Author Topic: FM Towns PSU  (Read 2608 times)

Offline caius

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Re: FM Towns PSU
« Reply #40 on: December 11, 2016, 08:32:14 am »
I successfully replaced the PSU in my FM-TOWNS II MX with a standard ATX :

https://www.youtube.com/watch?v=87RLYVn58A4&feature=youtu.be

The adaption was easy, I quickly figured out the pinout of the connector on motherboard (16PIN molex but it can differs in other FM-TOWNS models).
The voltages needed (+5V, +12V, -12V) for powering the FM-TOWNS are present on a ATX PSU along with the +5VSB but colors of wires of the FM-TOWNS PSU mean different voltages compared to ATX.This is the adaption diagram valid for all FM-TOWNS models (but check always with a multimeter)

BLACK=GND ---------------------->same of ATX
BROWN=+5V---------------------->RED ON ATX
RED=+12V------------------------->YELLOW on ATX
ORANGE=-12V--------------------->BLUE on ATX
YELLOW=+5VSB------------------->PURPLE on ATX

On the FM-TOWNS PSU there is also a white wire, this seems to be connected (but not used) to the rear fan connector, we can omit it in this adaption.
As said, the original power switch cannot be used since the FM-TOWNS power up works in a different way, specifically the original switch is a momentary one which briefly shorts the PS-ON signal (BLUE wire on the FM-TOWNS PSU) to GND.So you have to install a simple ON/OFF switch that keeps shorted to GND the PS-ON signal of the ATX PSU (GREEN wire) for the time the PSU must be ON.Here's a picture :




I hope this can help you all to replace your faulty FM-TOWNS PSU.If you have any question, don't hesitate to ask.
« Last Edit: December 20, 2016, 08:29:51 pm by caius »

Offline kamiboy

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Re: FM Towns PSU
« Reply #41 on: December 12, 2016, 01:05:11 am »
Great work documenting this stuff. With how rickety Towns PSU's are I am sure this will of great use to many.

Offline Tw3ek

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Re: FM Towns PSU
« Reply #42 on: December 16, 2016, 02:15:23 am »
Tested this today with a previously broken FM Towns unit and it once again powers on. Thanks so much caius for the work and the help!

Offline caius

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Re: FM Towns PSU
« Reply #43 on: December 16, 2016, 02:18:00 am »
Thanks to you for your feedback.In the next days I will post a more detailed tutorial on www.jammarcade.net

Offline famiac

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Re: FM Towns PSU
« Reply #44 on: January 28, 2017, 01:59:03 am »
Cracked a couple of power supplies open and found that the notorious IC51 appears to be labeled on one of them.

Here's a photo:


Here's the datasheet

Offline caius

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Re: FM Towns PSU
« Reply #45 on: January 30, 2017, 08:55:23 am »
Very good find.