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H006547 SYSTEM WILL NOT POST (POWER-ON SYSTEM TEST)
Note:
This tip is to be used only in unusual situations
where routine problem determinations methods have
failed. This procedure might be better utilized in a
"service shop" type environment.
Symptom:
POST will not run. The
monitor screen is blank. There is no audible or
visual signals. Multiple FRU replacements, including
the system board, have failed to fix this "dead
system."
At this point, all HMM (Hardware Maintenance Manual)
service procedures and "Undetermined Problem" steps
should have already been taken.
The following procedure has proven effective in
isolating "dead system" problems that have not been
resolved by the established service procedures:
"Bread-board*" the system, using the following
procedure:
1. Remove system board, power supply, base memory,
diskette drive and cable, etc. from system unit
cabinet.
2. Re-assemble the basic ** system outside the
cabinet, on a non-conductive surface, using care to
prevent individual parts from coming into contact
(shorting against each other).
Note:
A. DO NOT
place system board on top of an ESD mat or the foam
used to pack FRU parts. The ESD mat is
CONDUCTIVE. Some foam (pink & black) used to
pack FRUs is treated with a conductive agent to
protect parts from ESD (Electro-Static Discharge).
[Ed. Tom:
ESD dissipative mats are effectively non-conductive - well, to
be more precise they are conductive, but their resistance is
somewhere in the megaohm - gigaohm range when measured with a
large surface electrodes, so high that you probably won't even
be able to measure it with your multimeter and normal probes.
So it's perfectly fine to use them as a work surface for your
tests and measurements.]
B.
Cardboard, linoleum or a tile floor is acceptable to
support system board. (Be aware, the bottom side of a
system board may scratch wooden office furniture, and
some "black" cardboard may be conductive!)
3. Turn on system power and observe system for signs
of POST activity (cursor on monitor, memory count,
activity lights flashing, or audible sound).
A. If
system POST runs correctly, inspect interior of
cabinet or anything that might be touching the
backside of system board. Look for bent ESD/RFI
shields, loose foreign objects, screws, or even tiny
slivers of conductive paint near screw heads.
B. If
system still fails to run POST, escalation of problem
through hardware support structure is recommended.
Yeah. Updated version, ask on
comp.sys.ibm.ps2.hardware for help if you haven't done
so at the start!
* "Bread-boarding" refers to
assembling an electronic device without a cabinet or
other enclosure. This procedure is routine
during development of a product to prove that a given
design is functional.
The advantage of
this process is:
1. It provides
visibility to areas that are not easily seen inside
the cabinet.
2. It allows easy
access to all the functional system parts.
** Note: It is
presumed that all optional adapters have been removed
from the system during this process and the system is
at a MINIMUM configuration to run POST and provide
audible and visual indications of system activity.
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