Smsfm woes.

[mvsfan]

I just installed an smsfm kit in my master system. The instructions for the small sheilded wire werent that clear and i think i got the red and white wire backwards. Now all i get is a loud buzzing out of the master system.

I think i blew the sound leg on the z80, but i have 2 questions about it.

Is the z80 in the Genesis exactly the same? would it work fine in my master system? I have a small stack of spare genesis consoles here.

I think i know how to test the z80. IF i hook a powered speaker up to the sound leg i should hear sound out of it if its working.

also how would i know that its not one of the chips on the smsfm kit?

[mikejmoffitt]

I just installed an smsfm kit in my master system. The instructions for the small sheilded wire werent that clear and i think i got the red and white wire backwards. Now all i get is a loud buzzing out of the master system.

I think i blew the sound leg on the z80, but i have 2 questions about it.

Is the z80 in the Genesis exactly the same? would it work fine in my master system? I have a small stack of spare genesis consoles here.

I think i know how to test the z80. IF i hook a powered speaker up to the sound leg i should hear sound out of it if its working.

also how would i know that its not one of the chips on the smsfm kit?

I do not know of any Z80 with sound coming out of the CPU. You may be thinking of the NES's 2A03, or a VDP with integrated audio.

I would just source a Z80A and install one if you suspect the CPU is the issue.

[mvsfan]

well, according to the service manual i was looking at for the master system model 1, one of the pins of the z80 is labeled sound i didnt see anything else in the diagram labeled as sound.

[mvsfan]

I found some more information on a different website. looks like the sega SN76489 is actually the sound chip.

[BONKERS]

I found some more information on a different website. looks like the sega SN76489 is actually the sound chip.

Yes, that's the PSG chip. Which is what actually produces the sound. However, it's probably routed and buffered to a DAC before output or something.

The Z80 Sound line is probably just for the sound logic to communicate to the PSG chip. I would only tap the actual line level output lines.

[ApolloBoy]

Actually the SMS doesn't have a discrete sound chip, it's integrated with the VDP.