Hello all - I'm throwing up the tech batsignal on this Display Driver board - hoping someone can point me in the right direction.

So, just to fill in the backstory - a client I'm working with bought a Stern 520-5055-00 REV-E display driver board off eBay used to put in a reimport game that was gutted (JP:Lost World). He then ordered a ROM chip for it and installed it.

I'd previously noted the HV board wasn't putting out the required voltages in a prior call, so he ordered and installed a new one. Unfortunately, no display still. I went back through the system and verified all of the voltages are there, and was just about to swap the board for another one from his South Park to test, when I noticed the ROM chip was installed upside down. I tried to flip it, but the damage to the chip is already done and it's roasted.

First question - That's obviously going to destroy the chip, but could that have damaged anything else? (I didn't think so, but wanted to confirm. Only encountered a flipped ROM one other time, and it didn't affect the board. However it was also a Gottlieb Sys3 Sound board.) Luckily, I have a ROM burner, so burning him a new one is easy.

Anyway - So I removed the ROM and the board. We tried the board in his South Park and while we did get an output, it was very garbled. It was getting late, so we decided the next best step was for me to take the board home and do some additional testing (I have a VND, so I can run it in my game). When we were packing up for the night, I swear I saw/heard a spark on the board, but I'm not 100% sure. It looked like the 40-Pin Processor, so I kept that in mind should anything else pop up in my testing.

However, when I got it home and installed it in my VND - the board immediately blows my 5v fuse which of course bricks the game. I replaced the 40 Pin as a precaution due to the phantom spark, but still am blowing the 5v. If I check continuity, I'm getting a buzz between the ground and 5+ line on the connector coming in which seems to indicate a dead short.

Second question - Any ideas where to begin troubleshooting next? I don't see anything obvious (no burns, no marks, the board looks clean and untouched other than my 40-pin replacement.

Thank you all for any assistance!

Truthfully - I have no idea. My client bought the board and put the ROM in himself before I got involved. Neither of us have seen it working in a game. I did try it briefly in his South Park (had output, but it was garbled). That was after the upside down ROM chip (which again, I wouldn't expect lasting damage from, but wanted to ask the question). This was before we packed up, which is why I keep wondering if there was a shock as when we had it in lost world and South Park, neither blew the 5v at that time.

So I have the board right now, and with a confirmed working Viper Display ROM in the correct position, hooked up correctly, in a confirmed working machine - the 5v fuse blows and obviously stops the machine from booting. I took the board out and did some testing... I found that if you put leads on the two power pins (5v and ground) I show continuity, which I believe is seriously incorrect.

Yes, the board was powered up a number of times with the ROM upside down. I know this will fry the chip, just unsure if there is any effect to the board long term. I've burned a replacement, but haven't installed it (since I'm testing at my house with my Viper)

Here is a close up for reference on the ROM Location (apologies, not at home this minute and the only pic I have) - but putting the ROM in is straightforward - only one position has the socket, and matching the notch for it.

20190321_232329 (resized).jpg

That's why I took it home with me... Tried it with a working VND ROM/machine and it pops the fuse.

That's the only way I know how to handle it too. That's why I figured it would be better to at least post something and see if the Pinside hive mind could come up with a better solution than the full on shotgun approach.

I could test a number of the components, but there is still the risk of getting a poor reading with them in circuit. If someone said 'hey, it's likely one of these three parts', no problem... But, especially with the surface mounting, a true shotgun approach could literally take hours (depending how lucky I get on picking the correct component).