Help with SF2 World Warrior w/ no sound.

mustang_5l

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Ok so here's the skinny...

I have a Street Fighter 2 World Warrior Jamma PCB and I get no sound. Game plays fine and acts the way it should... except no sound.
Checked all the dips and adjusted the pot - no sound.
Cleaned the terminals - no sound.
Adjusting the pot yields nothing at all, not even a crackle in the speakers, not even a hum.

I switched out the (C - Bottom ~ sound board) with a friends copy of this game and the game now plays with sound... So its not the A-top or B-Middle boards. (Mine top two boards work fine on his bottom board too)

The problem lies in the the bottom board somewhere.

Suggestions? Should I just replace the 8 caps around the sound pot then the sound pot itself and see where that leads me?
I have a logic probe - although I've never used one... and a good multi-meter at my disposal.
Where should I start and look first?
Please help me sort this out...
John
 
The A board is the bottom board. The small board on top is the C board.

Test the pot with a multimeter. If it checks out, then touch the pins of the amp and see if you get static through the speakers. If not, the amp has failed or the capacitors associated with it are faulty.
 
Edited thanks for the heads up:
I switched out the (A - Bottom ~ sound board) with a friends copy of this game and the game now plays with sound... So its not the C-top or B-Middle boards. (My top two boards work fine on his bottom board too)

I will check pot - how much resistance should I be reading?
 
Capcom used a lower rated Z-80 on those motherboards that is prone to failure. The "A" board overdrives the Z-80 leading it to just give up. If your amplifier checks out good then that is what will most likely be the problem.

You can replace it with a faster Z-80A and the board will work perfectly (if that is what has failed :p)

Brian.
 
could you point me in the direction of where the z80 chip is located on the A-board? And any schematics that are available? Been looking & can't find anything.
 
could you point me in the direction of where the z80 chip is located on the A-board? And any schematics that are available? Been looking & can't find anything.

Never-mind... I was staring right at it. :p

No how do I test the bloody thing?
It is a Zilog Z0840004PSC SL0965 Z80CPU 9214 ZY
 
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I ran my fingers across the sound amp pins while the game was "playing". I got a humming noise towards one side (north-up) of the pins. Nothing towards the bottom-south part of the board. The noise increased and decreased with the adjustment of the pot.
Still no music or game sounds.
 
Sounds to me like you have an "A" board with a bad Z80 chip.

If you have a CPS1 parts board handy, with working sound: Remove a Z80 chip from a parts board (or source a working Z80 chip elsewhere). Then remore the Z80 chip from the SF "A" board. Next, put a socket on the "A" board. And, then put the replacement Z80 in the socket. Re-test the game: See if sound works.

The Z80 chips CAPCOM used on the "A" boards have a high rate of failure.
 
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Thanks for the advice... Just removed my first Z80 chip... took my time (4 hrs) because this is the first thing I've ever DE-soldered anything. Not going to get rich ever fixing these things! That was a chore... using de-soldering braid and sucker to finish off. I'm putting a socket in now.

Praying this works!

Who sells the Z80 replacement chips?
 
Who sells the Z80 replacement chips?

I know Channelmanic sells them on his site, www.arcadecomponents.com. So do several others here in the forums (not trying to leave anyone out, RJ's is just the first one that come to mind).

Alternatively you could just search for "z80 cpu" on Ebay.... I just did and came up with 143 results ranging in price from $3.00 to $24.00 (not including shipping).

You will also want to get a socket for it so you can more easily replace it if it ever fails again.

Brian.
 
You've never desoldered anything, yet you managed to remove a Z80? Very impressive, I couldn't do that with solder wick and a sucker.

Yeah... like it says... 4 hours! Being very meticulous.
Looks like a Final fight board I have may have the same issue :(
Got a whole bunch of sockets to install now :$

Might just cut the chip legs next time then de-solder by pulling the legs through with some tweezers. Damn... should have read deeper in the klov archives for that one... ouch!
 
Might just cut the chip legs next time then de-solder by pulling the legs through with some tweezers. Damn... should have read deeper in the klov archives for that one... ouch!
That's the method I'd recommend. However if you plan on doing a bit of desoldering in the future you might want to consider getting a Hakko 808 desoldering gun, or even a 472D desoldering station, which is what I use.
 
That's the method I'd recommend. However if you plan on doing a bit of desoldering in the future you might want to consider getting a Hakko 808 desoldering gun, or even a 472D desoldering station, which is what I use.

I'm hoping not to do this as an ongoing thing... just to fix my personal stuff.
a $4.00 chip vs an expensive tool... $4.00 chip wins the old one dies!
 
Thanks for the advice... Just removed my first Z80 chip... took my time (4 hrs) because this is the first thing I've ever DE-soldered anything. Not going to get rich ever fixing these things! That was a chore... using de-soldering braid and sucker to finish off. I'm putting a socket in now.

Praying this works!

Who sells the Z80 replacement chips?

Here's a little trick you may not have read yet.... when you're going to desolder a chip, first add a small amount of new solder to the pins. It makes it about twice as easy to remove the old solder, and it tends to come off cleaner.
 
This is where a logic probe with audio capabilities comes in handy. You probe the outputs of the OKI DACs and the inputs/outputs of the Yamaha DAC and listen to the sounds.

If the sounds aren't there then replace the Z80. If the sounds are there, recap the audio section.

I don't think I have any Z80A CPUs in webstock but I do have 'em.
 
If the sounds aren't there then replace the Z80. If the sounds are there, recap the audio section.

I don't think I have any Z80A CPUs in webstock but I do have 'em.

No sounds before I pulled the chip.
I hope you have the Z80A's in stock... I ordered 3 of them from you yesterday online! ;)
 
Just a note here. The best way to remove ICs from a board without a decent desoldering setup is to cut the chip legs at the body, remove the IC, and remove the pins one at a time. Then you can clear the thru holes and install a socket or new chip. Don't forget to deflux the board before installing new parts. Denatured alcohol does a good job.

If you *must* desolder without cutting the pins, liquid flux over the existing solder makes it flow better when heated and will pull out much cleaner with a manual solder sucker. MAkes life easier...
 
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