Randy as an arcade hobbyist and techie, I really appreciate this seminar and explanation of how monitors work. Your right that a lot of ppl just want the game to work but along with the classic PCB repair monitor chassis repair and maintenance is just as important.
Man, you are a god send. I was starting to think that learning how to work on CRTs was a lost cause with the lack of accessible information on the subject. This is brilliant.
Well Done Randy! When I was in tech school, I lost my perfect 4.0 GPA because I broke the neck off a live picture tube in class while it was on and running. The stupid ass service manual said to remove a jumper off the main analog board. It was stuck, so I used pliers. I pulled too hard and when it broke loose, the moment of my hand, pilers, and jumper smashed into the neck of the screen. I thought for sure I was gonna die. But the truth is, when you break at CRT, while yes is sucks a lot of air into the vacuum, it does not implode/explode shooting phosphor-coated poisonous glass shards all over the place. That being said, don't recommend it! LOL I think the most common myth you busted is that the high voltage sucks the electronics onto the screen. I think even my college instructor told us that's how it worked. Your the first person who got it right!
Thank you so much for sharing these! I actually started by stumbling across #13 on ground and definitely need to work my way through all of them! Hoping to keep growing my skillset to keep my arcade games and CRTs living for as long as I can muster. Definitely spend more time working on them than playing at this point =P You're an absolute treasure, thanks for sharing your knowledge!
Man your really good at teaching. Wish I would had came across this before I got rid of my last 5 Arcades.. Who knows I think I may pick it back up now.
I also found your lecture very useful esp on the topic of "G2" or "screen grid'. The two most challenging CRT based things I have ever worked on were the very first true flat-screen CRT monitors made by Zenith. They were VGA computer monitors. Convergence was a total F*****G B***H!!! all analog pot and coil adjustments, and every one of them affected every other one's result. It was like chasing your tail. It took me hours upon hours of screwing around with it to get it even close to the factory perfect settings. And F**K those purity rings at the neck, if you ever even fart next to those, just toss the CRT in the trash, I have NO CLUE how anyone on gods green earth could EVER get those set up correctly. Maybe there is some sort of robot/machine or a very specialized tool? All know is if you mess with them, its game over. The other CRT nightmare made the zenith vga monitor look like a nice walk in the park. This was a commercial-grade/military video projector that used 3 CRT's. But they were not R G B, all three where inferred phosphor. The photos they gave off where each collected in a condensing optical lens and focused onto an odd and very rare device called an ILA. This was a crystal, kinda like an LCD, but instead of passing visible light thru it like they do today, it actually just polarized reflected strong beams of R G B visible light. ILA means 'Image Light Amplifier". These strong beams of visible light came from an insanely bright xenon arc lamp. This was broken into its R G B via special optics. The Green beam enters a beam splitter and gets shown onto the green ILA. Anything on its backside of the ILA comes from the infrared CRT. As such, anything that should project out to the screen in the color of green would be polarized. So if green was needed in that part of the raster, then it was polarized. If green was not needed, then it was not polarized. How much polarization determined how much green ended up making it back thru the beam splitter and onto the actual screen. Same for red and for blue. youtube my name "carey treesh" if you wanna learn more about this crazy-ass thing. The end result was pretty sweet tho. True analog 1080p HDTV projection at 6000 lumens, in the early 1980s. But it came as a price of 240v @7000 watts and a price tag of a quarter of a million bucks! plus it needed re-calibrated about every 3 months which could take days.
Hi Randy, thanks for this series! What happened to your earlier 4-part series on CRT monitors from ca. 2010? These were essential viewing for CRT troubleshooting fundamentals. Unfortunately, I never got beyond part 2 due to lack of time. :^\
Hey, Robin. Of course, I know who you are. In fact, I saw Hostess a couple of years ago. He was servicing a homeowner pinball just down the street. "Pinball Housecall" was his business name.
