Bombjack Twin Sound Problem

mastercello

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Hi everybody...

...another day another problem with a pcb.

This time i'm trying to get a NMK pcb working (Bombjack Twin).
The problem is the sound, half of it is playing nice and without error.
The other half (like every 3 second) the sound is kind of distorted and stuttering.

There are two ROMS where the sound is coming from, also involved are two OKI M6295 and two LS245 bus transcievers.

Things if done:
- I desoldered already the ROMS and they check out fine on ROMident. Also if i take out the ROM which contains the "bad" sound half there is obvious no "bad" half sound anymore - just silence.
- Changed the OKI from the "bad half" with another one from a scrap board.
- Checked all connections between - ROMS, M6295 and NMK CPU - all fine.
- Burnt new sound Eproms just in case.
- Changed both of the LS245.
- Resoldered the NMK Sound CPU
- Changed all the elko capacitors
- Clock is connected together for both OKIs

Unfortunatly i have no other pcb to test the area around the involved chips.
The sound cpu seems to be a NMK custom - so no getting anywhere here neither.

Any ideas?
Somebody with a schematic of any NMK pcb?

I have attached two pictures of the pcb (actually Sabotten Bombers which is exactly the same layout as Bombjack Twin).
http://imgur.com/8PjGc
http://imgur.com/9OZXu

Thanks a lot!
 
Am out of puff on this one, see my last post on AA tho, other than that I would need to get the board on my test bench and would follow my nose.
 
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