Pentranic CH-288 CGA chassis Vertical deflection problem

[kyle1111]

Hi Guys, I'm having a vertical deflection problem with a pentranic cga only chassis.  At first I was getting just a straight horizontal line across the screen.  I checked all electrolytic caps and changed out any with high ESR readings.  It did nothing to fix the problem.

I then tried changing out IC3(AN5521), which again did not fix the problem.  I investigated further and and found R336 and D401 to both be bad, so I replaced them.  I was then getting an image that was about half the height it should be and distorted, very similar to ARM123 post on his 1432 chassis (Re: Pentranic 1432 display issues [UPDATE]).  It was very similar to his picture but without white bar in the center.  I smelled something burning and shut off the monitor before I could get a pic.  It turned out to be R336 (4.3 ohm) again.

I'm guessing either I have to change out IC3 again, as when I put it in both R336 and D401 were bad. Or maybe the flyback is bad and needs to be replaced.

An suggestions would be greatly appreciated.

[kyle1111]

Well I fixed it!  I replaced R336 again and IC3 which I stole off a project chassis I bought off ebay turned it on and it works fine.

[grantspain]

well done,sounds like the ic Vcc was going to high and blowing the chip