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iTRDC2

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Hello guys,

I have a Neo Geo MV1B that has no sound at all.

Some troubleshooting that I did so far:
  • 1K Potentiometer is OK;
  • Measured the capacitors and all seem to be OK.
Can anyone guide me for further steps on the troubleshooting?

Thank you,
Best Regards,
iTRDC2.
 
No sound could mean a bad amp, bad Z80, bad sound RAM
Bad NEO-C1, broken traces, bad YM2610, etc.
Hi @xodaraP, @Apocalypse

YM2610 is good since on MV1B model it is located on the game socket board and I know that the game socket board is good (because I have a spare working MV1B and tested the socket board of the working board on my faulty MV1B and I have also no sound).

Looked for broken traces and did not found any.

What are the other more commun Issues on this model?
Bad amp, bad sound RAM, bad Neo C1?

Bad Z80 does not seem because I don't get any error on the board boot process.

Neomasta with Unibios won't catch any sound related error, correct?

Thank you Guys,
Ser_opel
 
If you have a spare MVS cart with a ZMC chip you can burn a DiagRom on a (27C001), replace the M1 on the CHA board with the DiagRom and check for z80 errors in depth.

You also need to burn a separate DiagRom file (Sp1) on a 27C1024 and use instead of your current bios.
Details are here:
http://smkdan.eludevisibility.org/neo/diag/


I'm currently making a cart for this purpose. I am also having sound issues with my MVS boards.
 
If you have a spare MVS cart with a ZMC chip you can burn a DiagRom on a (27C001), replace the M1 on the CHA board with the DiagRom and check for z80 errors in depth.

You also need to burn a separate DiagRom file (Sp1) on a 27C1024 and use instead of your current bios.
Details are here:
http://smkdan.eludevisibility.org/neo/diag/


I'm currently making a cart for this purpose. I am also having sound issues with my MVS boards.
Hello @TobyRieper,

I already have a NeoDIAG BIOS and also a DIAG MVS cart that I built (that is needed for the Z80 tests).

I have to install my Neobiosmasta on my MV1B that has the sound ISSUE.
The problem is that I doubt that I will get any kind of error because I don't get any kind of error message when the boards boots with the official bios.

Sound ISSUEs (related with AMPOPs, Amplifiers, CAPs) are not catched by the NeoDIAG BIOS.
Even a bad NEOC1 i think that is not detected :(.

Best Regards,
iTRDC2
 
Hi @iTRDC2 . Glad you have the Diag cart already. :)

Ok so have you checked the Power Amp HA13001? Probe pins 7, and 12 with a multimeter. They are the outputs, you should get a voltage reading. Around 6-12v if I recall correctly.
 
Last edited:
Hi @iTRDC2 . Glad you have the Diag cart already. :)

Ok so have you checked the Power Amp HA13001? Probe pins 7, and 12 with a multimeter. They are the outputs, you should get a voltage reading. Around 6-12v if I recall correctly.
Hello @TobyRieper,

On the MV1B there is no HA13001 Power Amp. Instead I have aTOSHIBA TA8201AK that is also an audio power amplifier.

It INPUT is pin 1 and OUTPUT is PIN 5 and 7.

Best Regards,
iTRDC2
 
You get any voltage from the output pins? N have you tried replacing the op amps?
Hello @TobyRieper,

I get 4 volts at the input and 5.3 volts at both outputs.
I realy don't understant why I don't have sound because as far as I know the Power Amp is the last active component of the sound chain.

I have not replaced the OpAmp.

Best Regards,
iTRDC2
 
Hello Guys,

No one can help on the sound ISSUE troubleshoot?

All sugestions are welcome.

Thank you,

Best Regards,
iTRDC2.
 
Usually first thing i do with it is:
Check the 6116 ram, pull it off and test it. If the brand is sharp or toshiba, mostly had bad busses.

Do you hear a "click" when the board resets and/or a fuzz sound if you raise up the pot? If you hear white noise then AMP, YM and OPAMP are probably fine.
If you don't hear that, you should use a sound probe to the opamp and check if you got sound coming in/out (all end pins, joined togheter).

If none of this works, than you have a dead z80 (and that's very common), you need to change it.
You are still able to find nos here https://it.aliexpress.com/item/4001120806362.html?spm=2114.13010708.0.0.524a4c4dLLc3Wf

I have repaired nearly 15 of these just by doing that (directly replaing the z80). This is because it was basically used in an inconventional way and also this sop version really suffers from 5V variations
 
Usually first thing i do with it is:
Check the 6116 ram, pull it off and test it. If the brand is sharp or toshiba, mostly had bad busses.

