What's new
By:
Filters

MV2F No Game Sound - Help

A

ArcadeBattler

Beginner
Joined
Apr 29, 2022
Messages
19
Reaction score
8
Location
Canada
Hello,

I have a 2 slot MVS board which I need help getting sound working again.

Currently, sound within the test menu works no problem, but I can't get sound from any cartridges.

I have already:

-recapped the board
-swapped the z80
-swapped the bios

I have the following tools available to me:

-soldering station/smd rework station
-multimeter
-logic probe
-Oscilloscope

Any help would be greatly appreciated. Furthermore if chip locations/pin numbers could be included in suggestion that would greatly help, as I have never repaired a neo geo before and I am not fully confident in what is what.

Thanks!
 
Is the battery still working? Have you cleared the backup ram?
 
When you do the bios sound test its running code on the z80 from the SM1 rom on the motherboard. When you are booted to a game the sound code comes from the M1 rom on the games CHA board. You likely have some data/address issue between the cards M1 and the Z80 cpu, which would cause the Z80 to crash.

The data line path from the carts should be going to the NEO-257 near the Z80 cpu. The NEO-257 will pass along the data lines to the Z80 for which ever slot is active (if any). I don't recall what the address line path is off the top of my head, but would guess there is an IC between the address lines and the Z80.

Using a stock bios (unibios will be bugged for this test), boot with only a cart in slot 1, see if sound works for the game. Then do the same test but only a cart in slot 2.

- If one slot has sound and the other doesn't look for bad continuity between the slot and those NEO-257 and/or the address line IC.
- If neither slot has no sound, look for an issue between the NEO-257 and/or address line IC to the Z80. It also possible one of those ICs is bad.
 
ack said:
When you do the bios sound test its running code on the z80 from the SM1 rom on the motherboard. When you are booted to a game the sound code comes from the M1 rom on the games CHA board. You likely have some data/address issue between the cards M1 and the Z80 cpu, which would cause the Z80 to crash.

The data line path from the carts should be going to the NEO-257 near the Z80 cpu. The NEO-257 will pass along the data lines to the Z80 for which ever slot is active (if any). I don't recall what the address line path is off the top of my head, but would guess there is an IC between the address lines and the Z80.

Using a stock bios (unibios will be bugged for this test), boot with only a cart in slot 1, see if sound works for the game. Then do the same test but only a cart in slot 2.

- If one slot has sound and the other doesn't look for bad continuity between the slot and those NEO-257 and/or the address line IC.
- If neither slot has no sound, look for an issue between the NEO-257 and/or address line IC to the Z80. It also possible one of those ICs is bad.
Click to expand...
Would you be able to give me your best guess on which chip I should look at based on the grid on the board?
 

Attachments

  • neo-geo-mvs-slot-jamma-arcade-circuit_1_94242921b650c0155423a3cd02a56646.jpg
    neo-geo-mvs-slot-jamma-arcade-circuit_1_94242921b650c0155423a3cd02a56646.jpg
    202.5 KB · Views: 46
The NEO-257 is at J11. The address lines likely got through that NEO-E0 at L11.
 
ack said:
The NEO-257 is at J11. The address lines likely got through that NEO-E0 at L11.
Click to expand...
I've replaced the neo-e0,g0,d0 all around that area, and I cant seem to find any broken traces. Do you have any other suggestions?
 
ArcadeBattler said:
Would you be able to give me your best guess on which chip I should look at based on the grid on the board?
Click to expand...
Any pictures of your actual board? I fixed a 2 slot this afternoon. Wasn't booting at all, cleaned up some solder splatter all over, a few pins touching that shouldn't, and booted up. After that it worked but had no sound and it was just missing a couple components (a film capacitor and an electrolytic).
 
You must log in or register to reply here.
Back
Top