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Intermittent noisy PC power supply fan

 
 
Brian
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      06-19-2005
Hi all, over the past couple of days my PC's power supply fan (back/top of case)
has been intermittently making "rattling" noises. When this happens, the flow
of air from it is very weak. I've found I can temporarily "fix" the problem by
quickly touching the spinning blades with a piece of paper, whereupon the noise
instantly ceases and the air flow becomes strong and normal again. But then it's
just a matter of time before the noise returns. I can also "fix" it by hitting
the exterior of the case (where the fan is) with a screwdriver. So it seems as
though the fan is just a tad loose or something. The only difference to my PC
lately is the addition of a "chair mat" and the PC's tower is ever-so-slightly
not level now, with the front about 3mm higher than the back (where the fan is).
Is this enough to cause the fan to behave like this (ie. PC not being 100% level),
or is it just a coincidence? I've put a small dinner placement under the back
half of the PC now so see how it goes, but I thought I'd post here anyway for
some feedback/thoughts about it. Thanks!


 
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Brian
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      06-19-2005
Brian wrote:

> Hi all, over the past couple of days my PC's power supply fan
> (back/top of case) has been intermittently making "rattling" noises. When this happens, the flow of air from it is very weak.
> I've found I can temporarily "fix" the
> problem by quickly touching the spinning blades with a piece of
> paper, whereupon the noise instantly ceases and the air flow becomes
> strong and normal again. But then it's just a matter of time before
> the noise returns. I can also "fix" it by hitting the exterior of
> the case (where the fan is) with a screwdriver. So it seems as
> though the fan is just a tad loose or something. The only difference
> to my PC lately is the addition of a "chair mat" and the PC's tower
> is ever-so-slightly not level now, with the front about 3mm higher
> than the back (where the fan is). Is this enough to cause the fan to
> behave like this (ie. PC not being 100% level), or is it just a
> coincidence? I've put a small dinner placement under the back half
> of the PC now so see how it goes, but I thought I'd post here anyway
> for some feedback/thoughts about it. Thanks!


Forgot to mention: Yes, I've opened the case, pulled the power supply
out, cleaned out all dust (there was HEAPS!) and replaced it all, with
everything screwed back nice and tight.


 
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Mike Easter
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      06-19-2005
Brian wrote:
> Hi all, over the past couple of days my PC's power supply fan
> (back/top of case) has been intermittently making "rattling" noises.
> When this happens, the flow
> of air from it is very weak.


Presuming you are absolutely 100% sure that it is the PS fan and not
some other fan like the case fan....

.... presuming that you are sure than it is really clean 'all around' so
that it isn't out of balance from dust grunge, it becomes a matter of
wear or bearings or whatever makes fans stop working right and start
rattling.

It is 'easier' to replace a PS than its fan; but it may be cheaper to
just replace the fan if is removeable and you can find a fit
mechanically and electrically, which will probably require some
soldering. My local parts stores often have such sales on PS/s that a
new [or used] PS might be cheaper than a replacement fan, depending on
the fan and the PS. There's even a used parts store near me that has a
good deal on salvaged PS/s.

Some people are 'demanding' about their choice of fans because they
don't like them to be noisy from 'normal' fan noise


--
Mike Easter


 
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Vanguard
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      06-19-2005
"Brian" <(E-Mail Removed)> wrote in message
news:42b4c000$(E-Mail Removed)...
> Hi all, over the past couple of days my PC's power supply fan
> (back/top of case)
> has been intermittently making "rattling" noises. When this happens,
> the flow
> of air from it is very weak. I've found I can temporarily "fix" the
> problem by
> quickly touching the spinning blades with a piece of paper, whereupon
> the noise
> instantly ceases and the air flow becomes strong and normal again.
> But then it's
> just a matter of time before the noise returns. I can also "fix" it
> by hitting
> the exterior of the case (where the fan is) with a screwdriver. So it
> seems as
> though the fan is just a tad loose or something. The only difference
> to my PC
> lately is the addition of a "chair mat" and the PC's tower is
> ever-so-slightly
> not level now, with the front about 3mm higher than the back (where
> the fan is).
> Is this enough to cause the fan to behave like this (ie. PC not being
> 100% level),
> or is it just a coincidence? I've put a small dinner placement under
> the back
> half of the PC now so see how it goes, but I thought I'd post here
> anyway for
> some feedback/thoughts about it. Thanks!
>
>



You have a worn fan so it out of balance. When it gets sufficiently out
of balance, it will begin to "rattle" and this wobble will slow down the
fan. When you temporarily stop the fan, it starts spinning up again but
has changed its position along the shaft so it is balanced enough to
spin fast but eventually get unbalanced again. For just some minor wear
when the fan makes noise, you might be able to re-oil the fan (remove
the sticker, add a tiny drop of engine oil, and reapply the sticker) but
if it is wobbling enough to slow the fan then it far beyond fixing it
just by adding oil around the bearings. You need to replace the fan.

 
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JANA
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      06-19-2005
The fan should be replaced. The bearings are failing.

You can purchase a fan from most electronic parts suppliers. Some computer
shops also sell a fan that will work in the power supply.

When you open the supply, you should be able to read on the fan, its
operating voltage. The sizes are very standard. You can measure the exact
size with a tape measure.

When replacing the fan, you will have to have some soldering skills, a
soldering iron, a heat gun, and some heat shrink tubing. You will have to
splice in the connectors from the old fan, unless you can have a dedicated
fan for the power supply.

When mounting the replacement fan, make sure that the air flow is in the
correct direction.

The other approach is to remove the power supply, and take it to a shop that
does some electronic device repairs. In this case, the labour cost may be
high in relation to replacing the supply.

--

JANA
_____


"Brian" <(E-Mail Removed)> wrote in message
news:42b4c000$(E-Mail Removed)...
Hi all, over the past couple of days my PC's power supply fan (back/top of
case)
has been intermittently making "rattling" noises. When this happens, the
flow
of air from it is very weak. I've found I can temporarily "fix" the problem
by
quickly touching the spinning blades with a piece of paper, whereupon the
noise
instantly ceases and the air flow becomes strong and normal again. But then
it's
just a matter of time before the noise returns. I can also "fix" it by
hitting
the exterior of the case (where the fan is) with a screwdriver. So it seems
as
though the fan is just a tad loose or something. The only difference to my
PC
lately is the addition of a "chair mat" and the PC's tower is
ever-so-slightly
not level now, with the front about 3mm higher than the back (where the fan
is).
Is this enough to cause the fan to behave like this (ie. PC not being 100%
level),
or is it just a coincidence? I've put a small dinner placement under the
back
half of the PC now so see how it goes, but I thought I'd post here anyway
for
some feedback/thoughts about it. Thanks!



 
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Brian
Guest
Posts: n/a
 
      06-19-2005
Mike Easter wrote:

> Presuming you are absolutely 100% sure that it is the PS fan and not
> some other fan like the case fan....


Yes, it's the PS fan -- as I said, I've touched it and the noise stops,
so that's pretty much proof positive that it's not another fan. The
only other fan I have is the CPU one, and that's noiseless and fine.

> ... presuming that you are sure than it is really clean 'all around'
> so that it isn't out of balance from dust grunge


In a follow-up post I mentioned how I cleaned the fan/PS completely,
so it's not that. Now that my case is 100% level again I'll see how
it goes. It's been a few hours now with no noise, so hopefully that's
all it was. If the noise returns I'll have to look into either oiling
or replacing it, per other recommendations here. Thanks all!


 
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