POWER-SUPPLY TESTS

POWER-SUPPLY TESTS Mod. 33, 35/40, 56/57, 76/77, 85, 90 and 95

The Problem: You have a Mod. 33, 56/57, 76/77, 90 or 85 / 95 and want to test the power-supply. Bad luck: these power-supplies are switched electronically over the systemboard and have no AC-switch. What if the board is dead or the tiny little switch in the front-panel is broken ? Isn't there a way to test the power-supply without the system around ?The Solution: Yes - it is possible to test these units. Look in this page.

Mod. 95 Power Connector 3 6 9 12 15 18 21 ----------------------+ Notch-- / o o o o o o o | +---2 | o o o o o o o | 20 | | o o o o o o o | | +-----------------------+ +--------1 4 7 10 13 16 19 GND +Pin Voltage DC(min) DC(max) ------+-------+--------+--------+-------- 5 | 3 | +5V | +3.7 | +6.2 5 | 4 | +12V | +9.0 | +15.0 5 | 7 | -12V | -9.0 | -15.0 ------+-------+--------+--------+-------- [Fig. 1: Connector on PS/2 Mod. 85, 95 and 3511 power-supply] If you have opened the cover and removed the power-supply, connect the power-cord back to the unit. Then short-circuit the pins 1 and 2 on the power supply.The power-supply cooling fan must come up almost immediately - if you hear just a tiny clicking noise from the unit and have the short checked again for a good connection the power-supply is defective and has to be replaced. If the built-in fan comes up, check the 3 testing points for their appropriate voltages. If they are within the given range the power-supply appears to be functional.

Mod. 90 Power Connector 9 8 7 6 5 4 3 2 1 +-----------------------------+ | ## ## ## ## ## ## ## ## ## | ++ +-+ +--------------------------+ be be rd rd rd rd rd rd bl P1 +--+ V V 9 8 7 6 5 4 3 2 1 +-----------------------------+ | ## ## ## ## ## ## ## ## ## | ++ +-+ +--------------------------+ yw wt bl bl bl bl bl bl or P2 be = Blue, rd = Red, yw = Yellow, wt = White, bl = Black, or = Orange GND +Pin Voltage DC(min) DC(max) ------+-------+--------+--------+-------- P1 1 | 2 | +5V | +4.8 | +5.25 1 | 8 | +12V | +11.5 | +12.6 ------+-------+--------+--------+-------- P2 2 | 1 | -12V | -11.5 | -12.6 ------+-------+--------+--------+-------- [Fig. 2: Connectors on PS/2 Mod. 90 power-supply] If you have opened the cover and removed the power-supply cables P1 and P2, connect the power-cord back to the unit. Then short-circuit the pins 7 and 8 on the power-supply connector P2.The power-supply cooling fan must come up almost immediately - if you hear just a tiny clicking noise from the unit and have the short checked again for a good connection the power-supply is defective and has to be replaced. If the built-in fan comes up, check the 4 testing points on P1 and P2 for their appropriate voltages. If they are within the given range the power-supply appears to be functional.

Mod. 33, 35/40, 56/57, 76/77 Power Connector +-----------------------+ |+---+ +---+ +---+ +---+| || # | | # | | # | | # || || # | | # | | # | | # || || # | | # +-+ # | | # || |+---+ +---------+ +---+| +-----------------------+ 1 2 3 4 P1 +---+ V V 7 6 5 4 3 2 1 +---------------+ | | | # # # # # # # | +++-----------+++ ++ ++ P2 GND +Pin Voltage DC(min) DC(max) ------+-------+--------+--------+-------- P1 4 | 1 | +5V | +3.75 | +6.25 ------+-------+--------+--------+-------- P2 6 | 7 | -5V | -4.75 | -5.5 6 | 1 | +12V | +9.0 | +15.0 6 | 5 | -12V | -9.0 | -15.0 ------+-------+--------+--------+-------- [Fig. 3: Connectors on PS/2 Mod. 33,56/57,76/77 power-supply] If you have opened the cover and removed the power-supply cables P1 and P2, connect the power-cord back to the unit. Then short-circuit the pins 6 and 4 on the power-supply connector P2.The power-supply cooling fan must come up almost immediately - if you hear just a tiny clicking noise from the unit and have the short checked again for a good connection the power-supply is defective and has to be replaced. If the built-in fan comes up, check the 4 testing points on P1 and P2 for their appropriate voltages. If they are within the given range the power-supply appears to be functional.