3511 External SCSI Enclosure

190-178 IBM Personal System/2 External Storage Enclosure for SCSI Devices (3511-003)
ZG90-0228 IBM PS/2 External Storage Enclosure for SCSI Devices (3511-004)

S15F2158 IBM PS/2 Ext Storage Enclosure For SCSI Devices HMR (BOO format)

IBM 3511 PS/2 SCSI Expansion Box (video by uniservo)

Common Devices
Power Supply
Operator/Indicator Panel

Load Distribution Card
   Load Distribution Card Schematic
3511 Chassis


  • 7 half-height (non-array) or 7 slim hot-swap + 2 half-height bays (array)
    • Up to 7 hard disks
    • Up to 2 CD-ROM drives
    • Full-height SCSI Tape Drive for backups
    • 3.5" Rewritable Optical Drive
  • SCSI interface
  • 329 W (non-array) or 399.1 W (array) power supply

Load Distribution Card FRU P/N 64F0139, P/N 57F2092 [P] [P] [P] [P]

J1 Power Supply Connector
J2 Molex power connector
J3 Op Panel Connector (10-pin)
R2,3 Pads for dummy load resistor (5 V)
R4-12 Dummy load resistor (5 V)
ZM1 74LS14 Hex Schmitt Trigger Inverter

Load Distribution Card Schematic

3511 Chassis (photos by an unknown ebay seller)

The 3511 is based on the 8595 1S1P chassis.

The I/O opening and 5 of the 8 MCA slots are blocked from the outside by a plastic cover. Slot #1 holds an external SCSI connector.

The planar is replaced by a small Load Distribution Card that connects to the PSU planar connector, provides a dummy load for the +5 V rail, and a connection to the Op Panel.

More photos can be found HERE (courtesy of "Mad Max" and an unknown ebay seller).

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