Joust sound board troubles

WiiKnee

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So, after a lot of advice from everyone, I rebuilt my monitor chassis on my recently acquired Joust and the picture looks great! Now, on to a new trouble spot.'

From day one, the sound was working just fine. I rebuilt the chassis to fix a blown flyback, put it all together and everything worked great, including the sound. I shut it down and gently pushed the machine into it's spot. I turned it on - no sound.

I read many threads on this, but my problem seems unique.

First, I rebuilt all my connectors on the PCB's and did a cap kit on the PS. Power seems good. I get sound when I hit the test button. In Test 4, I get some sounds, others try, they start good, but end up as digital garbage and eventually the sound stops all together. When I ground out the signal molex connector on the sound card, same things happen - a couple work, other turn to junk and eventually quit.

I am only getting 10.76v at the 12v TP. At the molex connector going into the sound board, I am getting 11.76v. -12 and 5v are in spec.

Does this sound like a cap kit fix from Bob?

Thanks for the help!

Chuck
 
If some of the sounds are garbled, that sounds like the Sound ROM. The other possibility is that the PIA on the sound card, which drives the D/A converter may be going bad.

ken
 
Ken,

I don't think it is the ROM as soon as a garbled sound is initiated, the sound card fails and the game has to be reset to get any sound at all. Do you still do WMS board work? I think it is probably something simple, but I just don't have a proper test bed. Is having 10.7 volts at the TP considered too low and a possible cause?

-c
 
Yes I still do Williams board repairs.

That depends on the testpoint. There are 4 testpoints. They should read (From top to bottom)
TP1 = +12VDC
TP2 = -12VDV
TP3 = Ground
TP4 = +5VDC

Testpoints 1 & 2 are unregulated so the voltages may vary and not be a significant issue. If Testpoint 4 is more than +/- 0.5VDC from 5VDC then there is a problem in the voltage regulation circuit.

As far as I can tell from the schematics, the +12V is only used by the amplifier and the -12V is only used by the D/A chip.

I don't think it is the ROM as soon as a garbled sound is initiated, the sound card fails and the game has to be reset to get any sound at all.

That actually does sound like a bad sound ROM. The sounds are not just samples, they are actually like little programs running in the ROM. So if the ROM is partially bad it could crash the processor or hang it in an infinite loop which would require a reboot to clean up.

ken
 
Great info, Ken, thanks!

I do have a working Defender here, could I just swap my Defender sound ROM into Joust to test it out?

TP1 is at a steady 10.6, but since that isn't running logic, I guess I am not too concerned. I am 5.01 on TP4 :)
 
As far as I know, there should be, but it may not look like your Joust soundboard, it may be the older type:

http://www.arcadesolution.com/sound.html

Good info - looks like I have the old type with a different EPROM.

So, I revisited the problem. It just is not very consistant so it is hard to pinpoint. Sometimes the corrupted sounds will clear up, sometime not. Sometimes none will work. It sounds kinda like a bad connection on the ROM IC, so I installed a new socket but it didn't make a difference.

So, I am pretty new to the vids - does anyone know how I can get a new Joust sound ROM??

Thanks a ton!

Chuck
 
Good thought about the Defender sound card, but it uses a different sized ROM. I'd have to check, but I don't think the older Defender sound cards are jumperable to accept the Joust sound ROMs.

There are several people here that can burn a new ROM for you. Probably one of the best is Steph at Hobby ROMS (www.hobbyroms.com). His KLOV username is Steph. Given that you are in Michigan, there should be a few members near you that can burn a new ROM as well. Ordinarily I can do it, but I think I am out of the correct ROMs right now. You might want to either contact Steph, or start a new posting asking for ROM burning help in Michigan.

ken
 
Good thought about the Defender sound card, but it uses a different sized ROM. I'd have to check, but I don't think the older Defender sound cards are jumperable to accept the Joust sound ROMs.

There are several people here that can burn a new ROM for you. Probably one of the best is Steph at Hobby ROMS (www.hobbyroms.com). His KLOV username is Steph. Given that you are in Michigan, there should be a few members near you that can burn a new ROM as well. Ordinarily I can do it, but I think I am out of the correct ROMs right now. You might want to either contact Steph, or start a new posting asking for ROM burning help in Michigan.

ken

Thanks Ken - order placed from Steph!
 
Well, I got a new sound ROM, and it helped a little, but still the same problem of certain sounds corrupting and then timing out the sound board.

So, I replaced the PIA chip and it is even better. Will play for awhile with all sounds, then the same thing happens. Sometimes, after a sound corruption, it recovers. But, the sound eventually completely fails and shuts down until a reset.

This doesn't seem at all logical to me. So, perhaps the trouble is not in the ICs since it works fine for a short time before failing. Could this be a capacitor issue? I haven't replaced any caps on the board. A logic probe on key chips tests out good.

Thanks for any help!

WiiKnee
 
It wouldn't hurt to replace the caps. You should probably also watch the +5 voltage line. I had one that the voltage would dip depending on the sound. It turned out to be a bad connector and a bad fuse holder. The fuse holder was not clipping tight enough and it had some corrosion so that the voltage was fine when it was quiet, but it would drop when it got busy because the voltage regulator couldn't draw enough current. Cleaning the fuse clips and bending them tighter along with reflowing the solder joints on the header finally fixed it.

ken
 
It wouldn't hurt to replace the caps. You should probably also watch the +5 voltage line. I had one that the voltage would dip depending on the sound. It turned out to be a bad connector and a bad fuse holder. The fuse holder was not clipping tight enough and it had some corrosion so that the voltage was fine when it was quiet, but it would drop when it got busy because the voltage regulator couldn't draw enough current. Cleaning the fuse clips and bending them tighter along with reflowing the solder joints on the header finally fixed it.

ken

PM sent, Ken - thanks for all the advice!
 
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