iMac G5.. thats really noisy.

[wardsenatorfe92]

I'm seeking input on the cure to fix one of the other Macs in our classroom. It's a iMac G5.. not entirely sure of the specifications. It's a video editing computer but has remained unhooked due to some problem thats been plaguing it (like all the other Macs in our department).

Anywho, once Mac OS X has loaded the desktop, the fans go into "jet speed". I've messed around with it, putting it to sleep, logging out and logging in. The fans only roar when the machine is fully logged in.. making me think its some sort of task. When its at the login window when its first booting up, it doesn't make noise.. and usually doesn't make noise the first few minutes its turned on.. then it starts "roaring". I've opened Activity Monitor and didn't see anything using high CPU or whatnot.. so I'm not entirely sure how to pinpoint the problem. If it helps, I'm quite sure that its running Tiger (10.4).

Advice will be greatly appreciated!

Thanks,

Jake

 

[Floydy]

The iMac G5...

What size is the display, does it have a built in camera above the display?

Bear in mind that a hosed software update OR certain versions of Mac OS may play havoc with the System Management Unit

All software updates should be carried out or re-run from a good installer if one had previously been carried out.

Check to see what is set to run at startup in the login items section of user accounts

A 'pre' iSight iMac G5 is relatively simple to get into for inspection of dust or location of fan noise

The following assumes it is the most common iMac G5 (17" ALS):

The grill on the bottom of the iMac G5 lets a trio of fans draw cool air into the system. Thermal software spins the fans fast or slow as needed, passing the heated air through a slit on the back cover. As the system usage increases, the fans will adjust their speed to meet the cooling needs of the system. Accumulating dust can obstruct the flow of air through the system causing the fans to run faster than normal. In severe cases the system may overheat and unexpectedly shut down.

Remove all dust using propellant or a 'static-safe' vacuum cleaner

If possible, reset the SMU:

• Unplug all cables from the computer, including the power cord.

• Wait 10 seconds.

• Plug in the power cord while simultaneously pressing and holding the power button on the back of the computer.

• Let go of the power button.

• Press the power button once more to start up your iMac G5.

Reset PRAM (Parameter RAM):

• If your iMac is on, turn it off by pressing the power button in until the computer powers off.

• You should hear the drives and fans go quiet.

• Wait for a few seconds.

• While the computer is off, with your left hand, hold down the Apple key, the option key next to it, and the letter R.

• When you have them all pressed push the power button with your right hand and then quickly move that hand to hold down the letter P.

• Keep the four keys pressed while the computer starts up.

• Make sure you hold down the four keys (P-R-Command-Option) while the computer starts up.

• When you keep all the keys held down, you will hear the startup chime over and over again (about every ten seconds) until you let go.

• After you hear the second chime, you can let go of the keys.

• If you didn't hear at least two startup chimes, go to step one and try again.

• It's important that you two startup chimes when performing this procedure. This indicates that you have successfully reset the computer's PRAM (Parameter RAM).

 

[Mars478]

Welcome to the club....

 

[wardsenatorfe92]

Okay, well I got to work on it today.. somewhat. It's a first generation iMac G5.. i think the specs were 1.6 GHz/ 256 MB RAM/ 80 GB, 17" screen. I reset the SMU, PRAM, NVRAM, and such.. no luck at all. I have no idea how to open the case, however I don't believe dust is a factor due to the machine shows no obvious signs of dust problems. (I could be wrong, but we have other Macs in the room that i'm sure are full of dust and they still work without problem.. even though thats not a good thing lol).

I've researched a little bit, and I think its the logic board. The machine, while I tried to update the system software (it's at version 10.4.6), it would not stay on long enough to update. I was unaware of this symptom. The machine would simply go into sleep mode, no moon light.. and I'd have to keep clicking the mouse to get it to wake up. Also, after I reset the SMU and such, the fan problems now start on startup, making me thing the issue is now with the machine itself.

Repairs, eh.. not in my department. I don't own the machine, and I'm not qualified to be physically repairing it.. just trying to get it in working state so that they don't have to send it out for repairs.

Thanks guys!

 

[Floydy]

I've researched a little bit, and I think its the logic board. The machine, while I tried to update the system software (it's at version 10.4.6), it would not stay on long enough to update. I was unaware of this symptom. The machine would simply go into sleep mode, no moon light.. and I'd have to keep clicking the mouse to get it to wake up. Also, after I reset the SMU and such, the fan problems now start on startup, making me thing the issue is now with the machine itself.

Oh dear

Some early iMac G5's suffer with one of three issues - swollen/leaking capacitors on the MLB, a defective power supply OR both issues

The power supply is cheap and easy to replace but the MLB - Well forget it, just not worth the hassle and expense of replacement or repair.

Apple did have a repair extension program in place for these issues but that was for units that were within 3 years of the purchase date and certainly less than the 5 years that this iMac is.

The REP for iMac G5 is no longer on the Apple website so that is not an option any longer.

That model iMac G5 is really easy to get into - You need a large phillips screw driver to undo the crosshead screws on the underside of the enclosure (perforated). Lay the unit display side down and loosen the screws which do not come out completely. Lift the back off starting from the bottom and swivel the rear cover up and away.

On the MLB, there are clusters of capacitors near the bottom and next to the CPU ducting. If any of these capacitors are 'domed' or have the appearance of a pyramid at the top, then the MLB is shot. Symptoms will be random hard shutdowns, failure to power on right away, wake from sleep, issues reading the HDD, garbled video (in extreme cases) OR screwed SMU. These problems may take a while to appear and then will often be reproducible as soon as normal operating temperature is reached.

If the capacitors on the MLB are in good shape, then the power supply is either clogged with dust (a flaw of this design) or on its way out. It may benefit from a good dusting though (no need to remove). A replacement PSU is surprisingly cheap. It is easy to remove although a tight fit.

Replacement of the rear cover is a little fiddly and you need to ensure it fits flush all the way around before tightening the screws...

 

[phreakout]

Also, if you have the original install discs that came with the iMac, you can run the Apple Hardware Test. You will need to restart the iMac and hold down the Option key whilst restarting. You soon see a violet or blue background with straight and curved arrows. Look for a button/icon to pop up labeled "Apple Hardware Test", click on it and click on the straight arrow. This will boot the iMac off of the CD/DVD disc and into AHT. There will be several tests to pick from, but there should be one for the cooling fan controls. Run that along with the CPU calibration tests.

73s de Phreakout. :rambo: