Street Fighter 2 Audio issue

[kb0jjn]

I dont think I would get further into troubleshooting until Im able to reproduce the original issue after replacing my z80. Right now, after the new chip, I have zero sound. Before I had sound some of the time so Ive made the issue worse. Im going to check for continuity between pins right now maybe I can find the problem

Did you put in a socket?

If you soldered chip right to the board you should solder one pin then skip a pin or solder a pin on the other side. This gives the chip time to cool in that area and it has a better chance of survival. I could have soldered a chip in my board by now but I am waiting on a socket. I have some z80 chips that work for a bit then fail so I want to test them in this board set.

 

[Lazerhawk]

no i didnt put in a socket. I have one pair that reads 0 I dont see anything touching between these pins

 

[kb0jjn]

no i didnt put in a socket. I have one pair that reads 0 I dont see anything touching between these pins

It could be a solder blob under the chip and that is very hard to see. You might be able to get away with just sucking out the old solder and re-flowing the solder joint on both pins.

What are the two pins? I will check mine and might just go ahead a solder in my chip.

It is a Z80A cpu chip right?

I just checked my z80a cpu chips and none of the adjacent pins show a short (0) ohms. This is out of circuit so this may or may not be the problem. In circuit testing does change things.

If it was me, I would try sucking out the old solder on both of the shorted pins and then re solder them in. Give a bit of time for cooling and don't heat up for more than a sec or sec and a half.

 

[Lazerhawk]

After I cleared the two holes the test results are the same. Im going to get another z80 and this time use a socket. Im guessing I must have damaged the cpu since my 25w iron sucks and I didnt think about alternating between pins on opposite sides of the chip either. Ill give it one more shot and see what happens.

 

[Hewitson]

You really shouldn't be doing board repairs with an iron that isn't temperature regulated, you're likely to do more harm than good.

Anyway, what I do in the rare case I'm soldering an IC directly into a board is keep a finger on the top of the chip. When you feel it getting too hot, give it a rest.

 

[channelmanic]

Sigh...

If you guys had a logic probe with audio tones you could put it on the Yamaha DAC chip and see if there's any digital audio coming into the chip. You'll hear a steady beep beep beep of the clock pulses and a scratchy bit of raw digital data coming in when it should be playing audio.

If you hear that raw data coming in then you have sound coming from the digital section and should concentrate on bad caps, bad op-amps, broken pot, or bad audio amplifier IC (Which is actually pretty rare on CPS1 boards)

Those crazy HA13001 ICs are very resilient and rarely fail.

RJ

 

[kb0jjn]

Bumping an old thread.

I fixed my issue, no sound. Replacing the z80 brought the sound back. I wanted to put in a socket but got tired of looking at it taking up space on the testing station.

Womble>You were right again about the z80 chip and I never would have thought to start
there.

 

[Womble]

Bumping an old thread.

I fixed my issue, no sound. Replacing the z80 brought the sound back. I wanted to put in a socket but got tired of looking at it taking up space on the testing station.

Womble>You were right again about the z80 chip and I never would have thought to start
there.

Dead CPUs are pretty uncommon causes of faults, except on CPS1 boards with Zilog branded Z80s. Legend has it that they used Z80s that were not rated for the speed they were driven at, but on the boards I have had to replace the Z80s on the CPUs were marked as being the current speed.

 

[channelmanic]

This is why you use a logic probe with audio capabilities.

Check the /NMI and other inputs then the outputs on the Yamaha sound chips. You can tell right away if the problem is on the analog side or digital side of the sound section.

RJ