MSX PSU help

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Van S0urceror

Master (194)

afbeelding van S0urceror

05-09-2021, 20:43

Grauw, you are right. Both inside and outside are very well manufactured. The PCB is a work of art although it's hidden inside. Everything in clearly labeled sections and indeed two sided and on one side two layers.

What are you going to do with the PSU? Keep it original and use an external step-down converter to 110 volt AC?

I did a bit more research and it looks like I'm going for an external 12V power brick and a PicoPSU that generates all the voltages. And use the old power cable hole to receive a barrel jack.

Van Grauw

Ascended (10164)

afbeelding van Grauw

05-09-2021, 21:07

And the one side is almost entirely ground plane! I wonder if that is to reduce interference noise. Maybe it improves audio quality, I’ll pay attention to that (although I doubt it can beat Yamaha).

Yeah I’m keeping the PSU original and connect it via my UT-130E step-down. Are you looking for a replacement because it is not functioning or because you want it to connect directly to 230V?

Van Meits

Scribe (6462)

afbeelding van Meits

05-09-2021, 23:17

S0urceror wrote:

What are you going to do with the PSU? Keep it original and use an external step-down converter to 110 volt AC?

I would not recomend using a 110V AC adapter. They can easily output more than 110V and that's outside the 10% margin of the 100V PSU. The ones left lying here do 114V.

Van Grauw

Ascended (10164)

afbeelding van Grauw

06-09-2021, 00:58

Meits wrote:
S0urceror wrote:

What are you going to do with the PSU? Keep it original and use an external step-down converter to 110 volt AC?

I would not recomend using a 110V AC adapter. They can easily output more than 110V and that's outside the 10% margin of the 100V PSU. The ones left lying here do 114V.

See wiki page Power Transformers. The UT-130E is the one I’ve got.

By the way, I poked around with the oscilloscope on the MB46H444 gate array pins, because I was wondering whether it had an RA8 output like the MB670836 used in the HB-F1XV and HB-F1XDJ does, which would allow memory expansion to 256K. But alas, I did not get any signal on the unconnected pins 1, 2, 19, 33, 34 and 51 and 64 with the mapper registers set to FF, FE, FD, FC.

I also tried the disk drive just now, it is working fine. A direct drive type too, no belt, that’s nice.

The audio level is very low though, I think that’s a symptom of the HIC-1 cap C14 being dead.

Van sdsnatcher73

Prophet (2349)

afbeelding van sdsnatcher73

06-09-2021, 07:54

Low audio level is indeed caused by the caps on the HIC-1 board.

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