Tutankham Sound (amp issue?)

Scucci

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Got a Tut board here that's missing all sounds, I only get a slight buzz from the speakers when the volume is turned all the way up.

I've started checking out the sound amp with my signal injector... putting neg to pin 3 and pos to pin 2, all I get from the speaker is a click sound when I touch the pins... that's it, no tone.

Safe to assume I need to replace the amp or is there anything I should be looking for. The light buzz in the speakers seems to follow the volume pot just fine, so he should be good there.

Completely forgot... the amp is an LA4460
 
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id test the capacitor with an ESR meter and see if its ok. then i replace the AMP, test/clean the potentiometer. if that doesnt fix it i ohm resistors and then logic probe chips to see if they are pulsing or not for that circuit.
 
Sorry I didn't post a follow up... I kind of stopped working on stuff for a while there.

The amp was bad, found that out when I "borrowed" it for my Time Pilot '84... Didn't officially smoke on the Tut board, but the TP'84 board made it dance. So, replaced the amp, and then I still wasn't getting audio.

... today I was messing with the board again... flexing the board to see if there were any weird traces or cold joints. I started getting audio and kept flexing... then I realized I was only getting audio when I was putting my fingers on the traces for the crystal. Sure enough, if I'm touching the crystal when I turn the machine on... I have audio (slightly sped up a little, but audio nonetheless). So, looks like dead crystal... I assumed that crystal was for the actual game and since it was running, the crystal was good. ... Negative... seems that crystal is just for audio. So... ordered in a few.


"Borrowed" the crystal from my Mega Zone, sound is back up and running.
 
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