A new problem, what a surprise! Bally related.

dieseldogpi

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Hey everyone, I finally figured out what was wrong with my displays the other day, and no less than an hour later i noticed I had no sound on my Mr and Mrs Pacman. The squawk and Talk board looks like it boots, i get 5 flashes of the LED, I also can hear the amplifier kick on, but otherwise, no sound. I hope this is my last problem with this machine. Thanks guys.
 
No ideas? I for cracked solder joints and I didn't see any. In the past I was getting jumbled sound, but this went away when I re-seated the chips (I know, i need to change the sockets), I tried that again and nothing this time. Is there a particular chip that could be causing this? Something else perhaps? ANY ideas would be appreciated.
 
First place to check is the power circuit on the S&T board with all of the caps in it. Verify that all of the voltages are correct. You probably have a bad cap. Before you just slam a cap kit into it, verify your voltages.
 
If it's flashing 5 times that tells you it's booting. Or at least should be.

The first thing to do is press the test button. Do you hear any sound? If you do then your S&T board is probably working fine and the MPU is not telling it to make sound for some reason. If you don't get any sound with the test button then the problem is likely isolated to the S&T board. I would first suspect a problem with the amplifier circuit because it's booting but in any case I would be pulling it out and testing it on a bench. Check the +12 going to the board with it in the machine too but we pretty much know it's there because it's booting.

The S&T has it's own power supply for the +5V (voltage regulator and filter caps). It also has a -5V circuit derived from the general illumination voltage. That's kind of weird. You can check all that stuff but it doesn't really seem like a power supply problem.

So... first decide if you even have a problem with the S&T board by pressing the test button.
 
I am referring to the power section of the S&T board not the power supply itself. The caps are notorious for failing and killing the sound.

Example: Had a Flash Gordon that worked great on the bench, put it in the machine and nothing. On the bench I was feeding power through the test points and bypassing the power section of the S&T board. In the game power was running through the power section of the S&T board and being killed by two or three bad caps.

Sorry if my previous post was unclear.
 
I am referring to the power section of the S&T board not the power supply itself. The caps are notorious for failing and killing the sound.

Example: Had a Flash Gordon that worked great on the bench, put it in the machine and nothing. On the bench I was feeding power through the test points and bypassing the power section of the S&T board. In the game power was running through the power section of the S&T board and being killed by two or three bad caps.

Sorry if my previous post was unclear.

I would still press the test button first :)
 
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