Zero Wing: NO sound

kb0jjn

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I have a guy who set me a message trough e-bay and somehow he knew I buy mostly NON working boards and ask me for some help.

He has a sound problem, lack of any. The game plays fine. After looking at some pics of the board I recommended replacing the caps in the area of the amp. The amp is good, he can run his finger across the pins and get noise. I look further down and I see my favorite Zilog z80 chip. I told him I would send him a replacement to see if that is the problem.

If that is not the problem where else can I have him look at? I am thinking the Yahama chip or the supporting chips.
 

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This is where I'd take the logic probe and see if there are any digital audio pulses going into that 8 pin DAC that mates to the Yamaha sound chip. If there are none then I'd start with the digital side of the circuit.

If there are then I'd recap first then go after the op-amps 2nd.

I hate those radial caps that are branded TK. They are the crappy ones SNK used a ton of on the Neo Geo boards.
 
This is where I'd take the logic probe and see if there are any digital audio pulses going into that 8 pin DAC that mates to the Yamaha sound chip. If there are none then I'd start with the digital side of the circuit.

If there are then I'd recap first then go after the op-amps 2nd.

I hate those radial caps that are branded TK. They are the crappy ones SNK used a ton of on the Neo Geo boards.

You Were Right....AGAIN.....Here is the response I got form Canada today....


Hi guys,
I have monitored 8-pin DAC ym3014B with Scope, there is a digital signal in but no audio signal out to the Pre-amplifier IC LM358N.
Most likely the DAC is dead. Do you have a new replacement part?
K C

K C is The tech on the other end.
 
Zilog Z80s are not a common cause of failure and dont need to be replaced on sight unless it is a CPS1 board with missing audio. Have never seen a bad Zilog Z80 on any other board.

Get your contact to check the DAC is getting its clock on pin 5, no clock = no DAC'ing.
 
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You Were Right....AGAIN.....Here is the response I got form Canada today....


Hi guys,
I have monitored 8-pin DAC ym3014B with Scope, there is a digital signal in but no audio signal out to the Pre-amplifier IC LM358N.
Most likely the DAC is dead. Do you have a new replacement part?
K C

K C is The tech on the other end.

Now before you proclaim the DAC dead please keep in mind that the DAC will have a steady set of clocking pulses going to it. When the audio appears the pulses on the input pin will not be steady and will be a digital representation of the sounds that should be coming out of the DAC. Constant steady = no audio coming into the DAC.
 
Now before you proclaim the DAC dead please keep in mind that the DAC will have a steady set of clocking pulses going to it. When the audio appears the pulses on the input pin will not be steady and will be a digital representation of the sounds that should be coming out of the DAC. Constant steady = no audio coming into the DAC.

It is true...Great minds do think alike.....

Sent: Tuesday, January 31, 2012 9:15 AM
Subject: Re: Fwd: PCB

System clock & Serial Input digital signal are present at its terminal but there is no audio signal at the output "TO BUFFER".
Pretty sure the DAC is dead.
K C


On 1/30/2012 7:05 PM, William Harshman wrote:
> Trying to find a source for that part to justify the cost of shipping as I need several parts myself. Have K.C. check for "clock" signals on that DAC. If all clock signals are there then the DAC is bad. I will have some kind of answer for you in about a day or two.
>

EDIT: This is the only source I have found for the DAC I have found so far

http://www.andysarcade.net/store/index.php?act=viewProd&productId=1386
 
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Andy is a good bloke.

I have a bunch somewhere, just buried on anti-static foam and no time to test.

Do you have an old revision 1 Sega Genesis laying around? IIRC, there's one on it.
 
Andy is a good bloke.

I have a bunch somewhere, just buried on anti-static foam and no time to test.

Do you have an old revision 1 Sega Genesis laying around? IIRC, there's one on it.

I have one here but the 8 year old doesn't want me to take it apart and I don't have a rework station yet. I would probably ruin it removing it.

If you can send one to him I will make good on the payment and shipping.
 
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Let me dig and see if I can pull one out of chip storage. It may be Friday/Saturday.

PM me the address. It shouldn't be out on the public forum.
 
To put an end to this thread; this is the response I got from the tech in Canada:

Hi Tony,
The game board is back to sound after replacing the DAC
As usual, I'll put it in my porch area tomorrow. Please come to pick it back.
Have fun.
K C
 
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