DE sound Simpsons

[BMHouze]

Currently working on my brothers DE Simpsons. The head speakers are present but they are not really hoked up. My tech says the head speakers needs a petentiometer.
Just want to be sure we are the right track. Also wondering if this is common and if the head speaker hookup are suppose to be connected. Could be for a premium upgrade as the soundboard could very well be multi platform.

 

[sylvain]

According to the limited info displayed in the game manual & schematics (pdf available on ipdb),
there is only one stereo (dual ganged) potentiometer in the cabinet, bot front right.
I do not think there would be additional potentiometers just for the head speakers in this machine
(someone who owns such game could confirm).

- Sylvain.

 

[BMHouze]

There are 2 on the schematic. 3 amps aswell on the soundboard logic diagram. Seems only the center is working. Left and right channel don't work. Looks like we need a new 10k potentiometer. Looks like the cabinet may be on a non volume controlled circuit....
More we screw with this the more we seem to learn.

 

[sylvain]

Looking at the sound board diagram from a DE Back to the Future (should be similar to yours),
the stereo volume control ganged-potentiometer in the cabinet feeds a Left and right Inputs audio,
after the volume control from the cabinet, to the Left, Right, AND Center amplifier chips inputs
on the board. All 3 amplifiers get controlled by the same dual-ganged potentiometer.
No additional pots are required for the head speakers.

If you hear the center cabinet speaker, the head speakers should also work
IF they are properly hooked-up to the sound board, if the head speakers are good,
and if the sound board left and right audio amps are good... (with good electrolytic caps).
It is very unlikely that the volume control is defective if you hear the center cabinet speaker...

- Sylvain.