7552 Power

7552 Power Supply Supply
   AC Power Cord Hook-Up
   Front of Power Supply
   Remove PSU
   Dead PSU, or Is It Dead?
   Status Light Meanings
Power Supply Voltages and Current
Nicad Battery
   EVM Module
PSU Fan
Cleaning the PSU


Gearbox Power
   The 7552 is a direct-wire system, using a customer-provided power cable to an applicable power source. 260 total watt worldwide, autoranging (will detect and switch for 120 or 220) power supply, with two fans to assure system cooling.

AC Power Cord Hook-Up

 

 7552s wired for AC power have a terminal block mounted on the left side (or upper left rear corner). The black wire (shield) on the system side of the terminal DOES NOT attach to the terminal block.
 
 

C - Terminal Cover screws
S - Terminal Block screws

Power Supply (with EVM installed)

PSU made by Power Systems, Inc, model PS1617 IBM P/N 60X8906 (Same as the 7568)

PSU Connector Pinout

Remove PSU
   Turn power switch off on PSU. Unscrew the three screws on the bottom front edge. Grab on the cutout around the EVM/Battery pack on the left and grab the right corner of the PSU (though you might try the rightmost captive screw). Rock the PSU a little as you pull it out. The plug is at the back of the PSU behind the power switch. It resembles a mutant 95 planar plug. Do NOT grab the black plastic guard around the power switch!!!
Note: The three screws might NOT be captive ones like on the 7568! They must be totally removed to pull the PSU out. I have a second power supply, and it used captive screws.

Dead PSU or Is It Really Dead?
   I had two 7568s, one powered up, the other didn't. Swapped the PSUs, one worked in both cases, the other didn't work at all. These babies are built even heavier than a 95A PSU, so I was puzzled.

Dr. Jim did the office call and says:
   The tabs holding the thumbscrews at the bottom front of the PS were tweaked backwards.  Straightened them out so the PS seated fully. 

Status Lights Meaning

AC DC TEMP BATT FAN 1 FAN2 Possible Problem
O
X
O
O
O
O
1. AC power missing
2. Defective power supply
X
O
O
O
O
O
Defective Power Supply
X
X
X
O
O
O
1. Hi temp (poor ventilation?)
2. Defective power supply
X
X
O
X
O
O
1. Battery discharged or disconnected
2. Defective power supply
X
X
O
O
X
O
1. Fan 1 Malfunction
2. Defective power supply
X
X
O
O
O
X
1. Fan 2 malfunction
2. Defective power supply
X
X
O
O
O
O
AC OK - Power supply OK

Power Source Choices
   When the system is turned on, the PSU senses the applied power source. If AC power is present, the system starts and runs with AC as primary power. If DC power is present, it is used as a backup power source (requires EVM for extended backup time).
   If no AC power is present, the system starts and runs off DC power, if DC power is available at the battery connector (requires EVM to be installed). There is no backup capability in this configuration. Don't try running system off battery pack!!!
   The system sets operating mode (AC or DC) when the system is turned on. It remains in that mode until the power switch is turned off.



AC Specs
120vac 4.0A / 220 vac 2.0A Single phase.Power usage 260W 47-63Hz

AC Power Cable
   Any cable used must be a minimum of 18AWG with ground.

Power Supply Values
Max output 260 W
+5V @ 22A   -5V @ 0.3A
+12V @ 4A   -12V @ 1A
+6V @ 5mA
Battery Charger +28V @80mA
Fan Supply 15W max

PSU Pinout

Pin
Function
Pin
Function
1
+6v @ 5mA
13,15-20,22,24
GND
2-4,7,8
+5v @ 22A
14
-PR PWR CK
5
-12v @ 1A
21
-P/S CK
6
+12v @ 4A
23
BKUP DISC
9
-5v @ 300mA
25
DC PWR GOOD
12
-TEMP CK

BATTERY, NICAD (INTERNAL) (#6221) (P/N 60X9042)

This internally mounted battery allows continuous operation through brief main power interruptions (nominal 1.5 seconds default). Also, if the interruption continues beyond this period, the battery maintains DC voltages to allow the system to perform an orderly shutdown.

Note: Shutdown is limited to max of 10 sec under hardware control. Software control shutdown depends on the electrical load and the battery capacity, and may be limited to 10 seconds. Longer shutdown periods require external battery backup, which requires an EVM.

The battery pack is 21 (twenty-one) Sony Cadnica KR-SCH 1.2v 1200mAh, Standard charge14-16 hrs at 120mA, recommended trickle charge 40mA.

Looks to be an exact match to the 7568 battery pack.  IBM replacement PN 85N2685

EXTERNAL VOLTAGE MODULES (#6231 AND #6528):
These EVM features allow the connection of an external DC voltage source either for additional battery backup to the main AC power, or as a main DC power source. No other external voltages are to be used as a main source or as a backup.
EVM #6231 24 volts DC. 
EVM #6528 48 or 60 volts DC. 

Note: Either one of these EVMs (with a connected external DC voltage source), or the internal nicad battery (#6221) must be ordered and installed to retain system set up information during periods when the system is shut down.

The EVM provides RFI filtering, reverse polarity protection, and over voltage protection.

Warning! A fully populated Gearbox requires up to 30A on the DC line. Use a minimum of 14AWG



PSU Fan
   ETRI Model 98DW 98DW1LP31 203, 12v (8-15v) at 5.2W (under .5A)

Filter Use
   The 7552 can use optional filters in the PSU compartment. Use of filters degrades the maximum temperature decreases by 9°F/5°C.

Changing Airflow Direction

   Remove the PSU. Flip it upside down. If you can see the ETRI sticker on the fan hub, the PSU is set to blow down through the shrouds. This direction is used for the filter configuration. Unfortunately, the heat generated by the PSU is now blown through the shrouds.
   If you see a silver hub, the PSU is set to suck air up through the shrouds and out through the grilles in the PSU compartment. This is good because the heat from the PSU is not blown through the populated shrouds.

   Remove the three standard screws in each fan housing. Pull them out and flip them over to whatever way you want. If you are unsure about the direction, there are two arrows embossed on the fan housing, showing fan rotation AND airflow direction.



Cleaning the PSU
   Hooray! I stumbled onto this working on the fans...

  At first look, it's grim. Rivets everywhere. Don't give up. Flip PSU upside-down. Unplug fan power connectors. Remove all fan screws. Pull up on grille and push the fan power connectors through using a flat bladed screwdriver. Now the grill comes off, and the majority of the PSU components are exposed.

  Copper heatsinks! Stud power diodes!

Content created and/or collected by:
Louis Ohland, Peter Wendt, William Walsh, David Beem, Tatsuo Sunagawa, Jim Shorney, Tim Clarke, Kevin Bowling, Tomáš Slavotínek, and many others.

Ardent Tool of Capitalism - MAD Edition! is maintained by Tomáš Slavotínek.
Last update: 19 Nov 2021 - Changes & Credits | Legal Info & Contact