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NBA Jam pcb


Jamie
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I picked up a Williams NBA jam pcb that seems to have issues. I connected the ribbon cable and plugged it in and it ran through rom test successfully and played all be it without sound. Tried again and it just didn’t start at all. Then after starting re starting a few times it started up again. Now currently not starting. Occasionally but very seldomly I see some activity on the screen nothing like a picture though. Could this be a ribbon cable it wasn’t connected when I got the boards and they aren’t attached to each other only by ribbon cable. Any ideas about this and where would the best place be to have it repaired if required??

 

Thanks.

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Thanks Boots, it was a problem with power supply and i could measure that on the power supply itsef. I have a 500 in 1 Game Wizard that it didn't seem to effect so this through me. I changed the power supply witu a new one but it come up with the same voltages. Not real sure why that it. Anyway, a problem for another day maybe.

 

What i would appreciate some help with is a sound issue. It has no sound. Rom chevk all good. Cab and spewker good. I checked schematic and can see that i have a connector that isn't attached to anything appears to go in P3 on the cpu from P6&7 on the sound board. Would be obvious i guess if my sound board connector was a 9 pin like the cpu instead it is an 8pin connector so maybe just what was available to the tec at the time.

Also, i only have one ground wire connected to the two boards ( sound and cpu). Is that an issue??

I think iam getting onto this but wanted to check with pros before i go plugging shit in.

 

Please help, NBA Jam without sound sucks.

 

Cheers.

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Iam pretty sure I need to connect these two boards with as mentioned above but Iam really not sure if the missing ground wire is an issue. I would hate to stuff this nba up. I’ve been so keen to get one. Is there anyone that might be able to assist with this?
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Hey Jamie,

 

The connector you mentioned does need to be connected to P3 on the mainboard. Your picture was a bit hard to see but it looks like the red wire in the connector is next to a black wire and then there is a blank pin or two. If that is the case then that end of then connector should be nearest to the P4 plug end of the board. My connector has 5 wires in a row, then blanks, then the 2 wires on the end.

 

On the sound board it looks like you have a plug connected to P5 but it doesn't appear to have any wires connected to it. There should be wires connected to pin 2 and 4 that run to a potentiometer . Without this connected you won't get any sound. I've included a pic of my board. All the wires are red though, so it's a bit hard to make sense of!

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