Apple G5 all-in-one computer - UK Vintage Radio Repair and Restoration Discussion Forum

bill knox · 18th Jan 2022, 12:46 pm

Hi

I have been given one of these to have a look at, I must confess that I have never been inside one of these before.

what it does is, on turning on, it all works OK but after approx. 5-10 it turns itself off, on looking inside both fans are working OK.

My instincts are that it is either power supply or the CPU overheating but I am hoping that some one here will know more.

I will post a picture in the next few minutes

Regards

Bill

bill knox · 18th Jan 2022, 12:50 pm

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Picture as promised

Regards

Bill

paulsherwin · 18th Jan 2022, 1:16 pm

I don't have much experience with these, but the symptoms do sound like the processor going overtemp and shutting down. Check all the heatsinks are in place and haven't been dislodged in transit, and that the airflow channels are all clear.

I think you can monitor the processor core temp while the system is still working, but I can't remember how you do it. I only have a superficial acquaintance with MacOS.

Nuvistor · 18th Jan 2022, 1:55 pm

If you have the original disk 1 install DVD there may be a hardware test on it. The later Intel models that came with Leopard OS X 10.5 had one.
It’s a long time since I installed these iMac G5 models (2004?) so I can’t confirm if the AHT was supplied but worth a look if the DVD is available.

Radio Wrangler · 18th Jan 2022, 5:23 pm

An iMac with the G5 PowerPC processor (made by IBM)

They have a secondary microprocessor, tasked with sequencing boot-up and looking after fan speeds and core temperatures.

The G5 was a fast processor in its day, but it achieved this by burning up power. There are temperature sensors scattered across its die and the ancillary CPU reads them.

I ran one of these for 8 years until it would boot up and run OK but its fans (all of them according to diagnostics widget) would run absolutely flat out. It was very very loud. The fault traced back to a sensor on the CPU chip. Irreprarable by proper means, but might have been bodge-able.

It was time to retire the machine. It always ran very hot, as G5s were known to.

S the first step with bootup or thermal control problems is to investigate the ancillary CPU, the housekeeping one.

This isn't an intel CPU, and Mac OSX left it behind around about the leopard or snow leopard era. I don't know if I have installation discs still. I'll keep an eye open.

David

bill knox · 18th Jan 2022, 6:18 pm

Hi

Things have moved on slightly since this morning, the customer has now given me the G5

I did think that it was CPU or PSU overheating

Unfortunately, the customer does not have any disks and I don't either so if someone has a disk or disks that they can copy, if that is possible I would be very grateful.

any further comments gratefully received

Bill

Lloyd 1985 · 18th Jan 2022, 6:34 pm

I’ve got one of these, it was sold as faulty because of power issues, on opening it was noted that many of the electrolytic capacitors on the logic board were bulging and leaking, they were all Rubycon branded, I replaced the lot and it’s been working ever since! I did have some re-install discs somewhere, if I come across them I’ll see if I can make a copy.

Regards
Lloyd

paulsherwin · 18th Jan 2022, 6:45 pm

It would certainly be worth checking for bulging caps. They can produce all sorts of strange symptoms.

There are some versions of Linux that you can load onto these if you can sort out the fault.

https://www.pcwdld.com/best-powerpc-linux-distros

Nuvistor · 18th Jan 2022, 7:06 pm

If you get it working and keep it off the internet there were some easy to use but powerful video and photo editing software supplied with the computer.

On the other hand if you want modern internet access then Linux is probably the way forward, the old OSX OS will not fair well with security and performance issues.

bill knox · 20th Jan 2022, 1:32 pm

After a long struggle I have managed to remove the logic board, looking at the capacitors I cannot see any that are leaking or bulging, there are a multitude of 1800uf and 1000uf plus a lot of others.

These capacitors I presume are the ones that need to be changed, the original ones are made by NICHICON, what about the others there are a lot of various values??

There is a lead that I cannot find where it goes to, there are 2 connectors that are similar but I can only find 1 small board with a suitable receptacle, one lead is slightly shorter than the other.

I think that the logic board has been out before as the heat transfer compound on the CPU is thick and crusty and the board separated too easily from the heat board, that may even be the original problem.

There is a large heatsink with screws that do not have any slot or any means of undoing them, are there electrolytics underneath it that normally require changing

?

Any chance someone will know where is goes

Regards

Bill

paulsherwin · 20th Jan 2022, 3:02 pm

I don't think you'll be able to pursue the caps issue if none of them are visibly sick. You'd need to remove and test every one - possible, but a huge job.

The heatsinking issues sound much more worth pursuing. From other reports on the web, it sounds as if the temperature management on these is pretty borderline even in the absence of a fault.

18th Jan 2022, 12:46 pm	#1
bill knox Hexode Join Date: Mar 2011 Location: Wilstead, Bedfordshire, UK. Posts: 367	Apple G5 all-in-one computer Hi I have been given one of these to have a look at, I must confess that I have never been inside one of these before. what it does is, on turning on, it all works OK but after approx. 5-10 it turns itself off, on looking inside both fans are working OK. My instincts are that it is either power supply or the CPU overheating but I am hoping that some one here will know more. I will post a picture in the next few minutes Regards Bill

18th Jan 2022, 12:50 pm	#2
bill knox Hexode Join Date: Mar 2011 Location: Wilstead, Bedfordshire, UK. Posts: 367	Re: Apple G5 all-in-one computer Picture as promised Regards Bill

18th Jan 2022, 1:16 pm	#3
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,934	Re: Apple G5 all-in-one computer I don't have much experience with these, but the symptoms do sound like the processor going overtemp and shutting down. Check all the heatsinks are in place and haven't been dislodged in transit, and that the airflow channels are all clear. I think you can monitor the processor core temp while the system is still working, but I can't remember how you do it. I only have a superficial acquaintance with MacOS.

