The situation is:
Pent II, ATX, complete quite (not even the power supply fan). Yesterday
it was fine, turned off as usual, and this morning dead as dead can be.
Correct me if I'm wrong, but as far as I understand the purpose of the "on" switch in the front of the case is just to give the power
supply momentary pulse of 5 volts from pin 9 of the big ATX connector (+5VSB) to pin 14 (PWR-ON), connected via the mother board and the
"On" switch. Are there any other components on the mother board
involved with just to turn on the power supply?
Now, the power supply is out of the comp, a "known as good" CD drive
connected for load, there is 5 volts on pin 14, and
with a momentary tuch (short) of pins 14 and 9 still nothing,
no movement of the fan and no signal on "PWR-Good" pin of the
big connector.
What have I done wrong? How can I be sure it's the power
supply failure and not of the mother board if I don't have any
spare, good unit to install?
I have a good reason for suspecting the CPU fan failure just before it happened - stuck and full with dirt, hard to turn by hand. Can it be a reason for the unit falure?

Well if the CPU fan was full of dirt and debri I would pretty much say you fried it.No fan! No CPU ! No system. http://www.PCGuide.com/ubb/eek.gif http://www.PCGuide.com/ubb/frown.gif

PII run alot cooler than todays high speed CPUs, I've heard of a PII surviving quite sometime without a fan...

But if you had nothing from the PSU, no fans, no drives, no lights (?), then I would say dead power supply.

You can checkit by leaving it plugged into the motherboard and powering on, and checking the voltages at the connector, if you have no voltage at all then according to my favorite TV doctor...It's dead, Jim.

Some power supplies have an internal fuse that could have blown (some have a fusable link), when the PCU fan went south. Protecting both your CPU and everything else but potentially scrapping the PSU (nice to have a selfless piece of hardware, huh?), if you can't find the fuse. ($30 PSU all over a 3¢ fuse)

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mjc
Links list:Computer Links (http://www.dreamwater.org/tech/mjc/index.htm)

Celts are the men that heaven made mad, For all their battles are merry and their songs are all sad.

Thanks for the reply. Sorry, please accept my apologies for opening
a new topic instead of replying here - a newbie mistake.
1. let's say the CPU is dead due to over heating, still the
PSU should have been turned on and I still
could get some reaction from it - if only the "power led" on the front panel. Am I right?
2. What about the process of checking the PSU, by taking it out
and having 5 volt from the +5VBS pin connected for a
moment with the PWR-ON pin of the big connector. Was it the
proper way or do you suggest any other form of testing
the PSU when it is out of the comp? (except of course then taking the PCB out and checking every diode, transistor, capacitor etc ).

Even if the CPU was you should get some indication of life from the power supply...even if it were just a LED somewhere.

The recommended way to test the PSU, without a tester, is to leave it attached to the motherboard and check the voltages at the connector (if you have a pin-out diagram of an ATX connector this is pretty easy to do). Just grab a multimeter and insert one lead into a ground and the other into the one you want to check...

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mjc
Links list:Computer Links (http://www.dreamwater.org/tech/mjc/index.htm)

Celts are the men that heaven made mad, For all their battles are merry and their songs are all sad.

Thanks, that was my thought too, and still with no responce, but as far as I understand the ATX PSU has to have some signal in order to start
(http://www.pcguide.com/ref/power/sup/func_SoftPower.htm)
and this is what happaning when pressing the "on/off" switch of the computer (signal of a momentary square wave, +5V, to "PWR-ON" pin, which acts as a "situation changer").
This is why, after id the connector pins (http://www.pcguide.com/ref/power/sup/parts_Motherboard.htm) I disassembled it out and tried to make a short signal from the +5VBS pin to PWR-ON pin. The load imitation was a good CD drive. The results was the same as when it was in the computer i.e. nothing. The only reading I have is the presence of the +5VBS on pin 9.
Please let me know if I got the idea wrong, considering English is not my native tongue...
If you think I've done something wrong in the way of checking the PSU please let me know.

Hi Cat_man,
Sounds like your testing correctly, and it sounds like the PSU is dead.
One question, have you tested power at the outlet the comp is plugged into?
If the CPU fan is that full of stuff what does the PSU fan look like?
Is it possible the "hard switch" on the back of the comp got turned off?
OK OK, I know, thats 3 questions http://www.PCGuide.com/ubb/biggrin.gif . I can get carried away sometimes

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If I tell you to think for yourself, then you're not doing it.
.
.
This is not directed at those asking questions in order to gain knowledge. That shows you are thinking.

Bassman,
Thanks for the reply. The 220 volt AC (Israel, not US...) is o.k. and, as I wrote before, I have the 5 volt DC on the +5VBS pin. If you think that the checking procedure was proper so then it seems that the PSU has passed to the better side...
The main confusement was the way of making the PSU to start when it is out of the computer (on my bench....).
The remark about the UPS fan was to determine whether the fan failure (very hard to turn by hand due to dirt/poor quality, released and functioning after cleaning) culd have caused the burnout of the power suply. Mechanical load on the bearing could cause electrical overload.
If you agree with the checking procedure then I think you are right.
I didn't want to throw away money (about 45-50 US$ here) on the new PSU
before checking it out, because it is a voluntary work I do for animal welfare non-profit organization (www.cats.org.il).
Thanks again.
p.s.
I hope that it is not against any forum's rule to mention the URL.
I hope my English was not much of an embarrassment...

Sounds good...and after a little more checking I came up about the same thing bassman did.

And as to URL...many of us have either our own sites/work sites or favorite site in our sigs.....

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mjc
Links list:Computer Links (http://www.dreamwater.org/tech/mjc/index.htm)

Celts are the men that heaven made mad, For all their battles are merry and their songs are all sad.

Hi Cat_man
As for your English, It is better than some of the people from the US that post here http://www.PCGuide.com/ubb/biggrin.gif http://www.PCGuide.com/ubb/tongue.gif
Back to the PSU. If you have 5v at one pin, you may not have adiquate power at other pins. Can you swap it with the PSU in the machine you are using?? Or try a different softswitch from another machine.
The best place to test all the pins is with it attached to the mobo where the proper loads can be reached.
Good luck and keep us posted

------------------
If I tell you to think for yourself, then you're not doing it.
.
.
This is not directed at those asking questions in order to gain knowledge. That shows you are thinking.

Just wanted to thank you all for your help.
Apparently it was the PSU unit but the CPU is dead as well.
(motherboard o.k. but I can't get another slot 1 old/used CPU here)
well, it looks like a good time to get rid of
that P-II with it's slot 1.
I think that for normal office work and some internet surfing
a celeron with 128 Mb ram, on a simple 370/via mobo
is quite enough - my new donation to the: www.cats.org.il (http://www.cats.org.il)
(the privilege of being retiree - lot of time for such things....)
Thanks again for your help.

Sorry to hear that it was fried cat_man but maybe time for new after all the trouble you've had, Me thinks I need to go under the hood and clean & check mine.Again sorry And your English is just fine. http://www.PCGuide.com/ubb/wink.gif

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What have I gotten my self Into now (ROFLMAO)

[This message has been edited by YODA74 (edited 09-23-2001).]