Re: HP Compaq power supply keeps failing

w_tom <w_tom1@xxxxxxx> wrote:
On Dec 5, 10:02 am, "mark.frase...@xxxxxxxxxxxxxx"
<mark.frase...@xxxxxxxxxxxxxx> wrote:
I hope someone here can help me, I have what I think is a HP Compaq
DC7700 computer at work that keeps blowing power supplies - think I'm
on my 5th or 6th now. The last time it went we decided to try a surge
protector to see if that would help, but less than 3 days after having
the last one replaced it went again today. ...
The 240V mains supply into the room has been checked and found to be
OK, so I'm at a loss as to what's causing them to fail. I did have a
Dell computer in there before running off 110V which failed a few
times, but I put that down to the dusty environment ...

Those who don't know how things work will only blame what they
understand. Many blame dust and heat for failures that are created

the rest say robust robust robust over and over and over again.

dust is an enemy of computers, plain and simple. It coats the parts with
an insulating layet that cannot be cooled efficiently.

increased heat greatly decreases the life of electronic equipment.

So unless you have an old RS/6000 or other tank of a computer the 100
degree dust filled room is a bad idea.

Several points

- heat makes electrolytics capacitors age and dry out faster. Surprise,
they're a major and key component in a power supply.

- heat makes the oil in bearings age and fail faster. Check with any fan
or bearing manufacturer. the life expectancy of small low load bearing is
a function of heat and lubricant aging.

- computer equipment tends to be fan cooled. Bad fans don't cool anything.

Back to the original posting, it sounds as if you have some sort of
serious power issue to be blowing power supplies left and right.





elsewhere. Properly designed computers must work just fine in a 100
degree F room with dust ball inside. Dust does not cause damage. It
may cause a shutdown - a temporary problem. But without sufficient
technical knowledge, a majority will be quick to blame dust rather
than go after technical facts.

They checked the 240 VAC? How? What exactly did they check for? I
can think of numerous anomalies that might cause damage - those who
would check for what using what kind of equipment? IOW you have no
useful answer if OK does not come with 'why' or 'what' is OK. No
'what', 'whys' or numbers means 240 VAC remains a complete unknown.

Best evidence is found in a dead body. IOW what inside each power
supply failed (I must assume power supply failure was actual and
permenant damage due to a shortage of information). Technical
knowledge of how computers actually work is rare among computer
'technicians'. You require someone with electrical and electronic
knowledge to answer a so useful question. Typically neither an
electrician or computer 'board swap' tech will even know what those
interior parts do. Neither typically has sufficient electrical
knowledge. You need the 'rare animal in those breeds' to get a useful
answer.

Assuming that the same problem caused both computer failures (and
that failures are permanently damaged parts - not just repeat failures
solved by swapping supplies), then we move on. Most UPSes will output
at 120 volts something that is two 200 volt square waves even with
200+ volt spikes. Since computer power supplies are so robust, then
even this 'dirty' output from a UPS in battery backup mode cannot harm
them. Notice the numbers. To cause permanent damage to a computer,
line voltage may need to exceed up to 600 volts for a certain time
period. Others will then blame (wildly speculate) dust or old wiring
rather than get (demand) facts. Yes, properly designed power supplies
are that robust (not to be confused with so many clone supplies) can
even withstand voltages that high and higher for short periods without
damage.

So, do you see lights flickering - especially incandescent bulbs
significantly changing intensity anywhere else in the building? All
symptoms are relevant. What does that incandescant bulb do in the
same power receptacle as the computer? What happens to incandescent
lamps elsewhere?

CRT monitor is probably a universal power supply. That means AC
voltage could be anywhere from 90 to 265 volts. Is it? Read the spec
plate. Is that why CRT is even more robust - not damaged? But
again, information is sketchy. Therefore every answer can only
assume. Appreciate why your answers will only be as useful as the
information you provide. What exactly failed in each computer? Why
do you have 240 and 120 VAC in rooms? Of course that means unique and
different AC plugs. What inside that computer component failed? Such
better information means useful replies - without "It could be this
or that ..." phrases. Also means every question here also requires
some type of answer.

Dust and heat would not cause your problems (assuming something has
been permanently damaged). Computers are some of the most robust
appliances in a building. Whatever is causing hardware damage should
be obvious and must be identified before fixing things. Much
information is required which this post only begins asking. Even the
240 volts is completely unknown according to what was posted.
.

Relevant Pages

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