Neo Geo MVS 4 slot problems - sound, capacitors, Chinese bootlegs etc

[Max...]

In my 4 slot it was very randomly losing ALL sound, when switching game - this was only fixed by a hard reset.

I now think this is specifically triggered when switching to a pretty new AliX boot (Money Puzzle exchanger).

So I went through the morning (using only genuine carts) and systematically running one cart only in slot 1 alone then repeated for 2-3-4 in turn each for 30 mins then 2 slots occupied, then 3 and finally all 4 with genuine carts. The 5v was increasingly a little low each time so I upped it to show a true 5v with all four running.

Throughout all this testing everything was perfect so I thought I was sorted but later running with two genuine and two boots it again lost all sound when switching (to MPE).

So back to just running that in slot 1 alone - tried wiggling, then slight pressure on chips - all good throughout, no sound loss.

Currently repeating for slot 2.

Any ideas/help welcome.

FWIW - after a heck of a lot of 'discussion' GPT (sorry!) 'told' me:

• If sound drops system-wide, this strongly indicates:
  • A failing Z80
  • A bad or cracked 74-series logic IC in the audio bus
  • A failing YM2610 or its DAC
  • A failing NVC RAM used for sound
  • Cold solder joints that break when warm

OR:

• our original random sound failures were almost certainly due to 5 V rail sagging below ~4.95 V when a cart was inserted, or minor contact resistance in slots or connectors.
• By slightly raising 5 V, the problem disappeared, and now all four slots are stable under load.

 

[Max...]

Just to update - I've tested the Boot (MPE) alone in slot 1 - 2 - 3 - 4 in turn for a while. Soft resets, wiggling - absolutely no issues or sound loss.

So this is to add to earlier test as above on a genuine cart in slot 1 then 2 then 3 then 4. Each time 30 mins, again all perfect.

Then repeating with two carts. Then 3. Finally 4. All genuine carts. Again zero issues or sound loss.

So although when running with 2 boots/2 genuine the total sound cut out seemed to occur when switching to MPE (Boot) I did also have the other boot (Prehistoric Isle 2) in the system so guess I need to repeat the single cart test with this cart too.

But if that runs fine in all slots what next?

 

[Max...]

Any help anyone ?

I have tested every combo of slot and cart and still it seems totally random - and given that I have now separated the two boards and running the sound test on the lower board it is still failing this must be an issue (from what I can gather) with the HA13001 sound amp IC or perhaps the Z80? And nothing to do with slot issues or cart/bootleg issues?

Running just the lower board sound test - when the sound died I was then getting some hissing/crackling.

Following a power on/off sound did not come back. But repeating after a short while it did. And then pressure on the two chips caused no issue.

Board is really clean, all traces look good and no suspect/dry solder joints I can see.

Again AFAIK if the sound is either on or totally off this rules out the caps?

Should I just replace the HA13001 and Z80 to rule them out?

Help!

 

[TheDaddy]

I wpuld recap first myself.

Dave.

 

[Max...]

I was waiting for that Dave! 😂

I have heard it’s a real bugger on these though with SNK’s ‘concrete’ solder on the caps…?

 

[TheDaddy]

Yeh its a sodding nightmare ! lol. So hard to get the buggers out , I have done a few of them and they are doable. If it was a 1 slot I would say just replace it as cheap but the 4 slots are not cheap !

Dave.

 

[Max...]

Hence me copping out with the Z80/HA13001 option first! It’s a beautifully clean board though so deserves a recap but I might just have to dig the two slot out and think about it…

 

[TheDaddy]

Really worth doing , It not that hard really just time consuming and can be hard to remove solder. You may lose the odd track but it is what it is ! Only other tip is replace them all , If one failing they all the same age so just do the lot.

Dave.

 

[Max...]

Well, here is the weirdest thing. Tried my MVS 2 slot board which has always been fine. Put in the 2 boots - MPE + PI2. And the very same thing was happening on the 2 slot, random audio cutting out.

So, there must be an issue with these Chinese boots.

But there must simultaneously still be an issue with the previously fine 4 slot as it fails the sound test randomly when running the lower board only.

Can these boots f%%k up the hardware??

