Karate Champ sound issues

[matsadona]

Hi all

I have a strange problem with my Karate Champ (vs.) PCB.
Please refer to this video for mor information. Any help would be appreciated.



I need help to understand what might be wrong with my recently bought Karate Champ (vs) PCB.
As you can see the sound is messed up. Seems to me that it tries to play the melody, but holds the first note...
Also the samples can't play and it all goes "metronome" style...

I have lifted out both Yamaha and the Z80 chips, to see if that help (eroded pins). Also did the same with the 16, 17, 18 ROM's, since I believe they are the sound chips.

[matsadona]

30 views and not a single suggestion or comment?  Anyone?

[matsadona]

Seems that I will have to buy a second PCB since I'm pretty stuck here. And I will need a new setup of ROM and CPU circuits to replace with to narrow it down.
But still, any suggestions (based on similar problems) is for sure appreciated.

[Lilwolf]

Wrong forum to get board level repairs.

did you try klov's forums?  I'm not sure where else to ask.  I used to work with an electrical engineer, and he could eyeball a schematic and a board and figure out in 2 minutes any problem I had.  I wish he was still around. 

[matsadona]

Yeah, you are probably right. I'll register at KLOV and see what that gives.
Could be useful to lurk over there too by other reasons as well

[boardjunkie]

 You need to check operation of the sound board. Make sure 5v and 12v are present. Check for valid clock at the Z80 on that board. Both  AY-3-8910 chips need to be verified good, and theres a DAC also that plays back the digitized voice sounds. I'd make sure the audio amp is good as well.

Since there's no sounds at all, its possible that there could be a bad data/address buffer responsible for getting the info to the snd board. If the snd board is not told to execute code, it won't. SAme for no clk, if thats not there, its dead in the water.

Before you send it off for repair, pull and clean the pins on *all* socketed chips, shoot some contact cleaner in the sockets, and work them in/out a couple times. Older boards often develop problems with bad connections in the sockets, so thats always the first thing to try.

[matsadona]

Thanks for your tips.
I have just ordered a second board, so that gives me time to check the first one later.
I have also ordered new Z80 and Yamaha chips that I will replace and see if that makes it better.

Just got a Flying Shark board with messed up textures so I'll be busy for a while troubleshooting that one too Maybe there will be an additional thread covering that progress later...