Bad PC PowerSupply or MotherBoard?
kenit...@yahoo.com
model etc if anyone wants.
Tested the memory, floppy, CD, and hard drives on another working PC.
Everything works.
Am posting because have yet to test the powersupply and motherboard.
Am a little apprehensive because have heard that can blow a good
powersupply if connect to a bad motherboard. Do not know if can cause
any damage to a good motherboard if connect to a bad powersupply.
Would appreciate any suggestions or tips.
Thanks
Ken
lsmartino
kenit...@yahoo.com ha escrito:
You got it backwards... you can blow a good motherboard with a bad PSU,
but not the other way around. In a properly designed PSU, if the
motherboard is shorted, the PSU will refuse to start, and nothing will
be damaged.
Since all the components you tested are ok, the next thing I would do
is to try a new PSU there.
me
@i39g2000cwa.googlegroups.com:
check the motherboard for bad capacitors, they will likely have bulged tops
(domed instead of flat) or leakage. That is the most likely problem from
the description given.
----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups
----= East and West-Coast Server Farms - Total Privacy via Encryption =----
Puckdropper
> Was given a nonworking Compaq to play with. I can provide the specific
I'd not worry about it too much. If you blow the motherboard, don't
worry, it's a Compaq. (In my experience, Compaqs are only good for parts
machines. They're junk otherwise.)
You can get power supply testers and the like, or simply plug a drive in
to the power supply and start testing output voltages. Also, with the PS
off and unplugged try measuring resistance between supply and ground (+
and -). There should be some resistance, most power supplies that die
are designed to switch every output to ground when they do.
Puckdropper
--
www.uncreativelabs.net
Old computers are getting to be a lost art. Here at Uncreative Labs, we
still enjoy using the old computers. Sometimes we want to see how far a
particular system can go, other times we use a stock system to remind
ourselves of what we once had.
To email me directly, send a message to puckdropper (at) fastmail.fm
kenit...@yahoo.com
lsmartino,
> You got it backwards... you can blow a good motherboard with a bad PSU,
> but not the other way around. In a properly designed PSU, if the
> motherboard is shorted, the PSU will refuse to start, and nothing will
> be damaged.
>
> Since all the components you tested are ok, the next thing I would do
> is to try a new PSU there.
What about repairing the old one? This is a learning project so I
would like to know what killed the original PSU.
Also thanks for correcting my errors.
Ken
Bob Kos
<kenit...@yahoo.com> wrote in message
news:1149373802.0...@i39g2000cwa.googlegroups.com...
You don't indicate symptoms. I'm guessing no power / zero response when
power button is depressed.
You didn't say whether you tested continuity of the momentary power switch.
Wouldn't that be a quick fix? You can follow the wires to the MOBO,
disconnect the switch connector, and jump the two pins on the MOBO
momentarily with a small bladed screwdriver.
An ATX power supply won't start without a ground signal supplied by the
MOBO. If you want to test the power supply, do this... Remove all
connections except 1 drive. Doesn't matter which. You have to leave a load
on it. With the 20 pin MOBO connector in your hand, jumper pin 14 ( light
green ) with pin 13 ( black ). The power supply should start. If it
doesn't, it's broke. If it does, you can perform pinout tests by following
a chart obtainable from a zillion sources by Google-ing 'ATX Pinout'.
My best suggestion is to sub a power supply. That is a quick & dirty test
that usually tells the story. I don't recomment attempting a repair on a pc
power supply for two reasons:
1) They're CHEAP with a capital 'CHEAP'. If you pay yourself only $1 / hour
to repair your existing PSU, you'll still be ahead by simply buying a
replacement.
2) If the PSU went bad once, it is old. It is stressed. You'll repair the
immediate problem but will afford no protection against a different failure
now or later. Remember - they're CHEAP - expense wise and quality wise.
They're all made in China and they work like it.
It would be a shame to have lucked a blown PSU without MOBO damage only to
fix it and have the PSU wipe everything out a month later. They usually
fail with all the fire, smoke, noise and theatrics of a good stage show -
they don't usually just quietly blow a fuse.
