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Hi all,

I've been working on this Pole Position and almost got it back completely.

For the sound, I've got the engine noise and speech working fine. The other sounds are not showing up at all, but I have evidence they are working, at least some of them.

For example, if I check "CHANL2" from the 54xx custom I can see the explosion noise is occurring. However, it's never getting selected at the multiplexer (the 4051B at 5B). This is a Namco PP by the way.

The 4051B should be picking sounds based on the inputs at pins 9, 10, and 11. But what I've found is that they get turned on during the start up then never change. They are all high, which selects CHANL4 which is the speech channel, so that would be why that's working.

I'm stumped as to why those selection bits never change. I have removed and verified the 273 that latches those bits, the PROM at 9H that creates the SBCLK1, SBCLK2 and SBCLR signals, and the 07xx custom before it, and the 4051B itself.

The bits come in through the 273 from SD0, SD1, SD3. These bits factor into the Sound Memory and such that all pass properly on the Fluke.

I have another PP board (it's a Namco PP2) and I cans see that the selection bits (at least A and C) should have a signal on them all the time, even when not playing a sound. So it really seems like whatever is supposed to be writing those bits just isn't working. I do have a sneaking suspicion the info being written into the larger "Sound Buffers and Multiplexer" might not be correct as it looks a lot different between the two boards.

Any ideas??
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