Crazy Kong (Falcon) No sounds from EPROMs.

Scucci

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I have a Falcon Crazy Kong (Part II) board here that is producing no sounds from the EPROMs. There are still sounds from the game, but not that are stored in the EPROMs. The basic music, points sounds, hammer hitting something sounds, and basic melodies are all there, but they aren't reliant on the EPROMs.

I pulled the logic probe and started checking around and I'm seeing next to no pulsing in most of the audio EPROM section... off the top of my head the only pulsing I'm seeing is on the 7402 at 2S and only on pins 1A, 2A, 3A, and 4A, the outputs are working as intended (as best I can tell, more coming up on that) and the B's are flopping back and forth as sounds SHOULD be read from the EPROMs (walking, barrels falling, jumping, thuds, etc). The only one that's not flopping is on the first NOR gate with pins 1, 2, 3. Even though the inputs are pulsing and flopping, the output on that one (1Y) doesn't change. I thought it was the chip, but I replaced it and it's still acting the same... It could just be switching at the exact right moment and not causing the output to change...? I checked that pin, in socket with no power applied, and it's not shorted to anything. So the 02 and the next chip in line with that (and 04) should be good?

I have piggybacked a known good Z80 with no changes at all in the missing sounds (figured I'd atleast get some jibberish).

Any more ideas on what to check?
 
I've got a Falcon board (not CK Part 2, it's just regular CK) that has the same problem. It plays none of the sounds from the sound EPROM's (which are actually from the Japanese version of Crazy Climber). It had a bad AY-3-8910 as well, but putting a good one in makes no difference. The bad one made the music wrong. If I put the bad one in another working board, I still get the bad music, but get the other sounds as well (running, jumping, Kong chest beat, etc), although I also get a few other Crazy Climber sounds occasionally (the "yes!" when I start running, and sometimes part of the falling sound)
 
I replaced the 0.001uF ceramic caps around the LM3900 with new caps, made no difference. Check resistors in the sound circuits, all checked out. So it doesn't appear to be any non-IC components failing and pulling an important line high or low... So, there's some IC not acting right here, and I can't find the little bugger for the life of me.
 
I printed out some more pinouts and better schematics today and started looking again.

No joy... still.

I keep coming back to that pin on the 7402 at 2S... is there any chance of someone with a working Falcon CK PT2 board, and a logic probe, checking that first gate on 2S (pins 1, 2, 3)? I just keep having some feeling that pin 1 should change it's state when the sounds I'm missing are supposed to be playing (like the other gates are)...
 
I know this is an old thread, but (thanks to some people over at dragonslairfans.com) I recently fixed that board I mentioned earlier in the thread that was missing all the Crazy Climber samples, and it was a bad LM3900. Piggybacking a good one over the old one brought back the samples. Did you check the LM3900 itself? I see you replaced some caps around it.
 
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