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60, 65 SX, and 80 - Power Supply

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

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

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

Primary Power Supply Voltages

* 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 Supply Variants

Three variants were spotted:

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

The power supplies have the same form factor and pinout for all 8560, 8565, and 8580 models. However, there is some variation in their power capacities. Earlier models of the 8580 are rated at 225 watts, and later models were 242 watts. The 8560 models are either 207 watts or 225 watts.

225 Watts PSU 72X6665

Schematic: PDF | GitHub (by Eric Schlaepfer aka "Tube Time")

IBM P/N 72X6665
IBM REV A58491
PEC 3978
Assembled in Mexico

Output

100 - 125 V AC, 50/60 Hz, 4.5 A
200 - 240 V AC, 50/60 Hz, 2.5 A

Output

225 Watts
12 V DC / 7 A
5 V DC / 27.25 A
-12 V DC / 0.39 A

Power Switch Failure Rate

Peter says:
   Half of the Model 80 PSUs failed with a broken power switch. 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.

Device Power Consumption (by Fred Spencer)

When using the smaller wattage power supplies, it is advisable to use caution when the number of drives and adapters approaches the maximum. I understand that tables were available which allowed calculation of the total actual power requirement. If someone can locate this information on the web, I will provide a pointer here. Otherwise, the information is sometimes available within the IBM announcement letter, sometimes within the appropriate IBM Technical Reference document, and various OEM sources for non-IBM parts. I expect that any problems will probably result with the use of "older" adapters and full height disk drives. For example, the maximum power requirements for the 8514/A Display Adapter are 16 watts on the +5 volt supply and 0.22 watts on the -12 volt supply!

In order to assist with power calculations, you will find some valuable information at this IBM Support Site.

Information available in the IBM Personal System/2 Reference Guide suggests that IBM 16-bit adapters will probably require 7 to 10 watts each and IBM 32-bit adapters will probably require 7 to 13 watts each. The information available on original fixed disks is dated, but suggests:

For the really serious technical types, Louis Ohland has provided the following diagram of the minimum and maximum voltages available from the connectors of these power supplies. The nominal values are either 5V and 12V, of course.