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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 FRU 75H9141
IPB Bridge card
- use 33Mhz PCI bus clocking Date of 95
J3-6 Outlines only
JP1 Primary / Secondary Bridge
JP2 Program Enable |
U1 Corollary PCIB 94C105A
U3 75H7487
1 |
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 FRU 76H7134 Date
of 94
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)
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).
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| C-BUS II PCI BUS BRIDGE
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| ASSY __________
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| MADE IN U.S.A.
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C66 C67
Some bridge cards were undercut at the EMC
shield attach point which could cause a short to the C66 capacitor.
SUBJECT: INTERMITTENT HANGS - SERVER PC720(8642)
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 Part Number 71G0694) requires J24 on the system
board to be open circuit
Bridge card 75H7667 (fru Part Number 71G0694) requires J24 pins 1+2
to be Short circuit ( ie. 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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