 

[Retroman839]

Well, here is the weirdest thing. Tried my MVS 2 slot board which has always been fine. Put in the 2 boots - MPE + PI2. And the very same thing was happening on the 2 slot, random audio cutting out.

So, there must be an issue with these Chinese boots.

But there must simultaneously still be an issue with the previously fine 4 slot as it fails the sound test randomly when running the lower board only.

Can these boots f%%k up the hardware??

I was going to say that ..
It’s just bootlegs mvs for you.

Since Ali express they have been manafacturing for the extra reach the Ali express selling platform has aroumd
The world .. these carts seem to be hit a miss regarding developing a fault for obvious reasons.

Having said this the connectivity regarding the metal used on the finger edge board may not be as good ,
But try cleaning cart gold finger board , and you mvs slots
But if all you originals work fine as you say ,
It’s most likely just the boot legs have a hardware issue or maybe they ripped / compressed sound files to fit the game on the rom they used . Unfotuantly they do do that .

 

[thegreathopper]

Yes agreed, boots seem to cause issues like this.

 

[Max...]

Thanks guys, the MPE I got new last year and PI2 brand new this month - yes, both AliX specials.

I cannot remember any issues before with the sound using MPE so it must be the PI2 that I threw into the mix this week.

I have very thoroughly cleaned all the slots and every game I'm testing.

I have a few much older BITD boots and they have been fine.

But whether it is coincidence or not - it is odd that NO carts in - the sound test on the 4 slot is also failing so there must still be a hardware issue.

 

[Retroman839]

Thanks guys, the MPE I got new last year and PI2 brand new this month - yes, both AliX specials.

I cannot remember any issues before with the sound using MPE so it must be the PI2 that I threw into the mix this week.

I have very thoroughly cleaned all the slots and every game I'm testing.

I have a few much older BITD boots and they have been fine.

But whether it is coincidence or not - it is odd that NO carts in - the sound test on the 4 slot is also failing so there must still be a hardware issue.

Yeh the oldies are the goldies

You can do returns on Ali
Respect to that
Because I have done it and true enough I got refunded
Re purchased item
Replacement arrived and was fine ..

I think the quality control
Is you buy it See if it works.
🤣

I have some friends that have product manafactired in China
And you can choose which Safty certificate / sustainably sourced materials labels you want on the box.

 

[Max...]

Yes, will do a return on this - use AliX a lot and on the whole it's pretty unbelievable service - I've had stuff frequently now in 5 - 7 day, free shipping, no hassle at all on lots of returns. I've tired to capture the sound on PI2 going as they like a video but it's so random...

Back to the 4 slot though, I have captured this on video this morning running the sound test. I left it on and the sound has gone completely now so just a little hiss/crackle.

I guess this means re-cap time or should I still look at the Z80 and HA13001 too?

 

[Retroman839]

How is the traces around battery area ?

I repaired a 4 slot for someone recently same symptoms ..

It was the traces from battery leak

 

[TheDaddy]

The sound may go off on Boots but it should not damage the PCB itself , Well as far as I know anyways. I would test with the 2 Boots in only.

" I guess this means re-cap time or should I still look at the Z80 and HA13001 too? " - With audio issues I follow a bot of a flow chart and basically is I have sound and its there then goes or quiet then the first this I do is recap the board. I do check the Amp and stuff around make sure nothing obvious. Audio issues can be an absolute pain in the arse to track , I have a Superman somewhere I also snapped in half after spending so long on it and getting frustrated as I replaced everything and still wont work !

Good Luck !

Dave.

 

[Retroman839]

Analogue sound use a phil mur sound probe
Digital pita !

 

[Max...]

Traces all good - I did an off-PCB battery mod years ago.

Board overall is lovely, really lovely so I'd like to keep it going.

Sitting here sound just kicked back in - crackle/beep/crack! then off again...

 

[Retroman839]

Traces all good - I did an off-PCB battery mod years ago.

Board overall is lovely, really lovely so I'd like to keep it going.

Sitting here sound just kicked back in - crackle/beep/crack! then off again...

Does sound like caps or amp

 

[Max...]

Analogue sound use a phil mur sound probe
Digital pita !

TBH probing and all that is past my pay grade, I can do basic modding, consolizing, making leads and Jamma harnesses etc but once you delve deeper I'm lost!