Distortion on My Pacman Cabaret

[wemr97dl]

The monitor is  G07FBO
I had the monitor repaired and got it back, the original problem was Verticasl Collapse? Just a thin Vertical Line.
The colors look great now, but the screen is slightly pulled down on the right side of the screen? Can this be adjusted out??

[lilshawn]

this is just a horizontal timing issue. (monitor is turned 90 degrees, so an up and down direction is actually left and right as the monitor scans the lines) maybe a cap, maybe a dirty adjustment pot. noise in the power supply. hard to really say without knowing exactly which monitor is in that cabaret.

timing is basically waiting for a capacitor to charge from a power supply... whose level and durations is adjusted by a potentiometer. a capacitor will charge at a set rate... 0 being the start and charging up to whatever, say 20 volts) would be the end of the scan line. as a result, allowing more voltage would charge the capacitor faster to that 20 volts before being reset. the scanline gets longer and your picture width reduces.

this is of course grossly simplified. you could tell where the issue is by looking at like 10 different oscilloscope traces the makers of the monitor... from all over the board... and every one of them influences the final power supply feed rate for that timing thing I mentioned above.

but easy things to check is how old the caps are and if they might have actually been changed previously...they may have skipped a few ( if it WAS done....or whatever.)

and just cycling or cleaning the pot controls responsible for the horizontal timing size/hold/etc

[wemr97dl]

thanks for the detailed explanation,
I did have the monitor recapped, maybe a poor job or they did skip a few, after its on for awhile it almost goes away though, it'll have to do for now till I have time to look at the board myself or get it to someone else
thanks again.

[lilshawn]

i mean skipping some is not necessarily a bad thing. typically the electrolytics that are like 100uf and up should all get replaced, and anything high voltage should all get replaced. the low uf caps i hardly bother with since their operation is usually inconsequential. (light local filtering and whatnot) changing a cap for the sake of a fraction of a uF  when the cap is 2.2 to begin with is within tolerance anyway and they don't get stressed enough to drift much anywho. and the ceramic and polymer dipped caps don't change much at all, and if they fail, they usually short out and blow up or catch fire ... so they are pretty obvious when they need replacing.

try maybe giving the horizontal hold a tweak and see if it straightens out.

[Zebidee]

Use an ESR meter to quickly go over the electrolytics. Failing electrolytic caps will almost always have high ESR.