Frogger no sound

dyno

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I know this topic seems to have been brought up lots but here I go. I picked up a Frogger board, the 44 pin type and finally got around to testing it lastnight. The board works but I can't get any sound out of it. I have connected a pot to it so I am getting sound out of the speaker but no game sounds seem to becoming from the board, when I turn the pot the volume on the speaker does go up and down. Anyone dealt with sound issuses on this type of frogger board? I know the 36 pin board is the more common board.
 
I just got done with a Frogger board with intermittant/no sound a few days ago. Since the sound board has its own CPU and can operate on its own, they're pretty easy to t-shoot.

This one verified rom code OK, would run sometimes for a while then die, other times wouldn't run at all. The main problem was a bad output on the LS245 bus driver, and invalid output from the logic gate that controlled the xmit/rcv direction.
 
Totally from memory but isn't the sound for Frogger powered by the -5V line? I may be wrong about that, but I would check that as well.
 
The -5 is for the op amp driver in the output section. Its a std dual supply setup with +/-5v rails. The digital part of the board will operate without it, but the audio output won't.
 
Found the problem of no sound, there was a broken trace on the main board that the audio wire from the sound board connected to. I have sound now, but it is faint and there is a loud annoying humming sound coming out of the speaker now.
 
Sound is working properly, goes up and down when I turn the pot. The only thing now is there is a high pitch squeal coming from the speaker also.
 
Found the problem of no sound, there was a broken trace on the main board that the audio wire from the sound board connected to. I have sound now, but it is faint and there is a loud annoying humming sound coming out of the speaker now.

would you please post a pic of this for reference.
 
Working on the board lastnight, I think I found what is causing the loud squeal. The frogger board I have is the 44 pin variety and the sound board is connected to the main pcb by 2 sets of long pins that connect to 24 pin ic sockets. When I pushed on the sound baord where the pins are the squealing went away and you could hear the music and sound effects fine. The sockets on the main board are old yamaha sockets and the connection between the pins off the sound board and the sockets on the main pcb seem very loose. Thinking I should try to replace the sockets with better quality sockets so the connection is tight and not looose.
 
Huh? The 44 pin board does not have a separate sound board. It has a rom expansion board. Look at pacman schematics, they are about the same hardware.
 
Thought that was a sound board, that is what the schematic identifies that pcb as. It seems by issue with the loud squeal sound has something to do with the connection between the main pcb and the smaller pcb
 
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