What are the chances of receiving a new defective power supply.

Hi Guys,

I'm trying to get my girl friend's computer up and running. I'm
dealing with an HP 8765C. A few weeks ago I turned it on and it made a
loud pop. After that attempting to start the unit resulted in no
response. I made sure my UPS was putting out power etc.

I did a little research and the popular consensus was that the power
supply had died. I checked the power supply by jumping the green and
black wires on the mother board connector. Nothing happened (no fan)
indicating a dead power supply.

I ordered a new Thermaltake power supply, installed it and again
nothing happened. I tested it according to Thermaltake instructions.
Same thing, nothing happened.

This is my first time at dealing with a dead power supply. It seems
unlikely that I would get a dead one right out of the box. Am I
overlooking something? Any advice would be appreciated.

Thanks

Don

 

Troubleshooting the hardware problems which include the mobo and PS need
to be done very very carefully, or you will misdiagnose.

This is the part where you need to prove what you did to prove that.

You aren't done yet.

Having a 'spare' PS is a good thing to already have when you are at
troubleshooting step 1 above.

There are a lot of good sites. Here's an example of a 'pretty'
flowchart graphic and some useful words as well
http://www.fonerbooks.com/power.htm Flowchart for ATX Power Supply
Repair

Those guys are trying to sell a book. Some people like what you find at
pcguide http://www.pcguide.com/ts/x/comp/power.htm Troubleshooting
Power Sources and Power Protection Devices

.... plus pcguide is great for a lot of PS fundamentals in a different
section.

 

Thanks Mike,

I appreciate the info.

 

Loud pop, look for a blown capacitor.

 

Is popular consensus based on technical knowledge or just what is
easiest to replace?

The power supply system is more than just a power supply. Do you
keep replacing parts until something appears to work? That is called
shotgunning - what is common among the 'popular consensus'. If a car
mechanic diagnosised that way, he would be quickly unemployed. In
but two minutes, you could have known what is bad using the procedure
in "When your computer dies without warning....." starting 6 Feb
2007 in the newsgroup alt.windows-xp at:
http://tinyurl.com/yvf9vh

Especially important in your case are numbers from the green, gray,
and purple wires before and when power switch is pressed.

Popular consensus says the green to black wire jumper identified a
power supply good or bad. First, some supplies will not start this
way without a load. That is unique to each power supply design.
Second, a power supply can still be defective and yet power when
disconnected from computer and using that green to black wire jumper.
The jumper can only provide a 'maybe' answer.

The only useful answer is one that provides a definitive answer.
That is the multimeter, disconnecting nothing, and two minutes.

Finally, the procedure also provides numbers. Your replies will
only be as good as the information provided. To get more useful
replies from those who actually know what is inside the entire power
supply 'system', post those numbers here.

Demonstrated is the meaning of a popular phrase, "Don't work harder;
work smarter".

 

<Nothing for the 100th time.>

*plonk*

 

Thanks for the helpful reply. I'll take some measurements and post
them.
For what it's worth, I have spent about seven hours or so researching
this problem and this is the first time anyone has pointed my in this
direction. The vast majority of the places I have checked including
the manufacturers' site just suggest jumping the green and black and
watching the PS fan.

 

| Hi Guys,
|
| I'm trying to get my girl friend's computer up and running. I'm
| dealing with an HP 8765C. A few weeks ago I turned it on and it made a
| loud pop. After that attempting to start the unit resulted in no
| response. I made sure my UPS was putting out power etc.
|
| I did a little research and the popular consensus was that the power
| supply had died. I checked the power supply by jumping the green and
| black wires on the mother board connector. Nothing happened (no fan)
| indicating a dead power supply.
|
| I ordered a new Thermaltake power supply, installed it and again
| nothing happened. I tested it according to Thermaltake instructions.
| Same thing, nothing happened.
|
| This is my first time at dealing with a dead power supply. It seems
| unlikely that I would get a dead one right out of the box. Am I
| overlooking something? Any advice would be appreciated.
|
| Thanks
|
| Don

When assembling a computer, attaching power cable to floppy drive, it
sometimes happens that plug is misaligned, connecting only two of the three
pins.. This will fry the PSU (but may not result in a loud pop).

 

No load must damage a properly designed supply. Even the earliest
Intel specs for power supplies listed a minimum size for the wire to
short together all outputs - and no damage. However with so many
computer assemblers who do not even know how electricity works, then
some manufactures have even increases profits by 'forgetting' to
include essential functions inside that supply.

If a misguided power connector causes a power supply failure, then
the damage is directly traceable to a misguided human. These power
supply requirements of no damage were standard long before PCs even
existed.

How poor is electrical knowledge among the 'computer literate'?
Even an A+ Certified Computer Tech need not know how electricity works
to be certified - need not know what has long been standard for power
supplies..

 

It's very possible that you have one or more blown capacitors on the
motherboard. Look for metal cans with shrink-wrap labels, and if the end
shows a crusty deposit or is actually blown open... that's your problem.

 

That can't be a good thing! I'll take a look at it tomorrow. If
the mother board is kaput I suppose I can't complain too much. We have
been using this computer for seven years or so and this is the first
mechanical failure.

I still need to dig out my voltometer and check the output of the PS.
It gets dark so darn early I have a hard time finding anything in my
tool shed.

Thanks