MBF COMPANY CONFIDENTIAL FIELD INFORMATION BULLETIN

SERVICE GROUP(S): MICRO                MFG: COMPAQ

 NACS  TYPE(S): 5490,9490              MFG. MODEL(S): DESKPRO 386,
                                                      DESKPRO 386/20

CATEGORY: CPU                          DESC: DESKTOP COMPUTER

                   *** TABLE OF CONTENTS AS OF 12/19/90 ***
FIB 00001.General Information...............................(Text Inco10/27/87
FIB 00002.MULTIPURPOSE FIXED DISK CONTROLLER..........................10/27/87
FIB 00003.POWER SUPPLY FAILURES - PORTABLE 386,III....................10/27/87
FIB 00004.POWER SUPPLY FAILURES.......................................02/24/88


CPU-COMPAQ-DESKPRO 386,DESKPRO 386/20---------------Table Of Contents Pg01 of 01
FIB 00002                                                             10/27/87

                   *** MULTIPURPOSE FIXED DISK CONTROLLER ***

DESCRIPTION

The Multipurpose fixed disk controller board used in the 386/20 is a different
part number from the board used in the older 386 and the 286 machines. The
386/20 maintenance and reference manual indicates that assembly number 000519
can be used in the 386/20. THIS IS INCORRECT. Only assembly number 000336 can
be used in the DESKPRO 386/20.
The correct part numbers are as follows:

   MODEL                COMPAQ PART NO.          NACS  PART NO.

DESKPRO 386/20          113446-001              CZ020023
DESKPRO 386             104174-001              CZ010002
DESKPRO 286             104174-001              CZ010002
PORTABLE II             104174-001              CZ010002


ORIGINATOR: COMPAQ


CPU-COMPAQ-DESKPRO 386,DESKPRO 386/20---------------FIB002 Pg001


FIB 00003                                                             10/27/87


                             POWER SUPPLY FAILURES

PROBLEM DESCRIPTION:

Early production models of power supplies used in the PORTABLE 386 and the
PORTABLE III were designed to dissipate current surges through the power
supply control circuit during a failure.  This results in audible popping
noises as a small, low-power device fails. Some smoke may also be visible.

PROBLEM RESOLUTION:

The condition described above is reported to be alarming to some users, but
is is NOT a hazardous condition.  However, Compaq Computer Corp. recognizes
this condition as undesireable, and has changed the design of the power
supplies.  The new power supply design is incorporated on units with serial  
numbers 1740xxxxxx and above and on spare power supplies with date code
stickers showing x710x and above.


ORIGINATOR: COMPAQ


CPU-COMPAQ-DESKPRO 386,DESKPRO 386/20---------------FIB003 Pg001


FIB 00004                                                             02/24/88

                         *** POWER SUPPLY FAILURES ***

SYMPTOM: POWER SUPPLY HAS SHORT LIFE AFTER REPLACEMENT

PROBLEM DETERMINATION: CHECK THE POWER SUPPLY INSTALLED AND MAKE SURE THAT IT
IS A 192 WATT SUPPLY (COMPAQ # 108065-001,  NACS  # CZ20009).

FIX: IF THE 160 WATT SUPPLY IS INSTALLED THEN IT SHOULD BE REPLACED. BOTH OF
THE 386 SYSTEMS AND THE 12 MHZ 286 DRAW TOO MUCH POWER FOR RELIABLE OPERATION
USING THE 160 WATT SUPPLY. USING THE WRONG SUPPLY CAN RESULT IN PREMATURE SYSTEM
FAILURE.

ORIGINATOR: JOHN HILL


CPU-COMPAQ-DESKPRO 386,DESKPRO 386/20---------------FIB004 Pg001