Taito Space Invaders sound issues - Solved

Well damn, it's been running great but this evening the sound started to cut out completely. I was touching a few spots on the board and the NTE990 is wicked HOT.
 
Yeah, I was wondering if that was going to happen.

The manual shows that chip having a pretty decent heatsink on it. I wonder if yours is missing (which may be what killed the chip for the guy before you.)

Does the sound return to normal if the game cools down?

I'd try finding or making some kind of heatsink for that chip.
 
I think you're right @andrewb that area on my board is suspicious, and yes in fact the sound returns even after a few minutes of not playing.
I'll look into a heat sink of some kind, I was thinking about a small PC type of fan also.
 
I don't think you need a fan. The heatsink in the manual is one that is very thin, and large.

You could get a thin sheet of copper (or even just an actual heatsink) from ebay and just glue it on with some thermal glue. You just want it to be on the order of the size of the one in the manual, many times bigger than the chip.
 
I'll get a heat sink on the way and hopefully that will do the trick, probably a spare NTE990 while I'm at it.
 
Original schematics show an LM377 = LM1877 there, not an NTE990 (which appears to have a similar pinout, but may not be an exact match -- the datasheet sucks).


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Good point @HudsonArcade thanks.
I'll put one in and see how the machine responds. I'm going to put a heat sink on whichever ends up in there.
 
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