Ms Pac sound crapped out help pls

vintagegamer

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On Saturday I had Ms Pac up and running for a birthday party, and she was running at 100%. I went in the afternoon to do a status check in the garcade, and I noticed that when someone was playing the Ms Pac, the sound had been reduced to a staticky garble. It's not like I could hear the actual sounds just fainter, it was actually just staticky-code-ish sounding garble. Nothing that resembles Ms Pac sound at all.

I've owned this game for 4 years now, and this is the first time I've experienced this problem. Could it be a sound ROM issue? Are there common failures on the sound components for this game?

Thanks in advance.

Jim
 
There are no sound "ROMs" but rather small PROMs and discreet digital circuitry with a CMOS switch.

If you have an audio probe or oscilloscope check the inputs and outputs on the 4066. This will help you isolate the problem to before the 4066, to the 4066, or to the amplifier circuit.

This sound issue could be a corroded or dirty pin on a socket chip in that sound section, a bad 4066, or the tiny tantalum cap under the audio heatsink. It can also be caused by many other bad chips such as 7489 RAM.

RJ
 
There are no sound "ROMs" but rather small PROMs and discreet digital circuitry with a CMOS switch.

If you have an audio probe or oscilloscope check the inputs and outputs on the 4066. This will help you isolate the problem to before the 4066, to the 4066, or to the amplifier circuit.

This sound issue could be a corroded or dirty pin on a socket chip in that sound section, a bad 4066, or the tiny tantalum cap under the audio heatsink. It can also be caused by many other bad chips such as 7489 RAM.

RJ

Thanks for the intel, CM- I will take a look around going off of what you are suggesting and see what I can find.
 
Thanks cadillacman,

I went back out tonight and turned the game on to see briefly if the problem corrected itself. Sadly, it didn't.

While playing, I focused on what exactly I was hearing- you can hear a staticky code-like signal being sent to the speakers, and it has the breaks in it where it should as if the actual tones were being generated. It's almost like whatever is supposed to convert the electronic signal into the tones that you hear for the game is not working.

I'll read through what's on the link that you provided and see what I can figure out. The sad part is, this is where my level of expertise (if you even want to call it that) drops off. I can swap out any chip you tell me to that has pins on it, but once you mention the "s" word (solder shhhhhhh), I turn into Edward Scissorhands trying to eat his dinner.

Stay tuned.

VG
 
I recently had one with a bunch of grabled sound. The volume pot would increase and decrease the sound, every indication that the amp was working. The problem ended up being a bad amp.
I actually use a logic probe on the 4066 and you can hear the game sounds with it if they are there. The two proms often have dirty/bad sockets from people pulling those chips alot. The acutal proms rarely go bad unless someone plugs one in backwards.
 
I recently had one with a bunch of grabled sound. The volume pot would increase and decrease the sound, every indication that the amp was working. The problem ended up being a bad amp.
I actually use a logic probe on the 4066 and you can hear the game sounds with it if they are there. The two proms often have dirty/bad sockets from people pulling those chips alot. The acutal proms rarely go bad unless someone plugs one in backwards.

Thanks for the input Riptor- I'll report in once I've found what is up.
 
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