Do you hear a "click" when the board resets and/or a fuzz sound if you raise up the pot? If you hear white noise then AMP, YM and OPAMP are probably fine.
If you don't hear that, you should use a sound probe to the opamp and check if you got sound coming in/out (all end pins, joined togheter).

If none of this works, than you have a dead z80 (and that's very common), you need to change it.
You are still able to find nos here https://it.aliexpress.com/item/4001120806362.html?spm=2114.13010708.0.0.524a4c4dLLc3Wf

I have repaired nearly 15 of these just by doing that (directly replaing the z80). This is because it was basically used in an inconventional way and also this sop version really suffers from 5V variations
Hello @TheDeath,

The 6116 RAM that you mention is the RAM 7 IC DIP 24?
Mine instead of 6116 it is a Sharp LH5116D-10.

When you say to use a sound probe to test the OPAMP, it can be a Logic TTL/CMOS Probe, correct?
I have to test it. I did not tested it yet.

Regarding the Z80 (named CPU 2 on the board) if it is "dead" the error will be detected by a NeoDiag BIOS (with the Neobiosmasta)?

Thank you a lot for your tips.

Best Regards,
iTRDC2
 
The 6116 RAM that you mention is the RAM 7 IC DIP 24?
Mine instead of 6116 it is a Sharp LH5116D-10.
LH5116 is a 6116. The 6116 is the common "family name" for 2kx8bit rams. Example, Toshiba likes to call them TMM2018 but still it's 6116 family, there's many


When you say to use a sound probe to test the OPAMP, it can be a Logic TTL/CMOS Probe, correct?
I have to test it. I did not tested it yet.
No, thats for logic. The sound prob is something else. It's basically composed of speaker+amplifier, you then will pin stuff using the "+" or "audio in" of the amp connected to the speaker.


Regarding the Z80 (named CPU 2 on the board) if it is "dead" the error will be detected by a NeoDiag BIOS (with the Neobiosmasta)?
The diag rom is very usefull but also very generic for z80. To be honest i've never used this feature since it will just tell you that the z80 is errored or dead, but it won't tell you if it's the z80 itself, the ram, the dac or the amp, you have to figure it out by yourself.
 
The 6116 RAM that you mention is the RAM 7 IC DIP 24?
Mine instead of 6116 it is a Sharp LH5116D-10.
LH5116 is a 6116. The 6116 is the common "family name" for 2kx8bit rams. Example, Toshiba likes to call them TMM2018 but still it's 6116 family, there's many

When you say to use a sound probe to test the OPAMP, it can be a Logic TTL/CMOS Probe, correct?
I have to test it. I did not tested it yet.
No, thats for logic. The sound prob is something else. It's basically composed of speaker+amplifier, you then will pin stuff using the "+" or "audio in" of the amp connected to the speaker.

Regarding the Z80 (named CPU 2 on the board) if it is "dead" the error will be detected by a NeoDiag BIOS (with the Neobiosmasta)?
The diag rom is very usefull but also very generic for z80. To be honest i've never used this feature since it will just tell you that the z80 is errored or dead, but it won't tell you if it's the z80 itself, the ram, the dac or the amp, you have to figure it out by yourself.
Hello @TheDeath,

Clarified regarding the SOUND Ram.

Regarding the sound probe, is there any good and cheap :)?

Regarding the NeoDiag you are 100% correct. When is a sound problem it is not precise, does not tell if it is a problem on the amp, DAC, RAM was you stated.

Thank you for the tips.

Best Regards,
iTRDC2
 
Thanks a lot man :thumbsup: .

I found one probe equal to the one at the video on eBay but it is from china. It will take forever to reach my home :(.
You are also using one of those?

Any ideia where I can buy it from for example Europe or china but using a faster shipping that the FREE one?

Best Regards,
iTRDC2
 
Thanks a lot man :thumbsup: .
I found one probe equal to the one at the video on eBay but it is from china. It will take forever to reach my home :(.
You are also using one of those?

Any ideia where I can buy it from for example Europe or china but using a faster shipping that the FREE one?

Best Regards,
iTRDC2
No idea sorry. It's super simple to do, i've made my own.
 
Hello @TheDeath,

I already installed the NeoBiosMasta on my faulty MV1B board (no sound board).
I'm getting Z80 error from the NeoDiag BIOS analysis.

I changed the Z80 and I'm still getting the Z80 error and no sound.

Any ideas?

Thanks in advance,
iTRDC2.
 
What is the exact error the diag bios is giving?
 
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