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Re: Quandchrome EGA screen failure.

in Marvin \ Video
Thanks for the heads up on that issue too. Its really appreciated. I have gotten a Blue ESR meter now. Its something I should have gotten earlier, its a fantastic tool. I will check the caps in the monitor when I have time. I might desolder some of the logic chips and test in my ti866II as well, but …

Re: Quandchrome EGA screen failure.

in Marvin \ Video
Thank you for the good explanation, I will try to stick to the original part-numbers then, maybe 54 series instead of 74. If I find any optoisolator chips I might as well just change them. I am a bit afraid of any adjustment work needed after changing a lot of components in this monitor tough. There …

Re: Quandchrome EGA screen failure.

in Marvin \ Video
You do not think the 8V have burnt the chips on the board? BTW what makes the power supply give that high of a voltage to begin with? If a 74-series logic chip is powered from a certain output on the power supply, that output is supposed to be 5V. If that output rises to 8V, that chip is likely …

Re: Quandchrome EGA screen failure.

in Marvin \ Video
I looked for the horizontal deflection circuit, I think i found it, but i dont know much about these things. The circuit looks good. But the coil has some corrosion on its grounding, i dont know if its so much that it matters somehow tough. Since none of the TV-repair shops around answers my call, I …

Re: Quandchrome EGA screen failure.

in Marvin \ Video
On the video input circuitry there seem to be a SN74522 chip that has been changed. As the board looks to be heated on the back, and possible flux residue. Or is it fried? Edit: I disconnected the input circuitry and turned on the monitor, its just as black and dead as when the EGA card is connected …

Re: Quandchrome EGA screen failure.

in Marvin \ Video
I finally opened up the power supply. It seems there is a load resistor on this monitor as there was no charge on the tube at least. The power supply looks as if it went of the production line not long ago to me. No caps are bulging, except the two big ones, but i guess they are supposed to be like …

Re: Quandchrome EGA screen failure.

in Marvin \ Video
I think I will open the PSU then, hopefully the fault is obvious, like a blown capacitor or something. And if the board marks what voltage the different points should have I can check them, but otherwise I have no idea. I have had no luck finding any schematics on this. Its hard to find any info at …

Re: Quandchrome EGA screen failure.

in Marvin \ Video
Thanks for the replies guys. I have not had the screen on for much time of course. but I did need to see if it worked and if i could get it to work in CGA and so on. I have tried two retro\TV reps locally but none answers... You do not believe in going over the power supply?

Quandchrome EGA screen failure.

in Marvin \ Video
I have gotten a Quadchrome EGA screen. I plan on using it with my IBM 5162 with a CHIPS based EGA card and that is what i have tested with. Ufortunatly the screen wont work. Initially I got it to display some scrambled red text when CGA was selected on the video card. But now it goes completely dark …

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