Jokerz! plays sounds, but no music

[Jordan B]

I have a Jokerz! that I picked up a few months ago that took some battery damage to the MPU. I'm under the assumption that is the cause for this behavior, but wanted to see if anyone else might have some ideas before I shell out for a replacement board.

Here's what it's doing:

- During music tests, each test plays a different sound effect (rather than the expected music)
- During gameplay, no music plays at all
- There is a hum rather than music, but that might be the notorious Jokerz hum
- All other game functions seem good.

I've done a few things already, including:

- reflowing solder in the sound board header pins
- replacing the sound board <-> MPU ribbon cable
- burn new game and sound ROMS

Next step, I think, will be just getting a new MPU and hoping that solves the problem. However, if anyone happens to have any different ideas, I'd be thrilled to get this problem licked!


Jordan.

 

[Menace]

Check the small 8 pin op-amps on the left side of the MPU. If they are socketed, swap them and see if anything changes.

D

 

[Jordan B]

Hmm, had to go to the manual for that one. Looks like these are U4 + U5 (P/N 5370-09321-00). Not sure how to check them out other than visual inspection. Unfortunately they're not socketed...


Are these what you were referring to?

 

[Menace]

Yep, those are the ones I'm talking about. I had a client's F14 in my shop with a similar issue, and half of one of those op-amp's failed. If you're good at PCB repair, take them out and install sockets and swap them to see if the issue either goes away or if the music comes back and the speech goes away.

D

 

[Jordan B]

Thanks much Doug! I'll wait for my replacement board to arrive before messing around with removing the components, but I have some replacements inbound for when that day comes. Fingers crossed! )

 

[spiroagnew]

On a lighter note, perhaps this is the ultimate mod for Jokerz: silence! That music is so annoying it would be considered an improvement!