MSX fenner spc-800 power supply

By mjnman

Supporter (16)

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13-06-2022, 12:13

I found a MSX fenner spc-800 but without the PSU components.
The need power for logical board seems to be, +5V GND +12V -12V and R.C.
What is the R.C. connection?
Can I build the PSU missed part?...maybe with a scheme printed by PCBWAY?
Below a picture about actual status.
Thanks

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By lintweaker

Champion (437)

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13-06-2022, 12:53

Some off the shelf Meanwell could provide the required +/- 12 and 5V. Not sure what the RC is for (reset circuit?).

By gdx

Enlighted (5686)

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14-06-2022, 02:39

You can use a 5V power supply (at least 3.3A) and do like this japanese guy for -/+12V.
https://nuneno.cocolog-nifty.com/blog/2019/04/post-1fdb00.html

By Wierzbowsky

Guardian (3489)

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14-06-2022, 04:01

Those Chinese PSUs get pretty hot. Don't repeat my mistake:
https://www.msx.org/forum/msx-talk/hardware/installing-an-in...

By mjnman

Supporter (16)

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14-06-2022, 14:59

I found MEANWELL RT-65B. From datasheet "High Operating temperature up to 70°C".
There may be temperature issue?

Below the picture of a original PSU with R.C. cable point.

By gdx

Enlighted (5686)

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14-06-2022, 15:11

Your MSX consumes much less than the MEANWELL RT-65B can provide, so it will heat up much less, but if possible try to put the heatsink towards a more airy side.

By Wierzbowsky

Guardian (3489)

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14-06-2022, 16:22

The heat in those PSUs is distributed from the heatsink to the entire metal enclosure. If you remove the enclosure in order to fit the PSU in, then it starts overheating. The control temperature measurements were taken from a fully assembled PSU that was working in a ventilated environment, not inside a tight plastic box.

By gdx

Enlighted (5686)

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15-06-2022, 17:15

I was just thinking of rotating the PCB so that the heatsink is not placed very close to the transformer as it is in the photo.

By mjnman

Supporter (16)

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10-08-2022, 11:51

I bought the MEANWELL RT-50B. It's a smollest from version MEANWELL RT-65B.
I secured with hot glue and MSX worked.
Thanks guys. Hannibal

By Wierzbowsky

Guardian (3489)

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10-08-2022, 13:26

Nice! But T30B would have been quite sufficient.