Lunar Lander Hum

Braido

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My Lunar Lander has developed a load hum, any idea what i can do to correct this? I was thinking it must be something to do with the Power Supply? I think i remember reading somewhere a while back about Asteroids having the sames issues?

Any suggestions would be great, thanks


...
 
Yep

One of your audio amps is bad. Use TDA2003. I was swap one out at a time if you have two on the board. Your hum will go away.
 
I'd replace them both..simply because of age..the other one might fail.
 
FWIW, my Asteroids had a (not too loud) humm that turned out to be bad connections in the main edge connector. I'd agree that a LOUD humm seems more likely to be an amp. But it might be worth taking a moment before heating up the soldering iron to lightly twiddle the edge connector and see if it changes...
 
Could be the main board or the AR board. Swap out the AR board from another machine (if you have one :)). If it's coming from the game board I'd first suspect the LM324 at R7.
 
I went though this a wile back. My hum was caused by one of the 2 TDA2003 amps was bad. That would be my guess.
 
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