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From: waldram@WOLF.UWYO.EDU
Newsgroups: comp.sys.apollo
Subject: 10K power supply problem
Message-ID: <9012070028.AA04240@wolf.Uwyo.EDU>
Date: 7 Dec 90 00:28:52 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 38

FYI:
  DN 10000 owners:
   We have experienced some severe power supply shutdown problems
on our 10K.  Symptoms are:
   1) System loses main power.
   2) Standby lamp on front pannel lit
   3) Error status 30 (HEX) on EuroCard power supply plugged into
      the bottom of the X bus.

   There is a SERVICE NOTE on the +5 V portion of the 10k
power supplies dated 18 June 1990.  A summary of the text follows:

DN100X0/DSP100X0
Serial Numbers: All

Date Code: All +5 Volt Booster Modules with 1988 Date Codes
Performed By: HP/Apollo Qualified Service Personnel Only
Parts Required: +5 Volt, 150W Control Module (APN 010524-001)

Situation:
A problem has been identified with the DN100X0/DSP100X0 power sys-
tems in both Manufacturing and the Field. The power system shuts down
due to a +5 Volt OV (Over Voltage) failure.

Having evaluated several Power EuroCards from Manufacturing and
returns from the field, R&D has identified an oscillation on some of the 
+5 Volt Booster DC/DC Converters.  This oscillation forces the +5V
output voltage to exceed +5.3V dc and the microprocessor shuts down
the power system.

After having tested different +5 Volt Booster Module configurations,
R&D has concluded that Booster Modules with 1988 Datecodes are the
direct cause of the +5 Volt OV (overvoltage failures).

                             -jjw
waldram@grizzly.uwyo.edu
jwaldram@outlaw.uwyo.edu
jwaldram@UWYO.BITNET