18th Jan 2022, 1:55 pm	#4
Nuvistor Dekatron Join Date: Aug 2013 Location: Wigan, Greater Manchester, UK. Posts: 9,431	Re: Apple G5 all-in-one computer If you have the original disk 1 install DVD there may be a hardware test on it. The later Intel models that came with Leopard OS X 10.5 had one. It’s a long time since I installed these iMac G5 models (2004?) so I can’t confirm if the AHT was supplied but worth a look if the DVD is available. __________________ Frank

18th Jan 2022, 5:23 pm	#5
Radio Wrangler Moderator Join Date: Mar 2012 Location: Fife, Scotland, UK. Posts: 22,858	Re: Apple G5 all-in-one computer An iMac with the G5 PowerPC processor (made by IBM) They have a secondary microprocessor, tasked with sequencing boot-up and looking after fan speeds and core temperatures. The G5 was a fast processor in its day, but it achieved this by burning up power. There are temperature sensors scattered across its die and the ancillary CPU reads them. I ran one of these for 8 years until it would boot up and run OK but its fans (all of them according to diagnostics widget) would run absolutely flat out. It was very very loud. The fault traced back to a sensor on the CPU chip. Irreprarable by proper means, but might have been bodge-able. It was time to retire the machine. It always ran very hot, as G5s were known to. S the first step with bootup or thermal control problems is to investigate the ancillary CPU, the housekeeping one. This isn't an intel CPU, and Mac OSX left it behind around about the leopard or snow leopard era. I don't know if I have installation discs still. I'll keep an eye open. David __________________ Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done

18th Jan 2022, 6:18 pm	#6
bill knox Hexode Join Date: Mar 2011 Location: Wilstead, Bedfordshire, UK. Posts: 367	Re: Apple G5 all-in-one computer Hi Things have moved on slightly since this morning, the customer has now given me the G5 I did think that it was CPU or PSU overheating Unfortunately, the customer does not have any disks and I don't either so if someone has a disk or disks that they can copy, if that is possible I would be very grateful. any further comments gratefully received Bill

18th Jan 2022, 6:34 pm	#7
Lloyd 1985 Nonode Join Date: Jun 2008 Location: Coningsby, Lincolnshire, UK. Posts: 2,818	Re: Apple G5 all-in-one computer I’ve got one of these, it was sold as faulty because of power issues, on opening it was noted that many of the electrolytic capacitors on the logic board were bulging and leaking, they were all Rubycon branded, I replaced the lot and it’s been working ever since! I did have some re-install discs somewhere, if I come across them I’ll see if I can make a copy. Regards Lloyd

18th Jan 2022, 6:45 pm	#8
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,934	Re: Apple G5 all-in-one computer It would certainly be worth checking for bulging caps. They can produce all sorts of strange symptoms. There are some versions of Linux that you can load onto these if you can sort out the fault. https://www.pcwdld.com/best-powerpc-linux-distros

18th Jan 2022, 7:06 pm	#9
Nuvistor Dekatron Join Date: Aug 2013 Location: Wigan, Greater Manchester, UK. Posts: 9,431	Re: Apple G5 all-in-one computer If you get it working and keep it off the internet there were some easy to use but powerful video and photo editing software supplied with the computer. On the other hand if you want modern internet access then Linux is probably the way forward, the old OSX OS will not fair well with security and performance issues. __________________ Frank

20th Jan 2022, 1:32 pm	#10
bill knox Hexode Join Date: Mar 2011 Location: Wilstead, Bedfordshire, UK. Posts: 367	Re: Apple G5 all-in-one computer After a long struggle I have managed to remove the logic board, looking at the capacitors I cannot see any that are leaking or bulging, there are a multitude of 1800uf and 1000uf plus a lot of others. These capacitors I presume are the ones that need to be changed, the original ones are made by NICHICON, what about the others there are a lot of various values?? There is a lead that I cannot find where it goes to, there are 2 connectors that are similar but I can only find 1 small board with a suitable receptacle, one lead is slightly shorter than the other. I think that the logic board has been out before as the heat transfer compound on the CPU is thick and crusty and the board separated too easily from the heat board, that may even be the original problem. There is a large heatsink with screws that do not have any slot or any means of undoing them, are there electrolytics underneath it that normally require changing? Any chance someone will know where is goes Regards Bill Last edited by bill knox; 20th Jan 2022 at 1:43 pm.

20th Jan 2022, 3:02 pm	#11
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,934	Re: Apple G5 all-in-one computer I don't think you'll be able to pursue the caps issue if none of them are visibly sick. You'd need to remove and test every one - possible, but a huge job. The heatsinking issues sound much more worth pursuing. From other reports on the web, it sounds as if the temperature management on these is pretty borderline even in the absence of a fault.