How hard is it?

The fans in my PMG4 AGP are noisy in an unhealthy sounding kind of way.

The case fan looks to be fairly easy to replace so I will probably do so. Although I have read about people replacing the power supply fans I have not found a detailed description of how to open it up. I have seen some people suggest buying a new PC power supply and doing some rewiring but the power supply seems fine so if possible I would rather simply replace the fan.

Any advice / suggestions?

Keep the original PSU but just replace the fans inside . It is not a hard job. Use either the same model fans or those with a higher throughput of air to keep it all cool.Basically a few screws and it comes apart. Bear in mind there is a lot of electricity still inside the PSU even when it is unplugged so be careful. Just touch the parts you have to and no more. I have some links somewhere for taking apart the PSU of a MDD but not a Sawtooth. It shouldn't be too hard to track down via Google though. Sites like XLR8 Your Mac, Macosxhints and MacMods etc should have something. The alternative of course is to get a secondhand one which will go straight in and probably be as cheap as buying two new fans anyway given the availability and popularity of the G4/400's.
Stewie

Catbert: stand by for a PM when i find the guide.

:edit: all you want to do is remove the PSU Cover, unscrew the fan, screw new one and connect wires + tape them up, if you have a soldering iron then soldering it is a good idea.

I'm currently searching for the teardown guide.

Edit: Apple seem to have removed all the teardown guides off the net - if you have too much trouble getting it apart i'll be online tonight and should be able to do make a pictoral guide to removing the psu and fan bracket.

If you can get access to an air compressor, a good shot of air through the PSU will clear out any dust bunnies, then you can re-lubricate the fan without having to open up the unit.

JB

All of the guides are at service.info.apple.com.

How is he supposed to peel back the sticker and lubricate the bearing case through the grille without pulling it apart?

That's all good, but i'm not apple certified and so my apple id is not allowed access.

Thanks one and all

Linux - thanks for the offer but I had the power supply and fan bracket out the otherday to check fan specs etc., so that is not the challenge. I was wondering about getting inside the PSU. It is as simple as undoing the external screws on the PSU and pulling one side of it off?

Is there a way to "discharge" the PSU to make it safer to work with? Anything in particular one should not touch?

try not to touch the capacitors but you should be fine, if you just pull the cable out of the machine instead of shutting it down it should discharge better and the danger is generally very low

It's really as simple as removing the screws and taking the chassis off AFAIK.

The capacitors . I knew it was something inside that could zap you but couldn't remember what it was. I don't know about there not being much zzz's in there though. I seem to recall a few cautionary asides about getting into PSU's .If you know your way around a Voltmeter ( think thats what they're called ) you could test it before working on it.Maybe set up two wires and a bulb to discharge it if you know the pinouts.
Stewie

A little While ago I did the replacement thing, only that I added a little Pc bling by making it a red led fan.
There is really nothing to it, Just pull out the power supply and unscrew the top out. Just be CAREFUL
and try not to tough the contacts on the board (I have been zapped once, and I was lucky)
I have since been told that if you place a metal object across the power leads prongs (obviously while unplugged)
you can get some charge out of the capacitors, but the best rule is not to touch the contacts anyway.

its a little dodgy but here is a link to the one I did,
Yes I repent my pc sin’s.
http://homepage.mac.com/whothebatman/PhotoAlbum14.html

Ha . Hotrodded G4 . Bling Bling !
Stewie

Shorting out the power pins of the power lead will not do anything at all, and you can't get zapped from those prongs - there's a rectifier bridge made of diodes in the way.

You will be fine, you don't even need to remove the board to replace the fan at all, i've pulled psu boards out before without making any effort to discharge them because i've done solder reworking on them and be fine.

Like i said, if you don't shut the machine down and pull out the cord, it will drain the capacitors as it loses power because there's no power to recharge them with, you can also discharge them by shorting the pins of the capacitors with a screwdriver if you are really frightened.

Those capacitors should be avoided IMO. (Basically the electric end of the circuit board is a good thing not to touch even with the power cord out)

Should I call an Ambulance before you start ?
Stewie