On 21 Jan 2004 18:00:48 -0800, (jbr) wrote:

I appreciate the feedback from all.

Yes Steve I have checked the MB for this setting. The "Keyboard Power
On" setting is/was disabled.

Ok, Thank you. There is a continuing discussion elsewhere in this
thread about how it is "not possible" that keyboard power can kill a
power supply, however that is precisely what has happened to me and is
the experience of a computer shop I'm associated with. Since it's not
primary power but rather a separate always-on circuit it might not be
subject to the same overcurrent protection as the main system, but is
still an essential part of the overall regulation.

Speaking of which, many motherboards were equipped with 1000 and 1500
mfd capacitors that used a defective electrolyte that overheated and
popped the can or let the cap short out. While a shorted capacitor
would generally not allow the supply to start, and a leaky one would
fail leaving a mess long before it would affect the supply, it is
worth making sure that there are no visibly damaged large-value
capacitors on the M/B.

Yes, use a UPS or filterchoke on the mains supply...

Finally, I had a PII (AT) that went through 4 power supplies in one
year. I never found a problem other than just plain bad luck. The
last supply I put in came from a 486, only rated at 175 watts, and
that has lasted for three years so far..

. Such is life..


. Steve ..

By the way the motherboard is/was an ECS - K7AMA (1.5) with a AMD
Athlon Thunderbird 1.4GHz.

In pursuit of a remedy, needed ASAP, today I placed a new motherboard
in the system and brought it back online. I did not have another ECS
so I am using a Shuttle AK39N.

There is much discussion about the AC being "dirty" so as suggested I
may only be treating a symptom. The surge protector that the problem
computer plugs into is shared by a monitor and speakers. Would it be
unusual for only the PC to be effected by the dirty AC?

I will have to double check but I believe the circuit that feeds this
system is surge protected at the panel. Would that prevent the AC
from being dirty?

jbr

I would like to hear JBR say "Yes, I checked the keyboard power
jumper." It may not seem a logical cause for repeated power supply
failure, but that is what actually happens. Until I discovered this
one computer would lose its power supply within two weeks, in one case
the supply lasted about a minute. I finally read the manual,
discovered the jumper, and the system has lasted since 2000. In
another case a store-built clone was losing supplies, when the second
one failed he brought it to me, sure enough keyboard power was
enabled, changed the jumper, and no more failures. Yes using better
supplies would help, but only to provide enough standby current.
That's why I'm chipping in with this suggestion, it doesn't appear
that others in this thread have encountered this issue, or have, but
don't know it.

Step one, check for this jumper, if it exists even, and assuming it's
a PIII, THEN move on to incoming AC. Logical?

Also I don't find that the supplies "degrade" usually it's the zener
shorting, a resistor overheating, or some such.

. STeve ..