Jungle King background audio issue

MajorHavoc

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I have a friend's JK boardset that works except for the background audio has an issue. The first ~8 seconds of the background tune just holds a single note. After that the background audio seems normal (and all event specific audio seems OK).

I have swapped all the chips (except EPROMs) from a 100% working JH board with no change. Any ideas what to check next?

Thanks!
 
You have friends? Hey, coming to the party on the 2nd?
Its a long shot but have you tried swapping the ribbon cables out?
 
There are four sound chips on the top board.

Have you tried swapping those around? One of them may be for handling the I/O though. The sound ROMS are the three at the bottom left of the top board.

OK- I just looked- the three chips at the bottom above the Z80 are for the different sound channels. There is a lot of mixing going on and some control signals coming from the game board, so almost anything could be going on.

With the lack of a nice test feature, it's hard to troubleshoot.

Good luck- post your results.

K
 
You have friends?

No. But I pretend Darryl is my friend even though I am just one of his many KLOV repair bitches! :)

Hey, coming to the party on the 2nd?

First I have heard about it (I am really irregular on KLOV) but SURE! Just need to check with calendar first ...

Its a long shot but have you tried swapping the ribbon cables out?

Good idea! Unfortunately the cables are soldered to the video board but it would be a good idea to ensure that the problem is actually on the game board (which has the audio).

Thanks!
 
Strange! The problem is being caused by the CPU PC board (bottom of the stack)! I swapped out all the RAM and the CPU on that board with no change. I'll swap out the EPROMs next ...

Any good troubleshooting sites for these Taito board sets? Or has anyone cooked up a test ROM?


There are four sound chips on the top board.

Have you tried swapping those around? One of them may be for handling the I/O though. The sound ROMS are the three at the bottom left of the top board.

OK- I just looked- the three chips at the bottom above the Z80 are for the different sound channels. There is a lot of mixing going on and some control signals coming from the game board, so almost anything could be going on.

With the lack of a nice test feature, it's hard to troubleshoot.

Good luck- post your results.

K
 
The problem was a bad EPROM, KN60, the EPROM right next to the CPU on the CPU (bottom) board.

I loaded this bad EPROM into MAME and it replicates the error in MAME. Cool! :)
 
The audio board has 5 test spots (they are just enlarged solder spots, no hardware attached so it is hard to find/use them).

PSG0: Background music
PSG1: Jump & Fall
PSG2: Tarzan yell & Thud (when you hit the ground)
PSG3: ?
PSG4: Vine swinging
 
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