PC Duo no video, multicolored screen, several problems?

[NichlasEk]

Hi!

Got a cheap duo from yahoo japan. Its in a sorry state.
There where missing caps all over the board. I replaced them and got nothing but a light color of a different kind each time i powered on. So away i went with the multimeter but to no avail. I took a known working 6280 from a pc engine and tried that. Same syptom. swapped out the 6270, same thing. Swapped both ram chips next to the 6270. No luck.

My guess is a broken trace or two, but where to look?
I have started with the logic probe but im not a pro with it.


The 6280 had a realy faded logo as if it was exposed to a lot of heat some time. Some of the pads for it was already damaged. So i guess this could be the culprit. but i get continuity on all traces i have messured.

THe HuCard slot is bent, looks like someone has gone wild on it with a soldering iron. Cards still fits tho (and no shorts). The components under the HuCslot has been messed with. One resistor is soldered upside down, why?

I also tried removing IC520, but no luck.

Thoughts?

/Nichlas

[Keith Courage]

are both 7805 voltage regulators in working condition?

[NichlasEk]

Should have checked that. Now ihave... and there fine. Ruffley 5v on each.
Thanks tho could have been it. Gonna look for small shorts when i have a moment to sit.

[thesteve]

multi color like that is almost always a missing connection to the card or a short between pins

[NichlasEk]

Well i cant find any shorts on the connector. Iv traced all the pins to there via/chip. Guess it could be a bad via. Finding bad vias is teadius work. The plastic on the cardreader is slightly warped. And it seems as if some other components has suffered from more heat than necessery.

Lets say a cap was so bad it had failed open, could that cause a no starter? Or would it just cause random issues?

The hunt continues!

Thanks for the input.