Philips Music Module mods

Scribe (6573)

21-05-2018, 20:58

I've got several Philips Music Modules. Of two of them I know what they're about. On the picture they're to the left. The ones to the right came later and had some mods on them before I got to know them.
From left to right they'll be 1, 2, 3 and 4 for now.
1. is default
2. is expanded to 256kB sampleram and works properly on clockspeeds other than 3.5MHz
3. works properly on clockspeeds other than 3.5MHz
4. is expanded to 256kB sampleram

The first two are certain. There's nothing less and nothing more to them. It's number 3 and 4 I am a bit uncertain of. What's mentioned above is what I know. But is there more?
Number 2 and 3 work on higher clockspeeds. In number 2 there's some piggybacking to the left between the midi ports and the memory expansion while on number 3 there's a small pcb with a crystal on a piggyback on another place. This confuses me.

If anyone can tell me what has happened to number 3 and number 4 I'd be quite happy. And if 3 only has a clockspeed fix, then why isn't it done like number 2?

The picture:
http://meits.nl/files/msx/musicmodules.jpg (for full size)

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Par Zilogger

Resident (39)

29-05-2018, 18:24

Meits,

Funny, that u like configuration 2.
An EXO-3 oscillator 14.31818 MHz with a 3 bits divider.
256kb Sample RAM with 2 x 414256 Dynamic RAM and a SMD 74LS125.

Par meits

Scribe (6573)

29-05-2018, 21:00

Thanks for a reply.
For me it's quite interesting to know what the clock speed fix is, since I was willing to transplant the one from nr. 3 to nr. 4 in order to have two more or less the same modules. But as I opened nr. 2 and nr. 3 I was confused what the clock speed fix is. Since it's not 1:1 there's not a lot I can do with only some basic solder skill/courage. I wouldn't know what I'd do if I did it.