System 80B sound board troubleshooting..

Sprout

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...anything out there - anything at all? All the guides and info. I'm finding are for early system 80 board versions (IE, Black Hole, Haunted House - the stuff covered in Clay's old guides and elsewhere), but really coming up dry with anything useful for the later version of the System 80B sound board & aux. sound board. In this case, it's one from a "Big House" - sound effects are working ok, and I think are all there - but no music whatsoever.

Two 6502's on the sound board; one seems specific for the music. I can probe the data lines on the processor, and they're active - but when I probe specific data lines, the processor seems to lock up - everything goes to a logic high - normal sounds still working.

Reset the board using the on-board button, and it's active again. Odd thing is that it's like there's no communication to the aux. sound board - the data lines are never active on the sound chip (forget the part number, and no schematics handy) - they're stuck low. Cable looks ok, but having it checked out to be safe.

Waiting on the manual to come in from PB Resource (scanned manual I have is very poor), but curious whether anybody has any useful repository of basic troubleshooting info. on these boards in the interim, or a complete set of decent quality schematics for it.

Thanks!

Brent
 
I'm with you brother. My 80B board just stopped and I'm a little unsure of the steps to take untill I get a manual. I have the Hot Shots and no sounds on any pin makes the pin suck.
 
There are two processors (6502) like you said. Each with their own RAM and ROM. If the CPU and RAM are in sockets I would swap them one set at a time just for grins. If the problem changes you've found the problem. Swapping the ROMs is not going to work but you could pull them and confirm them with an EPROM programmer if you have one... AND the ROMs.

You could also check the NMI and IRQ pins on the processor. There is some logic connected to them that could have failed.

After that it's basically standard 8-bit computer troubleshooting, unfortunately. There are no good guides specific to System 80B sound that I'm aware of.
 
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