PCI Bridge Card

Introduction
PCI Bridge Card New
PCI Bridge Card Old
Bridge Card EMC Shield Causes System Hangs or Failure to Boot
Intermittent Hangs


Introduction

The multiprocessor bus-to-PCI bridge is a special adapter that physically plugs into two sockets, one on the multiprocessor bus and one on the PCI bus. The circuitry on this card controls the movement of data between the processor complexes, memory cards and the I/O adapters on the Micro Channel and PCI buses. It implements a split bus design so that during slower I/O operations the multiprocessor bus can be made available for processor to memory transfers without having to wait on the I/O transfer.


PCI Bridge Card New ('95) FRU P/N 75H9141, IPB Bridge card

Use 33 MHz PCI bus clocking.

J3-6 Outlines only 
JP1 Primary / Secondary Bridge 
JP2 Program Enable
U1 Corollary PCIB 94C105A 
U3 75H7487 

JP1 is a three pin header. 1-2 is Primary bridge. 2-3 is Secondary bridge. 
JP2 is a two pin header


PCI Bridge Card Old ('94) FRU P/N 76H7134

CR2 Outline for LED
CR3 LED
JJ1 Primary / Secondary Bridge
J3-17 Outline for headers
U1,2 Corollary DPX 94C101B
U3 Corollary CBC 94C102B
U4,6 PALs
U5,21,24 PALs
U12 1009-05
U13 1019-03
U14 1020-03
U15 1021-03
U16 1011-09
U17 1013-13

JJ1 Primary 1-2 (bottom) Secondary 2-3 (top)


Bridge Card EMC Shield Causes System Hangs or Failure to Boot

Symptom

The PC Server 720 (8642) hangs or fails to boot.

Fix

Inspect the EMC shield on the bridge card. Locate the metal clip (one of four) on the component side near capacitor C66. If the clip appears too close to capacitor C66, remove the EMC shield, and cut out the corner of the metal clip to increase the clearance from the capacitor (Recommended)

-OR-

Remove the EMC shield, and insulate the edge of the metal clip with electrical tape, and re-install the shield (Alternative).

 --------------------------------------------------------------
| C-BUS II PCI BUS BRIDGE                ____   ____   ____    |
|   ASSY __________                     |    | |    | |    |   |
|     MADE IN U.S.A.                    |    | |    | |    |   |
|                                       |    | |    | |    |   |
|                                        ----   ----   ----    |
|                                        ____   ____   ____    |
|                                       |    | |    | |    |   |
|                                       |    | |    | |    |   |
|                                       |    | |    | |    |   |
|                                        ----   ----   ----    |
|     ____   ____   ____                                       |
|    |    | |    | |    |                                      |
|    |    | |    | |    |           ---  ---  ---  ---  ---    |
|    |    | |    | |    |          |   ||   ||   ||   ||   |   |
|     ----   ----   ----       _ _  ---  ---  ---  ---  ---  __|
-------------------------_____|_|______  ---   ---   ---   |
 |||||||||||| |||||||||||     | |      ||||| |||||||||||||||
 ------------ -----------     | |      ----- --------------
                             C66 C67

Some bridge cards were undercut at the EMC shield attach point which could cause a short to the C66 capacitor.


Intermittent Hangs

Symptom

Intermittent hangs / traps on Server 720 / 8642

Problem Isolation Aids

Check settings of jumper J24 on system and manufacturing part number of PCI bridge card.

Fix

Bridge card 07H1107 (FRU P/N 71G0694) requires J24 on the system board to be open circuit.

Bridge card 75H7667 (FRU P/N 71G0694) requires J24 pins 1+2 to be Short circuit (i.e. the 2 pins of J24 nearest the back of the machine.)

Reason

J24 pins 1+2 S/C sets the PCI bus speed to 33MHz. (new Bridge card)
J24 pins o/c sets the PCI bus speed to 25MHz. (old Bridge card)

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Last update: 30 Sep 2022 - Changelog | Legal Info & Contact