Omega Race PCB repair #2

[ifkz]

Next up, I think these are the DACS. Humm, these have short legs just like the ones on my good set. I guess they came like that. Anyhow, check!

Next, two EPROMS and a memory chip, check!

Next, a large bank of expensive RAM chips. I think these are $10 a piece. check!

Next, my first okay game, I must be feeling better....check!

 

[ifkz]

More RAM, check!

More RAM in column 2, check!

RAM and RAM control chips? in colum 3, check!

Almost done with the chips that are socketed and shared between the two boards. I'm feeling better, a surge did not kill it. Is it going to be the other EPROMs, or the Z80, or something else????

 

[ifkz]

Uncle...
I got down the the CPUs on both the sound and main board and replaced them with other Z80s. I get full error tones in self test now. Sometimes it is only the battery backup ram, which is eight beeps in a row. Other times I got 8, 9, 10, and 11.

Zippo on the screen though.

At least now I know everything in the sockets is okay.

 

[ifkz]

FIXED FIXED FIXED FIXED

I hate working on pre JAMMA stuff, I really do...turned out to be one or more of three socketed logic chips....I had spares that I had pulled off of the scrap sets that came with these. I almost threw them away....
Take your pick of either:
P8612 DM74ALS245AN
SN74532N
M3-7611-5 8035

More good news: I should have proper supports for the set coming by way of a good friend tomorrow. I'll be putting electrical tape on the bottom of each so they are not physically touching the ground plane as this has no mask left in that area.

 

[omegaman]

Good job ......I had my hands over my eyes when I saw you started pulling all the chips out lol

 

[ifkz]

Yep, a case study in something that is no ones fault when it comes to these old boards. It was working perfectly when it left your place, the postal system did its job getting it to me, and I didn't short anything out when I was adjusting things. Just old logic chips burning out when they are well past their expiration date. Glad this had a happy ending, I had nightmares about having to eat another $100 just in shipping to get it back to you for a diagnostic.

Whew! I should create a post about my linear power board, but that is going to be at a later time after this lengthy repair.

 

[omegaman]

Right, I sold an Asteroids game to a guy that lived 250 miles away. I had owned the game for a good 15 years and it was in perfect working order when it left here. He got it home and plugged it in....just garbage on the screen. I told him to send all the boards back. Turned out to be a couple of chips dead in the X output stage of the game board. I didn't charge him for fixing it, i figured I would be pretty pissed if I had driven all that way. I'm sure these games have some kind of soul....they don't like being sold that's for sure.

 

[ifkz]

Got and installed my brackets for the set tonight thanks to a local buddy. So this scrap set is finally complete again after who knows how many years, and at least three techs working to get it going again. Omegaman did the heavy lifting by finding all the bad chips. The original tech tried to save it with new sockets but gave up and stripped the set after a trip through the dishwasher destroyed the mask. I made it complete from scrap boards, replaced broken parts (broken pots, yanked out components), paid the repair bill, and troubleshot it a bit. Now I just need to find a cocktail for it to live in and another game will have been saved from being trashed. Good feelings.