I was referring to the MPU CPU sockets and EPROM socket. Sorry, should have been more specific.

That's not entirely true:
"On *some* system 11 games (mainly 11 & some 11A) some sound cues are generated on the CPU board, these leave the CPU board and are mixed with the other sound cues on the sound board, and then the mixed signal is returned to the CPU board to be amplified. On some other system 11 games (some 11A & 11B), the voices are generated on the CPU board, trucked over to the sound board and amplification and mixing happens there. Finally, on some 11 games (*all* 11C), absolutely nothing happens on the CPU board."

Shorting the speaker lead to ground could kill a final output amplifier, but it won't damage any logic circuits. Evidence that the final output is working: you have other sound effects.

What you need is someone with a Jokerz to assist by comparing your pin-to-pin findings. If you don't know this, many pins will often appear to be "dead" depending on the particular sound or music being played simply because that bit is sending a logical binary zero. Keep in mind that when comparison troubleshooting this way that that both machines would have to be in the same state to obtain a valid test (i.e. each machine placed in a specific music/sound effect test and then make the comparison)

If I had a Jokerz I could help you out this way. Maybe someone will step up for this.

No. Roughly 0VDC to 2VDC is typical (depending on the logic family) OVDC is a valid reading on a functional digital logic IC.
http://www.allaboutcircuits.com/vol_4/chpt_3/10.html

I guess that would come down to bit rate and whether or not it needs to utilize all the address lines. If the audio is only running at 8-bit, it would only be using 1/2 of a 6802's address lines. I believe those Yamaha chips function at 8-bit.

This one is going to be very difficult, as this board was so unique to this game, and there is next to nothing in the way of information out on the 'net on its theory of operation. I can't even find datasheets on most of the ICs you are looking at. The static ram 2064 has a datasheet out there, and of the pins you mentioned, one is N/C (no connection, thus not used) and the others I higher level address pins (A6, A7, A8, A9...) and so may not even be utilized.
Until you have some reliable information on what should be happening on that board, it is going to be next to impossible to troubleshoot.

This sounds likely. Get a new one and pop it in, see what happens. $4 to see if you're right.

As for differing sound volumes, I'm going to assume both the mpu and sound board have sample eproms on them, and say it is probably the volume difference between the MPU samples being sent to the board and the soundboard sample generation. If it doesn't have a trimmer to mix levels where it sums the FM & sample channels together, then it is going to be whatever set values they used. Easy to adjust though, replacing either one of the resistors in the summing network with a slightly different set value, or wire a trimmer pot as a variable resistor in line that fits within the range of the original resistor value. There may be an even easier way than that, if I had the schematics, I could instruct you on how to do that. Get the FM synthesis working first though.

Yeah, that is what I was referring to. Look and see if your Grand Lizard has this IC. Anything that uses Yamaha FM synthesis needs this companion D/A IC and will have it. They should be socketed.

Probably a safe bet. Buy the sure thing to get it going, then the crapshoot, nothing worst than replacing a broken part with a broken part. Those are the trickiest debugs there are. I test all ICs and transistors now before installing them.

That should be easy to fix though, well documented. Lemme know if you need any specialized ICs for it, I have all of them laying around here.

check any caps that look suspect. There could also be a tantalum cap pulling that down. I had one on a fish tales board go the other day. Newer game but all games are victims to bad caps.

Or....shorted. I had no voices/effects on my F-14 Tomcat (also a Williams System 11) It had a shorted cap on the CPU board, and simply clipping one lead on the cap restored the sounds, until I could get a replacement. That said, I am not familiar enough with Jokers - but just letting you know that a cap open or shorted can be a problem.

Replace the board with a rottendog MPU.
I just replace mine due to the same problem + a display issue.

Popped in the new board (you can get them with or without ROMS) works like a champ.
No more battery worries either.

Normally I'd say try and fix the MPU, but in this case that may be the best bet, that or a repaired original.

I actually have an original jokerz cpu in perfect shape if interested. Never even been repaired. Your original has bad acid damage so I would swap in another unless you want to do MAJOR work! Would be a great learning board though. Its already destroyed so your not hurting anything by trying to fix it.
Good luck. Sound repairs suck...lol Just ask my haunted torpedo alley..

I have two badly hacked up SYS11A MPUs if anyone is interested in them. $100 for both? One of them actually boots, but had some trace damage on U27 and has a few jumpered points, so I wouldn't trust it. One looks like someone took a screwdriver to the board in a fit of rage and needs the POR rebuilt. Both had alkaline leaking on them. I'll take pics if anyone is interested. I don't have time to play around with them.

I'm just chiming in to this thread as I have a nearly the identical set of symptoms with my Jokerz. I apologize if this is against pinside etiquite to post symptoms in an existing thread -- I don't mean to hijack the thread and can certainly start a new thread if that's better.

Here's what it sounds like when it starts up (I thought maybe a grounding issue?) https://goo.gl/photos/BTDfjZRtH2wtEmYq6

The game has a very loud hum (more than the standard notorious Jokerz humming, I think) and I notice a bunch of RF interference while I was filming using my phone: https://goo.gl/photos/1KuKjF9Pk7QX8rtm9

But the gist of the problem is that music simply doesn't play, in-game or in the music tests. I'm unsure if that's related to the loud hum or not.

I have reseated the rom on the sound board, and the other two sound roms on the CPU. No difference, but when I took a closer look at the CPU, I noticed a fair bit of what appears to be corrosion.

I also 2x checked the sound wiring bulletin and everything appears to be connected correctly.

However, when I unplug the connection 1J16 from 11J3 (Sound Input from CPU), I notice that there is no change in behavior. Sounds/speech still plays, but music still doesn't.

My concern is that the CPU isn't outputting the music due to the damage. I think my next step would be to try to clean up some of this?

11665887_10152881319275588_373512381_o.jpg

JordanB, I cannot help much but I have a Jokerz with working sound and I can give you a point of reference: My boot up sounds just like yours up until the horn-fanfare. e.g. I hear the rising tone, the electronic thump, the hum. That is all there. However once mine is done booting I hear a single chime not a full fanfare like your machine.

I am definitely not a pin repair expert but the fact that your pin seems to be playing the wrong sound suggest to me the sound system isn't the problem but perhaps the CPU board, like you say.

Oh thanks oohlou. I'm starting to suspect sound ROMS or board problems, but this is new territory for me.

)

Yeah, that's actually quite a lot of corrosion that appears to be in an advanced state. If it has migrated into those IC legs, it can easily damage the fine connections inside. If you don't have problems now, you likely will in the future.