs as well as the 75 ohm and cable. Works well. I never use it. I bought it from Circuit City back then and then had a board replaced with warranty. Willing to sell it.
A lot of the corrosion problems may be coffee spilled from sitting cups on top of the monitor during the night.
Great 😊
Not important, but a very short bit of history.
The sockets you disabled, are commonly called PL239, are commonly used on co-ax cables, for transmission and reception in the VHF, band (around150 mhz) range. They were most commonly used in VHF aviation equipment. The BNC to PL239 adapter, was commonly used to adapt to BNC terminated cable, which was more commonly used in UHF radio (Ultra High Frequency , eg., aviation and radar)
The original broadcast range of the 2 through 12 channels on an old TV, were in this VHF range. but they normally used twin lead cables to the antennas, which were much less expensive and sophisticated and had a resistance value of 300 ohms. In the 70s, when cable became the primary method of transmission, we had to use a 300 ohm to 75 ohm adaptor, to connect to the TV set.
Isn't there some Chinese fab that still makes CRTs? I vaguely remember reading about that somewhere...
There's an American company named Thomas Electronics that still makes CRTs, but it's mostly for aviation stuff and what not.
I asked if that chinese fab still made CRTs in a video some weeks ago and they told me it had moved on.
Coat is yellowed zinc.
"Sync" might be a genlock style signal? Analog TV studios needed to synchronize the frames across all sorts of devices so they usually had a "global" sync signal. Maybe it was used in such settings in a different model? Like one of these camera walls in live broadcast control ooms?
20:40 - my car's CB antenna has the same connector, and I have the same BNC converter for the actual rooftop mounted antenna.
Robomation, sounds like something from Futurama.
Funny thing is that these days, there would be absolutely no reason to try replacing an LCD screen, or often, even the backlight of a modernish monitor. You'd just replace the whole thing. We need to appreciate the remaining days we have to do things like CRT swaps. Unless they somehow come back in retro style, CRTs are just going to fade away, literally.
I know it seems silly and wasteful, but for those few who still use and enjoy CRT monitors, it would be nice to have a company which makes 3 or so of the most common sizes, black and white or color, and will customize the mounting tab orientation as needed. Phosphor technology has come a very long way with the LED, so there should absolutely be a way to help the screens last a very long time without the same fading and burn in problems of old CRTs.
Green CRT is very IBM monochrome!
It's also what Apple's monochrome monitors used.
Late 1940's to very early 1950's TVs did not have aquadag coatings and used separate high voltage "doorknob" capacitors. 250-500 pf were common values so your readings were in the ballpark but those long leads did introduce some error.
I don't think any of the regular electromagnetic deflection CRTs had uncoated glass, at least not in the US. Common tubes like the 10BP4 had a conductive coating on the outside but were usually used with a doorknob cap for extra filtering. There were also metal cone CRTs where the entire bell was high voltage and these required external capacitance.
when it comes to the image brightness changing depending on what the tv is showing, i call it a lack of "brightness compensation" but i have no idea if thats actually correct..
That's a really nice picture of you in the videos thumbnail. I hope you like you new job as a content creator you at least look really happy! Br joakim
I wonder changing the CPU, ROM to "ROMXc", also keyboard encoder to a new CPLD one, can save how much power?
Jackpot!
6:27 120v is a pretty nasty jolt indeed.. 240v feels like your arm is being fried, muscle cramp included. Ask me how I know ;-)
As a kid I was zapped by a flyback (not a live one).. Felt about the same as being zapped by the HEI ignition of my car 😵 It does make for good musical skills though 😁
There are a couple of shops that rebuild CRTs.
Great as usual. A question about the discharge wand...how do you know it is working?......ie: accurate results to say the crt is discharged when it is or maybe not?
there is an analog voltage meter on it connected between the ground and the probe leads
That gooldish iricident coating on the steel is cadmium. Not great for the environment and not used these days (at least not in EU, not sure about US).
Nice job! How you are running smart port on an Apple Plus? Tks.
Adrian needs a dim bulb tester to power up old electronics
I'd guess there might be a video level adjustment on that clone motherboard you could use to get it closer to the 80 col output level.
Will Adrian ever get a non tired CRT tube?
Certainly quite a contrast (badum-tish!) between the two CRTs, pretty much tired versus wired seeing how bright the green CRT is versus the original... :P
I have an Apple II CRT to fix. If any capable fixer reads this from the EU, give me a shout
Wonder if there will ever be a source for brand new retro CRTs? If not, the next generation won't be able to refurbish old monitors like this.
Could it be yellow zinc plating? my mechanics had some hinges sent out for plating and they were that color when he got them back.
I gave a curb alert about a Trinitron on the block across from me and someone in the Toronto C64 group reacted and it was gone later. Still don't know what happened to it but my apartment is too small to hoarde parts anymore. I'm trying to downsize.
What powerbank were you using? Any chance of a link?
Back in the 80s we had several mainframe monitors showing the same info that I think took that type of cable, makes sense they were all chained. Yes, well said, an amp has what is called head room, if it's low and you try to push the volume the output signal flattens at it's upper voltage limit instead of amplifying the incoming signal as is, the flattened voltage lacks signalling ups and downs and ends up heating the speaker's coil instead of driving the speaker louder and then will burn out causing a short and requiring a replacement coil. I had to have a 18" sub woofer speaker replaced because of it all, only the huge magnet was salvageable.
Hello, would you mind to link where you got the powerbank from? That is exactly what I am searching for.
The gold metal coating is likely cadmium.
SO239 is the plug and PL239 is the male plug
I see you're using a harbor freight Philips screwdriver 😊. So do I.
Those video input sockets are what is generally known as the "UHF Connector" en.wikipedia.org/wiki/UHF_connector
Ah yes I see -- SO-239 sockets. So old-school! I wonder why they put those on the back of this versus BNC which seemed to have been in widespread use at that point?
@@adriansdigitalbasement2Those connectors were very common in CB and ham radio RG11 coax. BNC would need a thinner gauge of RG59 coaxial cable, and those connectors were probably kept because the cables in the existing installations were all RG11, and moving on to BNC would require all of the installed cable (at least in the video bays) to be replaced.
have you found the washer yet
OK, now I desperately wanna know what was going on inside International Robomation Intelligence!
That corroded gold-rainbow coating appears to be zinc chromate. It would be a good idea to wash hands after handling it. The un-corroded plating is probably not particularly dangerous for occasional exposure, but I am unsure what chromium compounds are present at the actual site of corrosion (any chemists in the audience?). Soluble chromium compounds are generally bad news for living things.
That's the sort of disappointing nature of vintage screen manufacturing, the tremendous lack of AV port types, even though RCA ports date back to the 1930s it seemed to take a long time to establish Composite in all NA screens. The S-Video port launched in 1987 but they could have done it without that DIN using an RCA connection much earlier what with Chroma & Luma lines sitting dormant in so many CRTs.😒