Playchoice 10 scrambled graphics

So, I bought a Playchoice 10 a while back, and the damn motherboard is really messed up. Has graphics like the old NES days where you had to blow into the cartridge to fix it. Yes, I wish it were that simple.

Here's what I know it's not. Ready?

Z80
CPU
PPU
ROMS/RAM
Games (I have 6 games, all with the same issues)
slots
edge connectors
voltage

It's NONE OF THESE. I've systematically eliminated all of these all over the last few weeks of banging my head against the wall. Ordered new roms, tried multiple connections. Changed voltage from low to high and everywhere between. Tried all slots, all games in all combinations. Put in a new CPU, new PPU (from a working board as a test).... and Z80 controls the menu screen, which works great. It's only when you go into the game you get the messed up graphics.

What, in the name of sweet sweet Jesus, is left? I cannot see any broken traces. I've gone over the board, for hours, with my multimeter checking continuity on the board. What else is left??? I really don't want to buy a new mother board, as I've determined that just about the entire damn thing works perfect.... there's just that one needle in the haystack that's fucking everything up.

check the harnesses.

edit: I know you said you checked the ROMs but double check the PCHU-21-46, PCHU-21-45, PCHU-21-39 and PCHU-21-38

If there are any socketed chips try reseating them on the main board. Also if any surface mount chips give them a tap while it's on to see if anything changes.

As for socketed chips, not only did I reseat them, but I checked for continuity and got NEW ones. I'm just doomed on this, I guess. Thank you for the help!

TougaKiryuu said:

double check the PCHU-21-46, PCHU-21-45, PCHU-21-39 and PCHU-21-38

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This will show my idiocy on the subject, but I'll be damned if I can't find those on this board. You're not speaking of PCH1-C 8K/M/P/T, are you?

Wow you've tried everything I can think of.. Did you know of this condition pre-purchase? Also, have you tried whispering sweet nothings in the board's general direction?

Spike Spegel said:

This will show my idiocy on the subject, but I'll be damned if I can't find those on this board. You're not speaking of PCH1-C 8K/M/P/T, are you?

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Nope. Those are the main ROMs. Look for 7N/Q/D/E 8B/C/F/H and 5Q.

edit: i labeled em as the part # lol.

Only thing I can think of off the top of my head...are all the pins in the main connector to the board compromised in any way; either loose pins within the connector or wires connected to it? Not too overly familiar with an arcade PC-10 set-up but I remember having a similar issue with a JAMMA connector doing the same thing to a game board, no matter which one I put in. The board itself could be the issue however you did put new chips in so perhaps compromised traces on the back side of the board could be causing it.

Spike Spegel said:

like the old NES days where you had to blow into the cartridge to fix it.

Click to expand...

...good times.

Bad cart sockets/pins... corroded chip sockets... damaged chip sockets... gouged traces on the board...

Beyond that, you are stuck troubleshooting TTL logic chips with a logic probe.

Sorry to revive this old thread, but Spike - Did you ever figure out your problem? I'm having similar issues with my PC-10.

I finally fixed it by throwing it away and buying a new one.

I worked on that thing forever, and never ever found the issue. Too bad.