Trying to recover a Failed PCEngine GT recap

[mamejay]

Hey everyone, I have been given a PC Engine GT to complete a failed recap.  Only 2 caps had been attempted and both had pads ripped off.  I have replaced all caps now and traced the bad traces and made sure the caps are in place.

I now get perfect sound but only backlite black screen. I checked the 4.7uf cap was installed correct and it was.  I did notice a missing resistor which I have a picture of.  The other 2 resistors next to it are 830ohm so I added one I had laying around but no display.

Any advice on what could have happened ?  Before the first attempt the user mentioned he did have display but very dim.

Thanks

[NightWolve]

You mean there are only 2 new capacitors and you're asking why there's no video/picture ??

It's because all old capacitors are dead, leaky garbage and you need to finish replacing every one, not just the video one...

That's how mine died, had it in a drawer for some 5 years, pulled it out to play Super Star Soldier, and all I got was a black screen.

I came here to PCEFX, thinking I was gonna sell it broken to someone or see what it'd cost to repair, but then I learned about the usual breakdown problem of capacitors, decided to try replacement myself which totally restored it to working operation again for the cost of $11 in exact caps via Digikey.

Anyway, yeah, finish the job, clean the leaked electrolytic fluid as best you can, solder in all new replacements and hope for the best.

[mamejay]

As stated when given to me only 2 had been replaced.  I have completed all of them now.  I have recapped 6 units so far so I am not totally new to this

[NightWolve]

Ah OK, your photo still showed old ones which threw me off.

Well, you're gonna have to check every trace, possibly even the vias, make sure there's continuity as the leak fluid damages them, beyond the damage the previous repair attempt did... If no IC damage occurred maybe there's still a chance to fix it.

You have the info for the missing resistors I take it so nothing to help you there with. Oh, I'd check the other resistors that were noticibly harmed/cooked too, both for having stated resistance value and making contact with traces on both ends.

Anyway, if you can't fix it, don't know how to use logic probes, for this level of difficulty it might be best left to thesteve - when nobody else can repair NEC systems, they ship it to him, including other repair guys.

[Keith Courage]

No resistor goes there. It's supposed to be bare.

[mamejay]

Thanks for that Keith.  The customer is purchasing a AV output kit and screen so going to get rid of the OG screen for good.