Hogan's Alley PPU not working

[unripefruit]

Hi all, first post.

I recently purchased a Vs. Unisystem and have since been furiously buying, trading and swapping out chips, boards, daughter cards, toppers, and all that good stuff.

Unfortunately, amidst all the commotion, I fear I may have broken my Hogan's alley PPU.

When I connect the PCB and turn on the machine, I get a black screen. No colors, no flashing. When I swap out the PPU for, say, the Duck Hunt PPU, the game works fine (although with wrong colors).

Previous to this, I was using the Hogan's alley PPU in my Vs TKO Boxing daughter card because it was missing its PPU (again, wrong colors, but at least I could play it). So I know the chip was working as recently as last week.

TL;DR: my Hogan's alley PCB gives me a black screen. When I swap out the PPU, the game works. Does this mean the PPU is fried or could there be another explanation (bad pin connection, etc.)?

[Joe3693]

It might be a bad pin, look it over closely. Otherwise it sure sounds like a bad ppu.

[unripefruit]

Thanks for the reply Joe. The pins all look fine, so I think the PPU may have died.

I'd really like to avoid having this happen again. What are some common mistakes people make that lead to PPUs dying out of the blue like this? I read one post where someone said putting a PPU in backwards can fry it. I may have done this by mistake but I can't be sure.

[Joe3693]

Yes putting them in backwards will make them stop working. I did that once when i wasnt paying attention. Now i check them like 3-4 times when i install them before i turn the game on.

Thats really about all that kills them. I guess maybe a bad pcb could, or a power surge in the whole system maybe, but that would likely fry out other things before the ppu

[unripefruit]

That must be what I did. Darnit. Expensive mistake. I assume there's no way to fix them once this has happened? I'm sure I'll be just as paranoid as you going forward 

[John's Arcade]

Those boards are finnicky. I'd try the PPU in another board to make sure.