Is the stereo mod possible on a MV-1ACHX?

Relo

n00b
Joined
Mar 14, 2015
Posts
19
A while ago I got myself a MVS with some hassle (the first 3 cam broken), and wanted to stereo mod it, so I build myself some MV-1X stereo PCB boards.

Seeing as I have a MV-1ACHX board and there being no guides that I could find for it, I based the solder points on on the Jamma Nations guide for the MV-1A and confirmed the points with a multimeter. All fine so far.

So I installed the board, but I got almost no stereo separation only a tiny bit on the left channel. Tried removing the resistors as some guides for different boards suggest but the same result. I tried lifting the pins for alternative points as suggested in the original MV-1X guide and soldering to that, still the same result. Build another MV-1X board, with the exact same result.

So my question is, is it even possible to stereo mod a MV-1ACHX or am I missing something?
 

Relo

n00b
Joined
Mar 14, 2015
Posts
19
I use the MKL mod, seeing as that's what the MV1X is based on, it's just the SMD variant. https://circuit-board.de/forum/index.php/Thread/25570-Neo-Geo-MVS-Stereo-RGB-Mod/?pageNo=1
Also have build an non-smd version with the same results though.

And I did use that guide, but the ACHX board has a different layout, but based on the guide you send and the MV1X guide the correct points should be the same as on the 1A board on Jamma Nations. (Based on pictures I don't even see the difference between 1AX and 1ACHX boards)
 

DaisyAge

Galford's Armourer
Joined
Jun 10, 2018
Posts
457
If you used the correct point then I'm guessing something is wrong with your stereo mod. Did you buy a pcb or make the circuit yourself? Attach some pictures if you could. I had the same problem my first time making the mod and I found that I had not connected one of the transistors to the output correctly.
 

Relo

n00b
Joined
Mar 14, 2015
Posts
19
bought the PCB, placed the components myself.
https://imgur.com/a/sdrMKaY

Edit:
Tested the connection points by simply removing a resistor that would normally decouple the audio (without any mod installed). It does kinda decouple the audio in that it makes one side lower in volume (I guess something like 70% of the full volume of the non disconnected channel), works for both channels. So at least I can rule out the mod itself as it seems the left and right channels come out of the c844g partially mixed already.

edit2:
Signals seem to already go into the op-amp partially mixed...

Edit3:
Got another MVS, this one is a 1FZS which does stereo fine.
 
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