Good luck.
miligor
happend. This motherboard (with integrated CPU) was working on old
computer the day before, but today, on the second comp., she don't
(the same PSU). Can mobo colapsed if speaker (beeper) was connected
wrong: pins 1 and 4 are wrong, 3 and 4 are correct. In the first
moment speaker was connected at 1 and 4 (pin 4 is +5V) ???
Bob Kos
"miligor" <n...@spam.invalid> wrote in message
news:yZchg.121196$Mg2....@fe08.news.easynews.com...
you caused failure. If Pins 1 & 2 are for something other than the speaker,
then you'll need to clarify the purpose of those pins for better feedback.
I am guessing that you removed the motherboard from one case and installed
it into another case? If this is what happened, there is a very real
possibility that you have created an open on the mainboard. I have seen
this a number of times. A board is perfectly fine till someone snaps an
additional memory module in, plays with an IDE cable, inserts a PCI card, or
any other operation that causes the board to flex. At that moment, a
circuit buried somewhere in the laminated circuitry that was making contact
through gravity and magic is disturbed, never to find continuity again.
When dealing with PC mainboards, leave sleeping dogs lie!
kenit...@yahoo.com
Bob
> You don't indicate symptoms. I'm guessing no power / zero response when
> power button is depressed.
Correct
> You didn't say whether you tested continuity of the momentary power switch.
> Wouldn't that be a quick fix? You can follow the wires to the MOBO,
> disconnect the switch connector, and jump the two pins on the MOBO
> momentarily with a small bladed screwdriver.
Will Do. If it starts do I immediately remove the screwdriver?
> An ATX power supply won't start without a ground signal supplied by the
> MOBO. If you want to test the power supply, do this... Remove all
> connections except 1 drive. Doesn't matter which. You have to leave a load
> on it. With the 20 pin MOBO connector in your hand, jumper pin 14 ( light
> green ) with pin 13 ( black ). The power supply should start. If it
> doesn't, it's broke. If it does, you can perform pinout tests by following
> a chart obtainable from a zillion sources by Google-ing 'ATX Pinout'.
Just to make sure I have it correct. I remove the MOBO harness and
only leave 1 HD connected, then jumper 13 and 14. If starts PS is OK.
Thanks much for the detailed tips!!!
Ken
kenit...@yahoo.com
"With the 20 pin MOBO connector in your hand, jumper pin 14 ( light
> > green ) with pin 13 ( black ). The power supply should start."
Forgot to ask, what to you use to jumper 13 and 14? Also am guessing
that these 2 wires are low Voltage and Amp so there is No personal
harzard?
Thanks again for the detailed tips!!!
Ken
Bob Kos
<kenit...@yahoo.com> wrote in message
news:1149703222.0...@u72g2000cwu.googlegroups.com...
Yes - remove the screwdriver. It's the same as pressing the button on the
front of the case. Apply the short, then release. The trick part is making
sure you hit the correct pins and ONLY the correct pins.
I use an unfolded paperclip to jumper the two wires together. It is low
power and poses no hazard. If you really want to play it safe, hold the
paper clip in a hand protected with a heavy work glove. Again - make sure
you jumper the correct pins - black wire and light green wire.
kenit...@yahoo.com
Thanks again for the paper clip tip! Jumpered #13 and 14 as you
instructed. When connected the PS power cord to an AC extension cord
heard a faint hi freq sound but no fan sound/movement or hard drive
sound.
To double check I then jumpered a Good PS and again connected the
cords. This time the hard drive and PS fan started.
Guess now is the time to try the Good PS with the Compaq MotherBoard.
Question, what if the Compaq PS when it died damaged the MotherBoard?
Is it worth checking the MotherBoard for shorts etc?
Ken
Bob Kos
<kenit...@yahoo.com> wrote in message
news:1149802114.7...@i40g2000cwc.googlegroups.com...
