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NoGoodCitizen

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Hi everyone!

I don't post very often (I'm more of a lurker) because I'd rather read/learn than weigh in with my usually incorrect observations. I have an SFEX2 ZN2 board I inherited from a friend of mine, and it plays great with no issues, except it does not play BGMs. There was a bit of corrosion going on with the socket that EX2-01m was seated in, and that has since been cleaned and replaced, along with a brand new freshly burned EPROM. Still, even after that, I am not getting any BGM, and the board does not fail any checks. I've confirmed that the replaced socket is getting power to all pins by checking with a meter.

I'm at a loss as to what I should be doing next, since there is not a lot of documentation out there on these boards.

Any advice? Please help!
 

ekorz

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If you have another capcom zn2 base you can swap the rom board onto it. That way you can at least see if the issue is romboard or motherboard related.

If it's the motherboard, while I don't think there are schematics out there for zn1/zn2, there are schematics for playstation 1 and those overlap somewhat iirc. The analog sound section is right near the mono/stereo switch and the volume knob, anyway, and if you have an audio probe you could perhaps see if it's an op-amp failing to mix in the bgm or something like that.

Also if you notice any caps missing from the motherboard that could be the issue. They do get knocked off sometimes.
 

NoGoodCitizen

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Thanks Ekorz, I'm going to go ahead and replace the amps at the large heatsink and report back. I appreciate the insight. Cheers
 

ekorz

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I would expect the amp at the heat sync to have the sound mixed already. Somewhere before that is an smd op-amp I think.

But it is just one of many places to check. I wouldn’t shotgun anything before probing it. Especially if you don’t even know if it’s the romboard or the motherboard!
 

ekorz

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Just put mine on a bench. The sop8 right next to the stereo/mono has BGM playing on pins 1 and 7. I’m pretty sure that’s an op amp but I can’t read the chip number on mine. Do you have an audio probe?
 

NoGoodCitizen

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Just put mine on a bench. The sop8 right next to the stereo/mono has BGM playing on pins 1 and 7. I’m pretty sure that’s an op amp but I can’t read the chip number on mine. Do you have an audio probe?
I don't have an audio probe, I suppose I should pick one up..

edit: i actually have one already (in a way) thanks to my old days in IT - I can hear SFX coming through pins 1 and 7, but no BGM :(
 
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NoGoodCitizen

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Is it possible to probe those with the audio probe? I apologize, I'm something of a novice on this topic.
 

Hammy

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Not sure, DAC will be a mix of data and sound, i guess you can check it's output.
 

andersonbiasoto

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troca o qsound, ativa o mesmo problema numa ZN-1
change qsound, I had the same problem on a ZN-1
 

nnap

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Had this issue on a EX2 and it was a dead Z80 on the rom board.
 
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