PSU going bad?

[William J. Lunsford]

My budget home-built PC has worked fine for several years without problems.
Recently, it has acted absolutely dead twice when I have tried to start up -
no fan noise, no beep, nothing. However, after I pulled the plug and
plugged it back in, it started normally both times. There have been no
recent changes to my system. Should I suspect the power supply? I have a
multimeter I can test the power supply with when I get the time. Is there
anything else I should start looking at?



Bill

 

[Cyber Wo]

My budget home-built PC has worked fine for several years without problems.
Recently, it has acted absolutely dead twice when I have tried to start up -
no fan noise, no beep, nothing. However, after I pulled the plug and
plugged it back in, it started normally both times. There have been no
recent changes to my system. Should I suspect the power supply? I have a
multimeter I can test the power supply with when I get the time. Is there
anything else I should start looking at?

Bill

Hi Bill:

I would difinately start there. If your power supply is good then
check to make sure all the connections going to mainboard are good.
The problem mostlikely lies in the powersupply or motherboard.

 

[JAD]

look for bulging capacitors on the mainboard...I have been getting a rash of
P4 N 1.6 era mainboards that are having bulging cap syndrome.

 

[William J. Lunsford]

That's what I was thinking. Thanks for your help!

 

[William J. Lunsford]

Thank you! I'll definitely look for that.

look for bulging capacitors on the mainboard...I have been getting a rash
of P4 N 1.6 era mainboards that are having bulging cap syndrome.

 

[DaveW]

Most likely the PSU is indeed failing. If you replace it, and that does Not
fix the problem, then the motherboard would be the next most likely suspect.

 

[William J. Lunsford]

Thank you for your help!
Bill

Most likely the PSU is indeed failing. If you replace it, and that does
Not fix the problem, then the motherboard would be the next most likely
suspect.

 

[w_tom]

My budget home-built PC has worked fine for several years without problems.
Recently, it has acted absolutely dead twice when I have tried to start up -
no fan noise, no beep, nothing. However, after I pulled the plug and
plugged it back in, it started normally both times. There have been no
recent changes to my system. Should I suspect the power supply? I have a
multimeter I can test the power supply with when I get the time. Is there
anything else I should start looking at?

Most all failures don't even have visual indications. But using the
meter, you can identify the failure even before capacitors start
bulging. Yes, the meter will provide definitive answers in but two
minutes and without shotgunning (changing this and changing that).

First is the voltage on purple wire from power supply to
motherboard. That DC voltage must measure more than 4.87 volts DC
even when computer is off. Next is voltage on green wire. That
voltage must be more than 2 volts and must drop to well below 0.8
volts when power switch is pressed. And last are voltages on any one
of orange, red, and yellow wires. Each voltage must rise within a
second of pressing the power switch and must remain stable above 3.23,
4.87, and 11.7 volts.

Next test the machine by executing (multitasking) to all peripherals
simultaneously - complex video graphics, CD-Rom, disk drive access,
etc. Those orange, red, and yellow wire voltages still exceed minimum
values.

At this point, you should either see the problem or post those
numbers so that a useful reply is obtained. Notice a definitive
answer and no shotgunning. In but two minutes with the meter is
something definitive or numbers that can obtain a useful reply. Even
bulging cap problem or bad connection (and other possible problems not
yet discussed) would be discovered by those numbers.

 

[William J. Lunsford]

Thank you so much for this information. I've seen charts with acceptable
voltage ranges for the various wires, but I have never seen the information
you just provided before.
Your help is appreciated!

Bill

 

[JAD]

those numbers are erroneous, not a 'bad' reference, but don't hold them to
be absolutely correct

 

[w_tom]

Thank you so much for this information. I've seen charts with acceptable
voltage ranges for the various wires, but I have never seen the information
you just provided before.
Your help is appreciated!

Voltage numbers are adjusted for how power supplies fail and for how
a typical multimeter operates. For example, a voltage of slightly
below 4.87 on meter will probably be repeatedly dipping below 4.5 and
causing failure. Provided are numbers observed on the meter so that
actual voltage remains above minimum.

Second, numbers from a meter empower others who would otherwise not
bother to reply because no hard data is provided. Beside being above
minimum, all numbers may also discover other potential problems before
those problems cause failures.

Problem you are now suffering may have been predicted (averted)
months earlier using numbers from a meter. Take meter readings after
replacding a defective part for this same reason - so that future
failures are averted.

 

[Damaeus]

Problem you are now suffering may have been predicted (averted)
months earlier using numbers from a meter. Take meter readings after
replacding a defective part for this same reason - so that future
failures are averted.

Don't you have to stab the wires with a sharp pointy object to get the
readings or is there some kind of special "opening" that you can use?

Damaeus
--
Motherboard Abit Fatal1ty AN9 32X
Processor AMD Athlon 64 X2 4200+ Dual Core
Graphics nVidia GeForce 7950GTOC
Memory 2GB DDR2 800 PC6400
Hard Drives 2x 320GB Western Digital SATA

 

[Ed Medlin]

Don't you have to stab the wires with a sharp pointy object to get the
readings or is there some kind of special "opening" that you can use?

Damaeus
--

You can just insert it into the hole of the molex connector for the
particular wire........

Ed

 

[Valentin]

You can just insert it into the hole of the molex connector for the
particular wire........

...........and if the probe doesn't fit, you can use a piece of copper wire
stripped on both ends: one end attached to the probe, the other will fit
inside the back of the molex connector.
I just did the voltage tests as suggested by w_tom and as a result found the
motherboard to be defective. Asus will send me a replacement, since the
board had a 3-year warranty.

(Greetings w-tom! I have just discovered this interesting newsgroup)

 

[Damaeus]

In "Valentin"

..........and if the probe doesn't fit, you can use a piece of copper wire
stripped on both ends: one end attached to the probe, the other will fit
inside the back of the molex connector.
I just did the voltage tests as suggested by w_tom and as a result found the
motherboard to be defective. Asus will send me a replacement, since the
board had a 3-year warranty.

(Greetings w-tom! I have just discovered this interesting newsgroup)

Nice. I think I'll do some research and get into checking voltages. I
tried to do that once on my car and hated it, but then I hate working on
cars, even though I'm perfectly capable of doing some minor maintenance
work: oil change/filter, spark plugs/wires, air filter, windshield wipers,
air in the tires, etc...

Damaeus
--
Motherboard Abit Fatal1ty AN9 32X
Processor AMD Athlon 64 X2 4200+ Dual Core
Graphics nVidia GeForce 7950GTOC
Memory 2GB DDR2 800 PC6400
Hard Drives 2x 320GB Western Digital SATA

 

[William J. Lunsford]

I finally got around to testing the power supply unit. The voltage on pin 4
was only +1.3, a long way from +5.

I replaced the PSU with a much better one from PC Power & Cooling. So far,
so good.

In case anyone is still looking at this thread, I wish to thank everyone who
responded.

Bill

 

[JAD]

way to go good deal!

I finally got around to testing the power supply unit. The voltage on pin 4 was only
+1.3, a long way from +5.

I replaced the PSU with a much better one from PC Power & Cooling. So far, so good.

In case anyone is still looking at this thread, I wish to thank everyone who responded.

Bill