8560, 8565 SX and 8580 - Power Supply

Repair of PS/2 Model 8580 Power Supply (by Al Savage)

Power Supply Variants
Removing Power Supply
Planar Power Supply Connector Pinout
Primary Power Supply Voltages
Power Switch Failure Rate
Power Supply Crackling Noise


Power Supply Variants

Three variants were spotted:

  • 225 W, FRU 15F6548, 12 V / 7 A, 5 V / 27.75 A, -12 V / 0.39 A, red switch
  • 242 W
  • 250 W, FRU 57F1600


Removing Power Supply

Power off and unplug the system!

Remove rear drive carrier from DASD support structure. Unplug any four pin drive power cables. Unplug the planar power plug. Remove the three screws that hold the PSU in. Pull PSU out.


Planar Power Supply Connector Pinout

  Pin(s) Description Notes
  1,4,7,10,13 +5 V DC Top row - all, bottom row - pin 10.
  2,5,6,8,11,14 GND Middle row - all, bottom row - pins 13, 9.
  3 +12 V DC
  9 -12 V DC
  12 Power Good +5 V if all voltages are stabilized
  15 Hard-Drive LED Active when high


Primary Power Supply Voltages

-Lead Pin +Lead Pin Rail Vdc Min. Vdc Max.
29-12 V DC-9.0 -15.0
23+12 V DC+9.0+15.0
21+5 V DC+3.7+ 6.2
BD+5 V DC+3.7 *+ 6.2 *
CA+12 V DC+9.0 *+15.0 *

* Disconnect the 15-pin connector from the system board before taking this reading.

If the voltages are not correct, or if the fan is not running, replace the power supply.


Power Switch Failure Rate

Peter says:
   Half of the Model 80 PSUs failed with a broken power switches. The red ones more often than the white ones. The same switch has been used in IBM 327x Terminals (and 525x ones) and is known for high failure rates. It was available as spare part.


Power Supply Crackling Noise

Edward Avis says:
   One thing worries me about my 8580's power supply - it crackles. When the machine is switched _off_ there is a quiet crackling sound from the back of the power supply, it sounds like it could be in tune with the 50Hz mains frequency. When I first heard it I nearly took the machine back for a refund, but it doesn't seem to have any effect.

Peter:
   Are you sure the noise comes from the rear ? The "switch cover" in the front acts like a "echo chamber" and reflects the crackling from the switch to the rear. On the other hand: it might be an isolation failure on the AC Line filter as well. Or on one of the capacitors of that filter. Had that too. You will have to open the PSU for a failure diagnosis ... and you should *know* what you are doing in this case. It is dangerous to fiddle with the innards of switched power supplies.

   Something I forgot: One of my 95s made "crackling noises" too. The clue: replace the power cord. The one I used seemed to have too loose contacts. After I used a different one the crackling went away.


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