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MVS 2 Slot No Sound

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ArcadeBattler

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Hello everyone,

I have a MV2F that is not producing any game sounds. I have recapped it, and the internal sound test is working.

Any suggestions would be appreciated!
 
Last edited:
use a scope or audio amplifier to check the audio coming from the sound chip - then trace it through the op-amps till you lose it
do you hear any hum with the sound turned up?
if not - check the volume pot and the amp chip
 
stj said:
use a scope or audio amplifier to check the audio coming from the sound chip - then trace it through the op-amps till you lose it
do you hear any hum with the sound turned up?
if not - check the volume pot and the amp chip
Click to expand...
Hey,

there is hum coming through the speakers with the sound turned up (it actually picks up and amplifies a radio station if I touch the caps for some reason), there is just no sound coming from the cartridges. Do you know which pins on the sound chip I should check?
 
no, but you can download the schematics.
my bet is a bad op-amp.
 
Try to reset ram by flipping all dip switch on, booting to ram test then going back to normal.
Some backup ram corruption results in sound being off.

You said sound test is working, so I suppose not only menu work but you also hear the beep note.

If so, this mean the audio section mostly work and only switching to cart M1 rom is causing trouble. Check continuity between m1 rom and z80. Also check the g0/e0 that connect to it. A broken neo-g0 seems probable.

Also, be aware that with unibios 4.0 the sound works in slot2/3/4/5/6 only if a cart is ok in slot 1.
 
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Rom1 said:
Try to reset ram by flipping all dip switch on, booting to ram test then going back to normal.
Some backup ram corruption results in sound being off.

You said sound test is working, so I suppose not only menu work but you also hear the beep note.

If so, this mean the audio section mostly work and only switching to cart M1 rom is causing trouble. Check continuity between m1 rom and z80. Also check the g0/e0 that connect to it. A broken neo-g0 seems probable.

Also, be aware that with unibios 4.0 the sound works in slot2/3/4/5/6 only if a cart is ok in slot 1.
Click to expand...
Hey thanks for the reply,

would you happen to know which pins I need to check, I'm trying to find it on the dev wiki but I'm getting a little lost.
 
Update,

I replaced the neo-257, neo-g0, and neo-e0 at locations k-10, k-9, and j-9 since I had some I was able to salvage. No improvement doing that, idk if this info helps at all.
 
On the 2 slot boards... if Backup RAM gets corrupted it can do that odd thing where you hear the beep in test mode but no audio from games. Reset the Backup RAM and try again.

Next, if you have bad continuity between the slots and the NEO-G0 or NEO-257 chips over by the sound CPU then you won't have sound in games. Those chips buffer the address and latch the data lines coming from the 2 slots wiht the latter chip (257) choosing which slot to receive the data from. Without full connectivity to the M1 ROM on the cartridge slots you have no audio as the audio CPU crashes. You get the audio test beeps from the ROM in the sound section which runs until you plug a cart in then the cart ROM takes over.

I'd start with looking up the cartridge slot pinout and checking continuity for the address lines to the sound ROM on the carts. Those are common between both slots.
 
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