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.
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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]
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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.
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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]
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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.
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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]
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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.
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I'm ready for feedback & comments !
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