Common MSX Voltages questions

Door Underscore

Rookie (22)

afbeelding van Underscore

07-03-2020, 09:47

Hi.

Many MSX use voltages like 5v, 12v, their negative counterparts.
My questions are:

Is it possible to power an MSX just with +5volts, 2A?
What is the 12volt line used for? Apparently, the cartridge slot has a +/-12v line there. Is it necessary for running most games and software?

How much current a normal MSX will draw in general during gaming? Can we work only with 1A or 2A might be needed in many cases?

Thanks.

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Van Jipe

Paragon (1586)

afbeelding van Jipe

07-03-2020, 10:00

yes you can with just a 5V power, i testing on a VG8235 for this mod
http://msxvillage.fr/forum/topic.php?id=1703&pt=5
820ma with a cartridge insert in a slot
but many MSX1 use -5V for the memory

Van gdx

Enlighted (5996)

afbeelding van gdx

07-03-2020, 10:12

+/-12V is used mainly by sound expansions (FM-Pac, etc).
Only few MSX1s that have old RAMs use the -5V internally.

Van Wlcracks

Champion (492)

afbeelding van Wlcracks

07-03-2020, 10:55

Audio opamps could use it.
Maybe video amplifiers.
I did it with my vg8020/00 when repairing. It was at 5V 0.9A without any expansions, just plain motherboard.
I would recommend checking the schematic first.
Z80 is always running at full speed, i dont think current will change at performance change.

Van Underscore

Rookie (22)

afbeelding van Underscore

08-03-2020, 15:17

Ok, thanks for the info. Very useful ????