I’m attempting to help a friend with an issue with his Jokerz. Basically the music will at times cut out. And i also notice the volume of the music relative to the sounds is very low. Adjusting the volume pot increases both music and sound, and when you get the music where you like it the sounds are way too loud.

I played a few games and for the most part the music was there. But i did notice between balls or at the end of the game the music would sometimes die, but then next game it would return.

To date - the owner had replaced the game ROM’s which did not improve the issue.

Test for the audio board and MPU sound audio test checked out.

I pulled the audio board which is unique to this game so i couldn’t use a board from any of my system 11’s. The headers had been previously reflown and one capacitor had been reworked. Aside from the flux left on the board it looked ok - but decided to clean up the pins and reflow them anyway. Reinstalled and no change. Pins looked ok as did the headers.

Caps on the board are original so i ordered new ones. Can’t hurt. I’ll do the power supply and aux power supply while i’m in there. I tested voltages at the power supply and only one i noticed that was out was the -12V which read -14.5V with everything connected. I know its unregulated but not sure if that should be closer or not...

So that’s what i know so far. While i’m waiting for some components to come in - i thought i’d ask if there was anything else i should be looking at when i get back to the game? Any tips would be appreciated!

Thanks.

Bumpidy

Well the good news is we no longer have intermittent music. The bad news is we have now audio. Just i loud hum out of cab speaker. Not the typical Jokerz hum. Constant level regardless of where volume pot is adjusted.

So here is what has been done. Owner had someone burn new ROMS for audio board and MPU. What i have done to date:

1) replaced all electrolytics on the board. While doing this i rebuilt power supply. PS voltages all test ok.
2) reflowed headers and other component leads on the board. There was some previous work done so cleaned up that and then cleaned off all the old and my flux. I hate it when flux is not cleaned off. It takes no time lol

* at this point there had been no improvement in the audio. Sounds were fine but music low and intermittent. Though i did determine the low level was in the adjustments (someone changed it). So really the issue is narrowed down to intermittent (failing) music. Sounds were fine.

3) replaced sockets on the IC’s and roms that had them. Used new machined pin sockets, installed with an old ic to get proper alignment. Also replaced the two TDA2002 amps at the same time. This was a mistake. Because now the audio was worse. Is it the amps, did i mess up the socket job? No idea which of these made it worse. The TDA2002 i got from Marco. My desoldering iron was down (see my other thread where i fixed it yay). So i cut the legs off the amp as my solder sucker wasnt getting it.

At this point i suggested to the owner to bring the game over to my workshop so i could test it easier than running back and forth to his house. Had i had done this earlier i would of changed one thing at a time and i would know exactly what happened.

4) swapped out the MPU with one of my SYS 11’s. same. Swapped out ribbon cable with a known good one. Nope.

5) removed amps and ordered a set of audio amps from a different and much cheaper source. Love Marco but 10 bucks for an amp is pricey. They dont make them anymore i get it. But still.... installed new amps, new heat sinks as you can only bend those tabs back and forth so many times. No improvement.

Honestly i think the replacement amps are the issue. They are the same model. TDA2002’s. all i know now is i have the hum out of cab speaker. And no noise at all out of speaker panel. The plus and minus 12v on audio board is fine at least at the headers.

6) drank a beer. Small improvement in my mood. No improvement to audio.

Not sure what to check next. Or if the IC amps are compatible. I could try putting back one of the original amps. The one i didnt cut out.

Any ideas or advice on what to check? When i agreed to help it was on the assumption i could test with known working audio boards. I’ve never owned Jokerz and of course it has a unique audio board which threw a wrench in that plan. My next thought was to tell the owner i had a break in, and burglars left everything but the board.

Thanks for reading the novel.

Game sounds are consistent and were adjusting fine with volume pot in cab. Only the music was cutting out - and would return after you stopped for a bit. So i was thinking something was changing with heat. I didn't suspect volume pot as most likely root cause as the sounds were unaffected. I could try swapping one out to be sure though. Thx.

Seems i cant post a video. Shame. Because you would see a jokerz with loud music singing away

Had nothing to do with anything i touched (directly) - i noticed tonight a little splash of solder on the back of the board. Probably my desoldering pump spit it out. It does that when its a little plugged. Cleaned it up and voila