(Topic ID: 216897)

Low Voltage for Williams System 6 sound


By ThatOneDude

1 year ago



Topic Stats

  • 10 posts
  • 3 Pinsiders participating
  • Latest reply 1 year ago by ThatOneDude
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#1 1 year ago

When debugging a Williams Gorgar sound(no sound out at all), I discovered that the voltage coming from the transformer at that tap is ~9.4V. According to the schematics I have, that should be 18.7V AC. So, I'm assuming that this is likely the root cause of my problem.
Since the rest of the system seems to power up just fine, I'm inclined to simply replace this particular voltage, with a separate AC transformer. Has anyone else tried this?

#2 1 year ago

If this voltage was off, I don't think you'd have logic voltage, and the game wouldn't boot. The schematics I see state 9.3 A/C, so you're right on the money. Look elsewhere for your issues.

#3 1 year ago
Quoted from CadillacMusic:

If this voltage was off, I don't think you'd have logic voltage, and the game wouldn't boot. The schematics I see state 9.3 A/C, so you're right on the money. Look elsewhere for your issues.

Pretty sure the sound board has its own transformer center tap 12v totally separate from the other 12v that that get regulated down to 5v for the mpu and etc.

Sometimes these voltages read weird when there is no load. What about the test points on the sound board when connected? +5vdc, +12vdc and -12vdc .

#4 1 year ago

Look at the manual on IPDB. Page 20 has the power wiring diagram. The 12v for sound board is very clearly hooked up to the logic power. It's further rectified on the sound board, yes, but they share a source.

#5 1 year ago
Quoted from CadillacMusic:

Look at the manual on IPDB. Page 20 has the power wiring diagram. The 12v for sound board is very clearly hooked up to the logic power. It's further rectified on the sound board, yes, but they share a source.

Looking at page six of the manual(the block diagram): http://www.ipdb.org/files/1062/Gorgar_Manual.pdf
It shows that the input to the sound board is 18.7V AC. I have also traced those wires back to the transformer directly. The logic is not connected, AFAICT.

#6 1 year ago
Quoted from ThatOneDude:

Looking at page six of the manual(the block diagram): http://www.ipdb.org/files/1062/Gorgar_Manual.pdf
It shows that the input to the sound board is 18.7V AC. I have also traced those wires back to the transformer directly. The logic is not connected, AFAICT.

18vac rail to rail. 9vac either rail to ground. Center tap transformer setup.

#7 1 year ago
Quoted from barakandl:

18vac rail to rail. 9vac either rail to ground. Center tap transformer setup.

Right. I posted that as I didn't see a connection to the 12V logic supply.

#8 1 year ago
Quoted from ThatOneDude:

Right. I posted that as I didn't see a connection to the 12V logic supply.

after rectification there are capacitors which keep the voltage up. should be right around +12v and -12v on the sound board test points. Is that voltage low?

#9 1 year ago
Quoted from barakandl:

after rectification there are capacitors which keep the voltage up. should be right around +12v and -12v on the sound board test points. Is that voltage low?

I think I made some bad contact when I was measuring the power originally. This time, I got a clear 19V from the incoming voltage.
I got +12V,-12V and 5V on the test points.

I'll run through the rest of the debugging and see where I get. I've already ruled out the front volume control.

#10 1 year ago

Ok, so it wasn't voltage. Mysteriously, the sounds(but not speech) have started working. Now I'm going to work on narrowing down the cause. Thanks for the posts!

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