Sakhr AX170 (Sanyo MPC-2) audio modification

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Por wbahnassi

Expert (112)

Imagen del wbahnassi

11-09-2019, 14:14

Grauw wrote:

Yes indeed!

Dammit! I'll do the mod asap. Thanks! Big smile

Por wbahnassi

Expert (112)

Imagen del wbahnassi

15-10-2019, 04:51

I finally managed to get some time to do the mod. Thanks a lot Omega, it works perfectly!
I've recorded a short video showing the difference while I was in the process. I started with 1.5k resistance, but found that in general it left SCC a bit overtaken by PSG still. After a bit of trial I think 1k ohm hit the spot, so I soldered that in.
Interestingly, I noticed your AX170 has additional circuitry near J213 that mine doesn't have. I guess that's the RGB output stuff? Mine doesn't have this.

Anyways, thanks a lot for the great find. Now my MSX sounds right with SCC games :)

Por Omega

Master (223)

Imagen del Omega

16-10-2019, 17:52

Good stuff!
I'm happy that I have at least helped one other AX170 Smile
Not sure about the RGB circuitry but quite possible.

Por wbahnassi

Expert (112)

Imagen del wbahnassi

24-11-2019, 13:25

For the record, I found this page in King's Valley 2 manual mentioning this issue, along with a list of bugged MSX models:

Por michellybells

Rookie (18)

Imagen del michellybells

27-07-2020, 02:07

I wanted to do this same fix, because I have a Wavy 2 (MPC-2) which is the original Japanese version of the AX170. However, after opening the system up, I noticed that the design of the board is slightly different from the AX170. None of the numbers for the jumpers and resistors are the same, so I don’t know where to solder to. I found the jumper point where the audio from the cartridge slot is carried to the sound output, but unlike the schematic for the AX170, there doesn’t seem to be a 100uf cap or a 100ohm resistor in the path between the cartridge slot and the audio output connection point. This means that SCC (and any audio from cartridge pin 49) seems to be going direct as is to the audio output. Any hope of a new schematic to help me do this audio mod?

Por Omega

Master (223)

Imagen del Omega

10-08-2020, 15:18

I can't reverse engineer an MPC-2 board because I don't have one. Feel free to send me yours though LOL!
Or do it yourself.. follow all the traces, draw something on paper, find all the components and values.

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