This one has me baffled from a Space S*uttle and has become a BFH (Board
From Hell):
The board came to me already worked on (fixed everything properly but the sound section). I used Leon's test chip and all worked except the sound. I found the 6821 in the sound section was bad and replaced it. The sound seemed happy by pressing the on-board diagnostic switch but when I sent it back to be tried, the owner reported this situation (he has a spare board that worked fine in the pin for comparison): "It doesn't play 2 sounds when you first start it up. All the other sounds seem ok, but when you get the extra ball or Special ( for the spell shuttle value) or when you get the multi-ball there is supposed to be an explosion sound. When we run the diagnostic test from the button on the coin door, the 2nd and 6th sounds (out of 7) are not there. But if you let the test run through again, the 2 missing sounds are there. These 2 sounds make the explosion sound. After you let it run till the sounds are there, then put it back in play mode it works and makes the explosion sound and plays fine. So far every time we turn the game off and start it up again the 2 sounds are missing, but running the test makes them play again." I've replaced both 6821s and 6810 ram and 6808 cpus, both eproms and checked all connections for continuity. I don't have a sys. 9 pin or test rig to test and debug the board in and the owner is not within driving distance. Any help would be appreciated. If I can't find the prob, if anyone has a system 9 machine and can finish the repair, I would send it to them and compensate them for their work (in parts or $) as I don't want to string out the owner of the board. Thank You and Best Regards, Bill If you ever want to (un)subscribe yourself with TTL, you can send mail to: <Majordomo@flippers.com> with the following command in the body of your email message: (un)subscribe techtoolslist or from another email account, besides xxx@yyy.com: (un)subscribe techtoolslist xxx@yyy.com