35, 40, 56, 57, 76 & 77 - Common Parts

Common Power
Front Panel Connector
Ultimedia Module

Cases, Planars, and Riser Cards
Unit Does Not Turn On (9556/57 9576/77)
PCMCIA Adapter Mounting


Cases, Planars, and Riser Cards

You can upgrade any current PS/2 56/57 or 76/77 with the later "Lacuna" Planar. You'll gain all the advantages of the new 76/77 i and s systems. Current 76/77 systems will perform up to 38% faster while keeping everything else intact.

Note: Models 35 and 40 are ISA-based, and can't be upgraded with a MCA planar (the chassis is slightly different).

There are two case sizes designed to accept the same planars:

3x3 case:
   8556 → 9556 → 9576 → 9576i (IDE) & 9576s (IDE + SCSI)
5x5 case:
   8557 → 9557 → 9577 → 9577i (IDE) & 9577s (IDE + SCSI)

The 855X had a planar based around the 80386SX or 80386SLC CPU. The newer 955X system were 486SLC2/SLC3 based. The first 9576 and 9577 systems used the same system board known as "Bermuda" (built-in SCSI). The later 9576/9577 i/s systems used a different board - called "Lacuna" (built-in IDE) and were available in two different clock speeds - 25 and 33 MHz.

The 76s/77s systems were the same as the 76i/77i units but they were equipped with a (modified) Future Domain SCSI card, to handle internal/external SCSI devices.

These models used the following riser cards (largely non-interchangeable):

Type# SlotsPart DescriptionFRU P/N
8556
(386SX/SLC)
3x 16-bit
(1x AVE)
Bus adapter79F7210
Bus adapter/speaker support79F7213
8557
(386SX/SLC)
5x 16-bit
(1x AVE)
Bus adapter riser type 185F0056
Bus adapter riser type 241G3877
plus adapter support guide92F0042
9556
(486SLC2/3)
3x 16-bit
(1x AVE)
Bus adapter79F7210
plus bus adapter support96F7769
9557
(486SLC2/3)
5x 16-bit
(1x AVE)
Bus adapter riser card41G3877
plus adapter card guide96F7758
9576
("Bermuda")
3x 32-bit
(1x AVE)
(1x BVE)
Bus adapter87F4833
plus bus adapter support96F7777
plus card guide/speaker assembly92F0244
9577
("Bermuda")
5x 32-bit
(1x AVE)
(1x BVE)
Bus adapter riser card87F4836
plus adapter card guide92F0042
9576 i/s
("Lacuna")
3x 32-bit
(1x AVE)
Bus riser assembly68G2706
plus card guide92F0244
plus card guide assembly C292F0243
plus bus adapter support71G5711
9577 i/s
("Lacuna")
5x 32-bit
(1x AVE)
Bus riser assembly68G2709
plus card guide92F0042
plus card guide assembly C296F7758

Note: The CMOS battery (CR2032) is located on the riser card for all listed systems.

So you see, it is important to know both the part number and clock speed limitation of the Lacuna-type board, and to have the correct bus riser card for the particular box/system board. In other words, you cannot really upgrade a 76/77 to a 76/77 i/s without changing the riser card as well as the system board!


Unit Does Not Turn On (9556/57 9576/77)

Certain (Premium Line) models 9556, 9557, 9576 and 9577 have a security switch and will not run with the cover removed or if there is some problem with the security switch. The switch is built into the front of the base unit and interrupts the power supply. It's easy to find - it is blue and sits somewhere left from the disk-drive bay.

It can be pushed with the finger gently upwards and to the inside - and the machine *should* run fine even without the case cover. No need to be afraid, both the power switch as well as the security switch operate at low voltage. They switch only a weak +5 V power-on line, not mains voltage.

But watch out, sometimes the security switch flips back after some time or when you accidentally bump into the system. When that happens the machine powers off.

The switch can break if the machine's cover is installed carelessly. If you are experiencing a machine, which does not power on, inspect this switch first, before you begin replacing other parts.


PCMCIA Adapter Mounting

I finally got around to installing the PCMCIA adapter in my 77s. The trick- mount the adapter on a 76/77 floppy tray. (Adapter MUST be in the stamped metal bay PN 64F1270) Remove the rail guides on the dive support structure in the 77. (Catches are on the inner end) swap the guides to the other side and push them onto the mounting studs. Now turn the tray/adapter upside down and push it into the rails. Note that the two card ejection buttons are now on the left side of the adapter. Just happens to be the exact height to perfectly fit the bezel.

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: 09 Dec 2024 - Changelog | About | Legal & Contact