It must have been at least 25 years since I have looked at trying to repair a CRT computer monitor. Yes, I have restored and repaired many proper CRT televisions to date, but PC monitors have fallen away long time ago.
Having said that, I am starting to get more and more retro gaming enthusiasts bringing me things to repair that takes me back to the 1980s. For me, retro is 1950s, but that is because I am on old fart and should be sent off to a field where I can spend the last few days grumbling about Hunts capdensors.
However, this monitor came in, belonging to a Spanish retro gaming enthusiast. I agreed to have a look.
The monitor wad dead, but was drawing 5 watts from the power, so something was alive. Looking around at the primary side of the power supply, there was a bit of life. It was trying to start but was shutting down in protection mode. Checking all the components in the primary side of the power supply, told me nothing nasty was going on there. The secondary side of the switch mode transformer was very shunted, so I suspected short circuits somewhere. Something I cannot explain, after much testing, 3 diodes were found to be short circuit. These fed various low voltages to the signals section of the display. All associated components tested good. With all these replaced, the monitor burst into life with a lovely EHT crackle. This took me back to my teenage days, repairing TVs in people’s houses.
With a PC connected to the VGA port, the picture was poor, with bad definition. This was so familiar with the old days of valve TV sets. Looking at the board on the CRT base connection, there was an open circuit HT filter capacitor. Once changed, the picture was amazing. I looked from the laptop display to the old monitor image. Do you know what image I preferred??? It was like going back to the 1970s, with GEC and PYE colour TV sets, where the CRT was driven by CDA circuits.
