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MV1FZ sound error [Solved / Neo-C1]

Retro Mecano

Retro Mecano

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Hello,

My MF1z plays games fine, except for sound when starting the playgame. Menu is ok, character select is ok, but when after selection i can hear the starting neogeo logo. In addition starting the level will stop the music and sounds. Exactly at the same position every time.

I got with diag rom and cart the exact same error everytime. z80 dead.
Excpexted :3C
Actual:4C

1000006219.jpg

Tested all continuity between Z80, Ym2610, Sm1, D0, C1 and cart port pins.

Changed z80 anyway, 6116 and checked the sm1 rom. No change.

1 year ago, Board already recapped, a0 amp changed and battery removed. Worked like a charme

What to see next?
 
Are you using a cart with the diag m1 rom on it?
 
The version I pointed at is newer.

Anyways, Both sides (68k cpu and z80 cpu) are complaining about bad communication with the other. That communication is mostly handled by the NEO-C1 and NEO-D0.

https://wiki.neogeodev.org/index.php?title=NEO-C1

On the NEO-C1 I would check the SD0-SD7 pins going to the z80 and D8-D15 going to the 68k cpu. The 3x SDZ* pins which should come from the NEO-D0.

https://wiki.neogeodev.org/index.php?title=NEO-D0

On the NEO-D0 I would check SDW (comes from NEO-C1) and NMI going Z80. MREQ and IORQ pins which should be coming from the z80.
 
ack said:
The version I pointed at is newer.

Anyways, Both sides (68k cpu and z80 cpu) are complaining about bad communication with the other. That communication is mostly handled by the NEO-C1 and NEO-D0.

https://wiki.neogeodev.org/index.php?title=NEO-C1

On the NEO-C1 I would check the SD0-SD7 pins going to the z80 and D8-D15 going to the 68k cpu. The 3x SDZ* pins which should come from the NEO-D0.

https://wiki.neogeodev.org/index.php?title=NEO-D0

On the NEO-D0 I would check SDW (comes from NEO-C1) and NMI going Z80. MREQ and IORQ pins which should be coming from the z80.
Click to expand...
I Made a new burn with the link you shared, and i got this message (same prrrt sound, and 001100 beep) only thing changed is "excpected" is 3C. Was 4C before.
20250115_191511.jpg

Checked also all continuity you mentionned. All ok.
 
There are some details of how the comm test works here

https://github.com/jwestfall69/neogeo-diag-bios/blob/master/docs/tests/comm_test.md

But the gist of it is

Code: 
   1. bios: wait for HELLO (0xc3) message
   2. m1 -> bios: send HELLO (0xc3) message
   3. bios: accept HELLO (0xc3) message
   4. bios -> m1: send HANDSHAKE (0x5a)
   5. m1: accept HANDSHAKE (0x5a)
   6. m1 -> bios: send ACK (0x3c)
   7. bios: accept ACK (0x3c) message
   8. m1: test clearing the receive data port

Your picture implies the path from m1 -> diag is working ok because diag bios got the 0xc3/HELLO message and sent back the 0x5a/HANDSHAKE to the diag m1. However it would appear the diag m1 never got that message. The sound latch (in the NEO-C1) should get updated when the 68k writes a byte to address 0x320000. I would try checking the following on the NEO-C1

A17-A21 should go to the 68k cpu
A22I-A23I devwiki says those go to a NEO-E0
R/W, UDS, LDS, AS, DTACK should go to the 68k cpu

On the NEO-E0

https://wiki.neogeodev.org/index.php?title=NEO-E0

A22-A23 should go to the 68k cpu

Its of course possible you have a faulty NEO-C1 or something else.
 
ack said:
There are some details of how the comm test works here

https://github.com/jwestfall69/neogeo-diag-bios/blob/master/docs/tests/comm_test.md

But the gist of it is

Code: 
   1. bios: wait for HELLO (0xc3) message
   2. m1 -> bios: send HELLO (0xc3) message
   3. bios: accept HELLO (0xc3) message
   4. bios -> m1: send HANDSHAKE (0x5a)
   5. m1: accept HANDSHAKE (0x5a)
   6. m1 -> bios: send ACK (0x3c)
   7. bios: accept ACK (0x3c) message
   8. m1: test clearing the receive data port

Your picture implies the path from m1 -> diag is working ok because diag bios got the 0xc3/HELLO message and sent back the 0x5a/HANDSHAKE to the diag m1. However it would appear the diag m1 never got that message. The sound latch (in the NEO-C1) should get updated when the 68k writes a byte to address 0x320000. I would try checking the following on the NEO-C1

A17-A21 should go to the 68k cpu
A22I-A23I devwiki says those go to a NEO-E0
R/W, UDS, LDS, AS, DTACK should go to the 68k cpu

On the NEO-E0

https://wiki.neogeodev.org/index.php?title=NEO-E0

A22-A23 should go to the 68k cpu

Its of course possible you have a faulty NEO-C1 or something else.
Click to expand...
Just rechecked all of that.. all connections are like described..

Not sure how to feel about it lol.

Noticed one thing, start+select does not work in diag bios. They work fine in unibios 4 to soft reset.
 
Retro Mecano said:
Noticed one thing, start+select does not work in diag bios. They work fine in unibios 4 to soft reset.
Click to expand...
This is usually caused by your supergun/cabinet having the select button wired to insert coin instead of select.
 
ack said:
This is usually caused by your supergun/cabinet having the select button wired to insert coin instead of select.
Click to expand...
So anyways, after all these checks, is it a verdict Neo C1 is failing, or still a chance another minor component is out?

The fail is confusing me because the slot is absolutly not heavily used. May be played once a month for 1 or 2h..
 
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