Cackling

Joined
Oct 21, 2010
Messages
559
Reaction score
2
Location
Belgium, Wisconsin
What would cause cackling noises on my Karate Champ? It's not constant. Sometimes loud, sometimes quiet/muffled. It's always when the referee is talking. I thought it might be a blown speaker, but they looked good and the wires all seem to be in good shape. I turned down the volume of the game and that helped a little, but not completely. The longer I play, the worse it gets too. Any ideas??
 
Sound amp is usually mounted to a heat sink with bolts. As Tomtime said look for pot and caps.
 
You audio power amp should be a TDA2003. It has 5 pins in a zig-zag arrangement. It probably should have a heat sink on it.

The "audio section" is in the upper right of this pic (the area with the blue electrolytic caps):
http://maws.mameworld.info/img/xt/pcb/kchamp.png

Some of the electrolytics in the audio path include: C17, C9, C10, C19, C22, C123 & C120.

Does anyone know if the speech in KC comes out of the MSM5205? I wouldn't think the PSG does it...
 
So is it bad if mine does NOt have the heat sink on it?

You audio power amp should be a TDA2003. It has 5 pins in a zig-zag arrangement. It probably should have a heat sink on it.

The "audio section" is in the upper right of this pic (the area with the blue electrolytic caps):
http://maws.mameworld.info/img/xt/pcb/kchamp.png

Some of the electrolytics in the audio path include: C17, C9, C10, C19, C22, C123 & C120.

Does anyone know if the speech in KC comes out of the MSM5205? I wouldn't think the PSG does it...
 
Maybe. You said the problem gets worse the longer the game is on... that would be consistent with a heat-related issue.

Turn in on for a while, play it (so the audio amp gets worked some), then try touching the tab of the audio amp... if it's hot as shiznit, you need a heat sink.
 
Turned it on and after just a few minutes the audio amp was getting pretty warm, but the "cackling" was happening almost immediately.

Maybe. You said the problem gets worse the longer the game is on... that would be consistent with a heat-related issue.

Turn in on for a while, play it (so the audio amp gets worked some), then try touching the tab of the audio amp... if it's hot as shiznit, you need a heat sink.
 
Could be the damage is already done to the amp IC.
Or it could be a cap.

You could use an amplified speaker to probe before the amp, and see if it's OK there or not.
Or you should just replace the caps and/or the IC.
 
Back
Top Bottom