I think my power supply is dead

  • Thread starter Thread starter Cyde Weys
  • Start date Start date
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Cyde Weys

Last night, in the middle of a game, my computer just went dead and
refused to boot up. I think the problem may be the power supply (450W,
made by "Rhycom" if you've ever heard of them). I've removed the power
supply from the case and tried plugging it in and nothing happens. I
just want to confirm my theory that the power supply is dead: regular
power supplies, when disconnected from everything but power, should
still at least whir up their fans, right? Or does the power supply need
ot be attached to the mobo for the fans to work (in which case it may
not be my power supply that's dead?)

Thanks a lot for the help.

P.S. And no, I'm not stupid, I made sure the switch was on the "on"
position and the circuit set to 110V but still, nothing happened.
 
It takes less time and would have taught more by not removing
supply AND using the so important 3.5 digit multimeter.

Procedure: Motherboard turns power supply on and off. But
controller circuit requires power. When power supply is
plugged into wall receptacle, then purple wire (from power
supply to motherboard) provides 5.0 volts (within limits of
chart).

When power button is pressed, then motherboard controller
tells power supply to power on. Green wire is above 2.4 volts
when power supply should be off. Green wire should measure
less than 0.7 volts when power button is pressed - to command
power supply on.

Three components - power supply, motherboard controller, and
power switch. Using meter, discover which is or is not
working. Only then were you ready to replace something.
Voltage Wire Color Min V Max V
+5 V Red 4.75 V 5.25 V
-5 V White -4.75 V -5.25 V
+12 V Yellow 11.4 V 12.6 V
-12 V Blue -11.4 V -12.6 V
+3.3 V Orange 3.135 V 3.465 V
+5VSB Purple 4.75 5.25
!Power On Green 0.8 2.0
Power OK Gray >2.4 when power is good

BTW, if you did not pull plug from wall receptacle before
removing supply, then motherboard failure is a new
possibility.
 
w_tom said:
It takes less time and would have taught more by not removing
supply AND using the so important 3.5 digit multimeter.
Click to expand...

I don't have one of those - how much would it cost, where could I get
one, and which do you suggest? And how exactly would I use it -
attaching one lead of the multimeter to the little metal contacts in the
wires coming out of the PSU and the other lead to ... where?
Procedure: Motherboard turns power supply on and off. But
controller circuit requires power. When power supply is
plugged into wall receptacle, then purple wire (from power
supply to motherboard) provides 5.0 volts (within limits of
chart).

When power button is pressed, then motherboard controller
tells power supply to power on. Green wire is above 2.4 volts
when power supply should be off. Green wire should measure
less than 0.7 volts when power button is pressed - to command
power supply on.

Three components - power supply, motherboard controller, and
power switch. Using meter, discover which is or is not
working. Only then were you ready to replace something.
Voltage Wire Color Min V Max V
+5 V Red 4.75 V 5.25 V
-5 V White -4.75 V -5.25 V
+12 V Yellow 11.4 V 12.6 V
-12 V Blue -11.4 V -12.6 V
+3.3 V Orange 3.135 V 3.465 V
+5VSB Purple 4.75 5.25
!Power On Green 0.8 2.0
Power OK Gray >2.4 when power is good

BTW, if you did not pull plug from wall receptacle before
removing supply, then motherboard failure is a new
possibility.
Click to expand...

No, I definitely always totally unplug everything from my box before
opening it up and screwing around with the insides. Also, the physical
location of my box (on a high shelf above my desk) and its length from
the power outlet makes it a near physical impossibility to work on the
machine while it is still plugged in.

By the way, thanks for the quick and thorough reply. I'm going to get a
new power supply this weekend anyway - if it fixes the problem, great,
if not, I can stick it in one of my other machines that I think may be
suffering from less current.
 
Last night, in the middle of a game, my computer just went dead and
refused to boot up. I think the problem may be the power supply (450W,
made by "Rhycom" if you've ever heard of them). I've removed the power
supply from the case and tried plugging it in and nothing happens. I
just want to confirm my theory that the power supply is dead: regular
power supplies, when disconnected from everything but power, should
still at least whir up their fans, right? Or does the power supply need
ot be attached to the mobo for the fans to work (in which case it may
not be my power supply that's dead?)

Thanks a lot for the help.

P.S. And no, I'm not stupid, I made sure the switch was on the "on"
position and the circuit set to 110V but still, nothing happened.
Click to expand...

Ummm, i recommend you break your policy about opening it, and open it.

Check the fan, see if it's siezed... IIRC they used crap
sleeve-bearing fans. It's a junk power supply, but, LOL, you could
probably fix it by replacing the fan and the output capacitors... I
can't be sure that's the problem, but it's by far the most common
failure point on those generics.

To address your question, a power supply needs a load, at least on
it's 5V lead... some have this load integrated as a power resistor,
actually almost all do these days, but who knows what gets cut from
the design when they start minimizing the design cost. In any case,
attaching a hard drive is enough, then when you short the PS_ON, green
wire to ground, it should work, if it will. Note that if it's failed,
the output may be bad, you don't want to be attaching a "good" hard
drive for this test.
 
kony said:
Ummm, i recommend you break your policy about opening it, and open it.

Check the fan, see if it's siezed... IIRC they used crap
sleeve-bearing fans. It's a junk power supply, but, LOL, you could
probably fix it by replacing the fan and the output capacitors... I
can't be sure that's the problem, but it's by far the most common
failure point on those generics.
Click to expand...

