PC Engine LT "stepped dimming" issue

[futurematt]

Hey folks,

I wonder if anyone can shed some light on a video issue (excuse the pun). It doesn't seem like a standard capacitor failure as you can turn the unit on and it starts up normally, but the screen brightness dims in a stepped manner over the course of 30 seconds (dims about 50% each ten seconds). Audio is fine throughout. However I've noticed the brightness control does nothing. I may have overused the brightness control the last time I played the unit before this happened (couldn't find the right level for the light conditions I was playing in). Could the capacitor in this control have gone from all my waggling?

If I power it off at this point, then restart immediately, it's like the signal isn't syncing to the LCD screen, wavy green flickery lines. But if I leave the unit, and restart after a minute or so, it goes back to being bright for a few seconds, and repeating the stepped dimness thing.

It has had a problem free existence (video / sound / power) ever since coming into my careful ownership 7 years ago. No cap replacement that I know of.

Very grateful for any advice. I've seen the capacitor replacement chart and noted another user had a fault in the brightness potentiometer.

Thanks


 

[Keith Courage]

was there any capacitor leakage before you changed them? If so, take a look around the board and try to find if any connections that might look corroded. I've seen this happen on turbo Express units where if the leakage isn't too bad then typically you can get by with just re-soldering the connections on these parts.

[futurematt]

Thanks for the reply Keith  :idea: I'll take a look!