No sound on AES

Xian Xi

Xian Xi

JammaNationX,
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I picked up an AES 3-5 5v model. Everything works fine as far as picture goes. The guy told me there was no sound and yup there is no sound from both the AV port and the headphone jack.

No broken traces, no corrosion and no missing parts. There is a slight hum when I use the headphones/

What could it be?
 
channelmaniac

channelmaniac

Mr Neo Fix-it
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take a cart apart... trace out the pins from the address AND data lines of the sound program ROM to the edge connector. Then check continuity from those pins on the edge connector to the Z80 CPU.

Fix any bad traces.

Next check pin 22 on the sound program ROM for activity. If no signal then check continuity on the AES board and fix the trace.

If that's not it, replace the Z80 CPU with a Z80A CPU.

RJ
 
Xian Xi

Xian Xi

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Hmmm. If I touch the caps in the sound section I get a hum. I guess I need to open up an AES cart.

What's the best way to open one up?
 
awbacon

awbacon

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Im sure you already checked, but I had this issue w/ Fatal Fury Special when I received it. No sound, no jukebox in unibios.

Dirty cart, cleaned, sound came back. Like I said, you know your NeoGeo stuff, but the problem you describe was what I had, and that was the issue causing it for me

good luck w/ it
 
Xian Xi

Xian Xi

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Ok so.

Pin 22 on the M1 is reading low. Pin 7 on the z80 which is the clock pin is reading both high and low.

I also tried swapping the Z80 with 2 different Z80s and still no sound. I noticed on the board it says Z80B, is there a major difference between an A and B?
 
68k

68k

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The clock input will read high and low, because the clock frequency is a pulse of +5V at a rate of 4 MHz. I'm surprised it picked it up.

Z80A = 4 MHz, Z80B = 6 MHz. Safe to use either one.
 
Last edited:
Xian Xi

Xian Xi

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Did more tracing.

Pin 6 on the Z80 was reading very faint, this pin connects to pin 5 on the AS04 Hex inverter. Pin 5 is the input pin on the hex inverter. If pin 5 reads H then pin 6 (the output) reads L, if pin 5 reads L then Pin 6 reads H.

From the AS04 this is what I got:

1. No sig
2. No sig
3. No sig
4. No sig
5. H/L Faint
6. L Faint
7. L
8. H
9. L
10. H
11. L
12. L
13. No sig
14. H

Could this be the problem?
 
channelmaniac

channelmaniac

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You are going the wrong direction.

Take the pinout of the Z80 and find the address and data lines. Follow them to the cart slot and make sure that the continuity is good. If something isn't connected then you found the problem

If you notice, all the address and data pins are in a row. At this point plug in the cartridge boards without the case cover and check for signals on the sound program ROM chip. If you find a missing signal then you found your problem.
 
Xian Xi

Xian Xi

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Oh I see so not the sound controller chip but the actuall sound roms?
 
Xian Xi

Xian Xi

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Just checked the Z80 and it has 100% continuity to the cart slot on all data and address lines.

Also Sound roms all have 100% signals. None missing.
 
channelmaniac

channelmaniac

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Check the output pins (10 & 11) of the YM3016D D/A converter chip for audio. If you have audio there then the problem is in the pre-amp and amp circuitry.

If you don't then there's a problem in the digital part. The Z80 CPU and the 6116 SRAM are the biggest culprits for that.

RJ
 
Xian Xi

Xian Xi

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Just check pins 10 and 11 and got no audio. But there was a bad trace that connected pin 7 & 8 so I fixed the trace and still no audio. The Z80 is working, I tested it on another AES and the 2 chips I have are fine. So the 6116 then?
 
Xian Xi

Xian Xi

JammaNationX,
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I still need a 6116 300 mil package, where can I buy these?
 
Dion

Dion

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Your sure its not just a bad cap in the sound section?

Sounds similar to the Turbo Express problem.
 
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