Something strange I found out about regarding the SCC chip

Door Omargrafx

Resident (43)

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12-11-2018, 16:32

I was playing some Nemesis 2 and on my Sakhr AX170 (Sanyo MPC-2) model and noticed some sound is missing. Then, I loaded it into my Sakhr AX370 MSX2 (Sanyo Wavy70FD) and noticed that the sound works and is there. Maybe it's because I loaded it into the second cart slot on my AX170, and on the first on my AX370, because I own King's Valley 2 and as far as I know, it works fine on my AX170. Anyone else experienced the SCC chip not working in certain models?

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Van mars2000you

Enlighted (6229)

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12-11-2018, 17:14

A problem for the PSG/SCC balance is known for all Philips computers manufactured by Sanyo: NMS 8250 - 8255 - 8280 that are based on Sanyo MPC-25 and MPC-27. I guess there are similar problems on other machines manufactured by Sanyo.

See this doc: http://www.msxarchive.nl/pub/msx/mirrors/hanso/hwdoityoursel...

and this page: http://frs.badcoffee.info/hardware/MSXfixes.html

Van meits

Scribe (6502)

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12-11-2018, 17:17

There's a flaw in the cartridge ports of those machines causing PSG and SCC to collide in the mix. For the Philips 8250 and up the fix is not too hard. I've never seen any of the others from the inside.

Van gdx

Enlighted (5512)

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13-11-2018, 09:06

SCC cartridge are all designed in the same way. Contacts are probably bad or a capacitor is defective somewhere. The sound filter of AX170 may be sensitive to a problem like that kind.

Van Omargrafx

Resident (43)

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04-04-2019, 22:54

Sorry if I'm necro-ing, but I tested out Nemesis 2 on my AX123/AX230, and it has the same problem.