Fujitsu FM Towns II PSU Repair

Fujitsu FM Towns II Repair

I start to saying how much i hate repairing psu switching, one of the most boring things second only to the repair of CRT Monitor, at least for me.

However this repair was made. The failure is almost certainly caused by a copious spillage of electrolyte (conductive fluid usually formed from a salt solution or acid which is located inside of the electrolytic capacitors) and a dangerous test if the machine works again after the electrolyte was leaking over the pcb.

The moral of the story is easy to figure out, a short circuit has made several deaths, a good portion of the Primary (PWM) and Secondary.

The components that have been replaced are the following:

  • 1 x Electrolytic Capacitor 3300µF 16v 105°
  • 1 x Electrolytic Capacitor 1000µF 25v 105°
  • 1 x Electrolytic Capacitor 2200µF 35v 105°
  • 1 x Electrolytic Capacitor 1000µF 100v 105°
  • 1 x Electrolytic Capacitor 330µF 160v 105°
  • 1 x Electrolytic Capacitor 47µF 25v 85°
  • 1 x Electrolytic Capacitor 10µF 100v 85°
  • 1 x Electrolytic Capacitor 22µF 25v 85°
  • 1 x Sanken Hybrid Voltage Reculator Module STR 53041
  • 1 x Photocoupler TLP 541G
  • 1 x Overcurrent Protection Elements ICP N10
  • 1 x Transistor C1815GR
  • 1 x Transistor DTC114 ESA (C114 ESA)

After 1 week i have decided to replace also all capacitors of the power supply section of the computer.

Components replaced:

  • 1 x Electrolytic Capacitor 3300µF 25v 105°
  • 3 x Electrolytic Capacitor 5600µF 10v 105°
  • 1 x Electrolytic Capacitor 2200µF 10v 105°
  • 1 x Electrolytic Capacitor 330µF 35v 105°
  • 1 x Electrolytic Capacitor 1000µF 16v 105°
  • 1 x Electrolytic Capacitor 470µF 25v 105°
  • 1 x Electrolytic Capacitor 1µF 50v 105°

Gallery of the repair:

  1. RetroRepair
    September 17th, 2014 at 23:45 | #1

    Great article! I just had the same issues with a Towns 2 and though I did as you did and replaced those parts, the monitor still won’t turn on and the cd drive isn’t reading any discs, though it does power on. I don’t think it’s booting :(

    Any idea what I should look at next?

  2. RetroRepair
    September 18th, 2014 at 17:05 | #2

    Well I tested with an external source (FM Towns 1) and still no image. I’m certain the monitor isn’t turning on. Not really sure what to do from here aside from replacing all the remaining components.

  3. RetroRepair
    October 2nd, 2014 at 14:41 | #3

    Ok well, I had to replace also the other two N10 OPEs as well as two C2236 transistors but it works!!

    I get the boot logo but it’s not reading the disc. I am so happy I go this far though!

  4. 1983parrothead
    December 6th, 2015 at 21:55 | #4

    Some people said that it is best to purchase a working PSU over fixing a damaged one. Unfortunately, finding a new one is next to impossible. But repairing is risky due to how lethal electricity is. I have a FM TOWNS II HR model and it doesn’t stay on. It turns itself off after a few seconds or couple of minutes.

    What should I do?

  5. Samson
    March 29th, 2016 at 05:19 | #5

    I have an older model Towns and I’m trying to figure out why the volume indicator LEDs aren’t lighting up. Is it possible that’s caused by a bad capacitor?

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