It's possible that the PS damaged the motherboard. I'm sure there are tests
that you can do as a preliminary. I've never bothered. The only real way
to know is to hook it up and let it fly. My bet is that it will fire up and
run fine. 99% of the time they do. If the board is blown, you'll cause no
further harm by hooking up a good power supply. It's already junk. The
board won't likely hurt the power supply.
kenit...@yahoo.com
Bob Kos
> It's possible that the PS damaged the motherboard. I'm sure there are tests
> that you can do as a preliminary. I've never bothered. The only real way
> to know is to hook it up and let it fly. My bet is that it will fire up and
> run fine. 99% of the time they do. If the board is blown, you'll cause no
> further harm by hooking up a good power supply. It's already junk. The
> board won't likely hurt the power supply.
Finally put tried it. Guess I got the 1% because when turned it on,
the hard drive and CPU fan started but the monitor screen was dead.
Also there were no beeps or any soundswhen started. This MoBo has
internal graphics so decided to install a real PCI graphics card. Same
thing.
Guess the only thing left to test is the CPU. Am wondering what is the
% that the CPU works when the power supply damages the MoBo?
Ken
Bob Kos
<kenit...@yahoo.com> wrote in message
news:1149982767.4...@f6g2000cwb.googlegroups.com...
Do you know that the replacement PS is good? I suspect that it is, but I
got burned that way once so it comes to mind.
It does sound as if the mainboard is bad. I have seen bad motherboards take
out processors on two occasions. they were both AMD Athlon machines. I
don't know that the Athlon being both instances is relevant. I have seen
twice where boards took a lightning hit in through the AC line & out the
modem / phone line without damage to the processor. Those machines were
both Pentium I machines. Both smoked the motherboards & power supplies. As
such, I think it's a difficult call without knowing EXACTLY what went bad on
the board.
Unfortunately, you are now in the position of having to access another
machine to test your processor. What kind of processor is it?
One other free thing to try. And I don't know why this has worked for me
but it has. Clear the CMOS. Take the battery out and apply the CMOS clear
jumper. Then put everything back and see what happens. The CMOS may have
been scrambled by some sort of overcurrent condition that happened when your
PS went bad.
And as I have just found recently, don't forget to look for bulging ,
leaking, or otherwise deformed capacitors. The PS failure might have been
enough to push a marginal cap over the edge. Apparently there was a rash of
defective electrolytics that made their way onto mainboards a few years
back. I just opened a board up with 13 leaky / bad caps.
kenit...@yahoo.com
> Do you know that the replacement PS is good? I suspect that it is, but I
> got burned that way once so it comes to mind.
There have been 2 PSes tested with this MoBo. One was a New Compaq and
other a New std ATX PS neither started the MoBo.
> It does sound as if the mainboard is bad. I have seen bad motherboards take
> out processors on two occasions. they were both AMD Athlon machines. I
> don't know that the Athlon being both instances is relevant. I have seen
> twice where boards took a lightning hit in through the AC line & out the
> modem / phone line without damage to the processor. Those machines were
> both Pentium I machines. Both smoked the motherboards & power supplies. As
> such, I think it's a difficult call without knowing EXACTLY what went bad on
> the board.
My question is how to find what went bad with the MoBo?
> Unfortunately, you are now in the position of having to access another
> machine to test your processor. What kind of processor is it?
Maybe I am Lucky on this, it is an Intel Celeron.
> One other free thing to try. And I don't know why this has worked for me
> but it has. Clear the CMOS. Take the battery out and apply the CMOS clear
> jumper. Then put everything back and see what happens. The CMOS may have
> been scrambled by some sort of overcurrent condition that happened when your
> PS went bad.
Thanks for the CMOS tip will try! If you remove the battery will the
CMOS clear itself? This Mobo had been without a battery for a couple
of months before I got the PC.
> And as I have just found recently, don't forget to look for bulging ,
> leaking, or otherwise deformed capacitors. The PS failure might have been
> enough to push a marginal cap over the edge. Apparently there was a rash of
> defective electrolytics that made their way onto mainboards a few years
> back. I just opened a board up with 13 leaky / bad caps.
I have looked but so far have not seen any leaky or bulging caps. Am
wondering if the caps may be bad but at this time am not too anxious to
pull all the caps just to check.
Ken