3550 Expansion Unit

@E9FE.ADF IBM Expansion Unit Model 001
@E9FF.ADF IBM Expansion Unit Model 002
@8EF8.ADF Expansion Unit SCSI Controller
C8EF8.ADF Init file for Expansion Unit SCSI Controller

3550210a.exe Option Disk (v1.0): Docking Station 3550

192-258  IBM 3550 Expansion Unit Model 001
192-257  IBM 3550 Expansion Unit Model 002

Power Supply

The -001 version is for the 8551 (N51) and the -002 version is for the 9552 (TP700/720).

3550 Planar
3550 Riser
   J3 Pinout
Install Adapters
Open Card Retainer Catch
HD Trays

3550 Planar FRU P/N 49G2667 (-002 model)

J1 Video pass-through
J2 P1 Power connector
J3 P2 Power connector
J4 External SCSI Connector
J5,6 Internal SCSI Connector
J8 120-Pin Connector
J9 Serial Connector
J10 System Board-Sub Connector
J11 Parallel Connector
J12 Pointing Device Connector
J13 Keyboard Connector
JP1 Password clear?
OSC1 40.0000 MHz osc
OSC2 24.0000 MHz osc
RA1-6 Termpacks
U2,25 Hitachi HM6264ALFP-10T
U3 49G2704
U5 AN78N05 VR
U7 Signetics P80C32GBAA MCU
U9,11 89F7000
U12 39G8766
U16 48G8903

Odd configuration. The system board component side faces DOWN. The circuitboard on top is covered with a insulating shield.

Note: The built-in SCSI controller (-002 only?) includes an active terminator. This terminator automatically works when an external SCSI device is attached.

3550 Riser

PL1 System Board-Main Interface
J3 LED and Power connectors
BT1 Backup Battery CR-2032
J1 16-bit AVE slot
J2 16-bit slot

The edgecard goes upward into J10 on the System board. J3 points to the front of the case.

J3 Pinout
 1 Brown    +Modem
 2 Red      +FDD
 3 Orange   -FDD
 4 Yellow   -PCMCIA
 5 Green    +Charge
 6 Blue     -Speaker
 7 Purple   -Modem
 8 Grey     +HD
 9 White    -HD, -Charge
10 Black    To keylock switch
11 Red      To keylock switch
12 Red      To Power Switch
13 Black    To Power Switch
14  N/C
15  N/C

Not totally sure- the LED PCB has some bussed pins.

Installing Adapters
  You can install two full length 16 or 32 bit cards in the 3550 (but only permit 16-bit operation). Another gotcha- The slot cover guides are the same as on other microchannel systems. But the catch for the card guide is a sliding catch, not a flexible one like on the 76/77 models.

To open the catch
  Look at the vertical card guide restraint. About 2/3rds down, there is a horizontal tab. Push in on the end of the tab, then push the card guide restraint forward until it reaches the stop. To fasten it back, just slide it to the rear until the locking tab snaps into place.

Drive Tray for HDs
  When installing a 3.5" drive in a 3550 Expansion Unit, use the hard disk drive slide assembly (FRU 85F0035) supplied with the option. (Ed. a model 95 sled). The 3550 uses snap-in rail guides like those in the 77 series.

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

Ardent Tool of Capitalism is maintained by Tomáš Slavotínek.
Last update: 08 May 2024 - Changelog | About | Legal & Contact