Mappy garbled sound

Torin

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I have a Mappy pcb running through a Galaga cabinet. I can hear the sound pulsing to the beat of the music that plays but it is just garbled pulses instead of music. Any ideas what this could be? Could it be because of the Galaga harness? I thought they were wired the same. Probably a board issue?

Any help is appreciated.

Torin
 
Looks like some work has been done on the amp (LA4460) in the sound section. It has quite a bit of solder around the legs of the chip and I found a cold solder joint on the back on one of the pins. Touched it up but it didn't improve anything with the garbled sound. The capacitors on the board all measured good on my ESR.
 
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The pinout is the same, shouldnt be a problem there. Is the amp working? Do the thumping sounds get louder when you adjust the sound pot up? Usually the 4460 either works or doesnt. When it dies it tends to crack open and lets all the smoke out.
Anyways, start at the amp and work your way back.
 
The pinout is the same, shouldnt be a problem there. Is the amp working? Do the thumping sounds get louder when you adjust the sound pot up? Usually the 4460 either works or doesnt. When it dies it tends to crack open and lets all the smoke out.
Anyways, start at the amp and work your way back.

The thumping sounds do get louder when I turn up the sound pot. So, I take it the amp is working. Is there a sound prom that I should look at?
 
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Is there a sound prom that I should look at?

There is:
Code:
 2079      ROM_REGION( 0x0100, "namco", 0 )    /* sound prom */
 2080      ROM_LOAD( "mp1-3.3m",   0x0000, 0x0100, CRC(16a9166a) SHA1(847cbaf7c88616576c410177e066ae1d792ac0ba) )

Location 3M, according the the info in the MAME driver.
 
There is:
Code:
 2079      ROM_REGION( 0x0100, "namco", 0 )    /* sound prom */
 2080      ROM_LOAD( "mp1-3.3m",   0x0000, 0x0100, CRC(16a9166a) SHA1(847cbaf7c88616576c410177e066ae1d792ac0ba) )

Location 3M, according the the info in the MAME driver.

Cool. Thank you. Is there a good way to tell if this chip is bad? Anyone know where I can get a replacement?
 
mappy distorted sound

yep, turned out to be a bad sound prom at 3m.
 
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