I'll check the fan and see if it's seized, but no way in hell am I gonna
screw around with replacing capacitors ... it's just too risky. At that
point I'd just buy a new power supply.
To address your question, a power supply needs a load, at least on
it's 5V lead... some have this load integrated as a power resistor,
actually almost all do these days, but who knows what gets cut from
the design when they start minimizing the design cost. In any case,
attaching a hard drive is enough, then when you short the PS_ON, green
wire to ground, it should work, if it will. Note that if it's failed,
the output may be bad, you don't want to be attaching a "good" hard
drive for this test.
Click to expand...

By shorting green wire to ground, you mean get a short wire and stick it
into the two appropriate square holes in the mobo connector, right?
Does it have to be a hard drive for this purpose - I don't have any
expendable hard drives laying around. I could use an optical drive or a
floppy drive though, will that work?
 
I'll check the fan and see if it's seized, but no way in hell am I gonna
screw around with replacing capacitors ... it's just too risky. At that
point I'd just buy a new power supply.
Click to expand...

Well that's your call, I just mentioned it as the procedure I've used,
which is the most common problem, and solution.

By shorting green wire to ground, you mean get a short wire and stick it
into the two appropriate square holes in the mobo connector, right?
Does it have to be a hard drive for this purpose - I don't have any
expendable hard drives laying around. I could use an optical drive or a
floppy drive though, will that work?
Click to expand...

Yes, with the power supply disconnected from everything but a
worthless hard drive (or substitute your choice of load, an old hard
drive is something easily understood by everyone), use a jumper wire,
paperclip, whatever, to connect pin 14, PS_ON (usually a green wire)
to any ground, either a black wire or the power supply metal casing.

An optical drive should work, but I don't recall the power consumption
of a floppy drive. A "dead" motherboard will usually work too, so
long as it isn't shorted out, or an automobile tail light bulb, costs
about 50 cents at an auto parts store, but requies the odd parts, a
socket or soldering.

The multimeter/voltage meter w_tom mentioned can be found just about
anywhere... a hardware store, possibly Wall-Mart, K-Mart, Radio Shack,
certainly hundreds of places online, etc. It need not be expensive
for the level of accuracy required for this purpose, a cheap $10 unit
will do fine, though these days most people prefer the digital over
the analog type, and they are cheaper to operate in the long run if
they accept AA or 9V battery, not a rarer, more costly size. They run
a long time on a pair of alkaline AA, several years if you don't use
it very often, the shelf life of the batteries would determine their
lifespan.
 
Okay, I did what you suggested and the fan in the power supply whirs for
a fraction of a second, does maybe one rotation, and then dies. This is
repeatable. So what do I do now? It sounds like the power supply is
indeed at fault.
 
Cyde said:
Okay, I did what you suggested and the fan in the power supply whirs for
a fraction of a second, does maybe one rotation, and then dies. This is
repeatable. So what do I do now? It sounds like the power supply is
indeed at fault.
Click to expand...

Okay, I violated my own policy and opened up the power supply. I can't
see anything obviously wrong with it (not that I necessarily know what
I'm looking for). The fan isn't clogged with dust and turns very easily
even when I just blow on it. Anything else I should do before I get me
a new power supply?
 
Okay, I did what you suggested and the fan in the power supply whirs for
a fraction of a second, does maybe one rotation, and then dies. This is
repeatable. So what do I do now? It sounds like the power supply is
indeed at fault.
Click to expand...

To verify, you had a load attached? Many power supplies that need an
external load, would do just that, power on only long enough to stir
the fan, then shut off.

Assuming you did have the optical drive attached, that would indicate
a failure of the power supply. Confirmation would be obtained by
testing it, as w_tom mentioned, taking the voltage readings would be
something I'd advise if you'd had a voltage meter handy. Then again,
I already knew those were junk power supplies, so if spending the
least amount of $ was the goal I'd put the $10 for a voltage meter
towards a better power supply rather than chancing it on that one at
this point. Then again, a multimeter is a handy tool to have, the
more you learn/do/etc, the more likely you'll have another need for
one.

Even if you don't want to repair it, opening it (after unplugged from
AC for a minute or two) will probably reveal what failed... more often
than not there's visual sign of the failed component(s).
 
kony said:
To verify, you had a load attached? Many power supplies that need an
external load, would do just that, power on only long enough to stir
the fan, then shut off.
Click to expand...

Yeah, I had a load attached.
Assuming you did have the optical drive attached, that would indicate
a failure of the power supply. Confirmation would be obtained by
testing it, as w_tom mentioned, taking the voltage readings would be
something I'd advise if you'd had a voltage meter handy. Then again,
I already knew those were junk power supplies, so if spending the
least amount of $ was the goal I'd put the $10 for a voltage meter
towards a better power supply rather than chancing it on that one at
this point. Then again, a multimeter is a handy tool to have, the
more you learn/do/etc, the more likely you'll have another need for
one.
Click to expand...

I'm gonna get a multimeter anyway. It's definitely a useful tool to
have around that no hardware geek should be without.
Even if you don't want to repair it, opening it (after unplugged from
AC for a minute or two) will probably reveal what failed... more often
than not there's visual sign of the failed component(s).
Click to expand...

I opened it and I wasn't able to see anything indicating a failure.
 
I opened it and I wasn't able to see anything indicating a failure.
Click to expand...

Most often you might see large capacitors vented, domed, leaky, or a
spot where a capacitor USED to be but now only some tin-foil looking
stuff... Not the two huge primary capacitors, but the larger gouping
of them about where the power leads connect to the PCB.

Also check for burnt spots around diodes and resistors, and inspect
the MOVs for burn marks or small holes. It may well be that they're
no visable evidence, though if you're going to get the multimeter
anyway you might as well test it before purchasing the new power
supply, unless you're in a rush... sooner or later you will need more
than 250W anyway, if not already... running a unit at max capacity
will decrease it's lifespan.
 
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