8550/70 756x Power
Power Supply Pinout
7561 / 62 PSU Specs
8570 PSU Specs
8550 / 50z PSU Specs
Add Power Connector
Power Supply Pinout
Same for 8550 (94w), 8570 (132w) and 756x (180W).
P/N 33F5202 FRU 57F2728
Made by Plessey in Italy....
Input 95-120v @ 3.6A 50-60Hz, 200-240v @ 1.9A 50-60Hz
Battery Charger 26v dc @ 40mA
This PSU has an external, two pin Molex connector that provides
power to the case fan. There is a 9.25"Wx1.75"H inch hinged cover on the
lower outer side of the psu. It is fastened at the front by a single captive
standard screw. The cover pivots open on the rear hinges, revealing a three
pin Molex power connector, like a female drive power connector. The battery
cavity is 1.875" deep.
Made by ASTEC, Model AA15530, IBM PN 90X9409, FRU 90X8626.
Max continuous output power is 132 watts for the 8570 PSU.
8570 Voltage per Pin
Voltage (DC V)
Pin # Current/Pin
15-47 Odd #s only 1130
2-48 Even #s only 915
Rich keeps me honest
The original one coming with Mod 50.50z was rated 94 watts,
no fan. HMM says part number is [90x9366]. (Ed.
He's right, I remember the fan assembly that slides in at the back of the
case. Old age, I guess...)
MODEL NO.: AA13621 IBM P/N: 90X9527 IBM
FRU P/N: 90x9366
PIN NO. CURRENT/PIN
15-47 ODD NO. ONLY 760
DC RTN 2-48
EVEN NO. ONLY 640
SYSTEM STATUS 49
Max continuous output power is 94 W.
This is from a 50Z. No side blower. (The blower
plugs into the motherboard, is supported by two plastic snaps to top rack,
and it blows out the rear of the 50/50z unit). CASE BOTTOM of power supply
does not have a screen, it has finely punched holes, 11 or 10 holes across,
the length of power supply.
Cases vary color, gold/silver. Security
torx, 5 on side 2 on top. Like unto Mod 70 supplys, except no side blower,
and lower rating.
Remove the Power
Supply (8550 / 50z / 70 similar)
Remove the two screws at the back of the case. Remove
the screw at the front inner corner. Pull PS out from planar.
Power Supply Cleaning
8550 / 50z
The way the 50 / 50z PSUs were built, they have a screen
across the bottom side. Just like on a clothes dryer, you have to remove
"lint" from the screen. I used a T-10 security Torx to open it.The fan
is a Panaflow DC Brushless, Model FBH-09A12L, 12v 0.14A or a Nidec Beta
SL Model D09B-12PLL 12v .09A
These have the built-in fan. Use a T-10 to open.
8570 / 8550 Bus Riser
Power Hack FRU 90X1111
Please note that clone PC power cables use yellow/black/red,
while IBM systems use yellow/black, or red/black/blue. What is important
is the position of the conductor. Note that the drive power connector is
keyed with bevelled edges.
JN1 Floppy 1 (A:)
JN2 Floppy 2 (B:)
The three resistor/capacitor pairs on the riser are for
DC-buffering and decoupling. The earlier risers lacked them and once you'd
stuffed in 2 FDDs or 1 FDD and a tape problems occured with loss of data
during copying and suchlike.
From Peter Wendt
9595 Main Page
Warnings and recommendations:
The maximum power from this hack is about 5v/1A
and 12v/1A so if you have both disk-drives or one disk-drive and a tape-streamer
installed ... it is probably not a good idea anyway. It will -non
the less- work in most cases, until the unit driven over this port doesn't
take too much power. Most modern Harddisks will not exceed these limits.
In case of doubt: consult drive manual for its power-consumption. Or don't
do the modification.
If you have only one disk-drive installed, take
the connector of the second drive for modification. Caution!! Take
care not to damage the tiny connections on the board near the connector
for Drive 2 while soldering the wires.
Remember, that the Mod. 50 / Mod. 70 power-supplies aren't that
powerful at all. Especially the Mod. 50 power-supply (94W!!!) is known
to have lesser power than assumed. If you'd already installed a -386/-486
upgrade, 64Megs of RAM, SCSI-adapter and a Hi-Resolution graphic board
it will surely collapse.