PowerMac G5 not turning on

[error2507]

Hey! So I recently got a PowerMac G5 and when I first booted it, just the fans where spinning but nothing else. I thought I could solve that problem later and decided to clean the Mac up, since there was dust everywhere. After I did that, I wanted to turn it on again. But nothing happened. When I press the power button the small light lights up but as soon as I release it the light is off.
Things that "went wrong" while disassembling my Mac:
- I didn't install all screws at the processor, because there is a very deep hole between the two processors.
- The screw of the graphics card fell all the way down under the power supply which I didn't clean up because I was afraid of an electric shock. But I turned the Mac and it felt out so I could use it again.

(Sorry for my English)

 

[1042686]

PSU power - When you plug the power cord into the psu at the back of the PMG5 case, do you hear a "click"? If there is no "click" sound, then the PSU has most likely failed and would need to be replaced. That is how the PSU death of my Dual CPU 2Ghz PMG5 presented itself.

No boot/CPU hardware - It is certainly best practice to get the proper screw drivers to correctly reinstall all of the CPU heatsink hardware - they are there for a reason (by design) and are not optional. This could certainly cause problems with CPU temperature and premature shutdown if the heatsink is not seated properly causing the cpu to over heat.

GPU screw - In regards to the GPU "screw", I assume this is the screw that attaches the card to the case. Definitely try and find another screw that will fit or go fishing for the screw you lost in your case. Either way, until you retrieve it, I've used a wood toothpick stuck through the hole (small zip ties too) to help support/stabilize various cards until I sourced replacement screws.

Ramped up fans - When a PMG5 cpus are taken apart and reassembled for cleaning, repasting, replacement etc. often its fans will need to be recalibrated using the Apple Service Disk. Until then, you'll get full blast jet engine fans ramping up at boot. I dont recall which version you need for your PMG5 but folks here know and can chime in.

Generally speaking, when you take the computer apart, double check that all of your power cabling is correctly and firmly reattached. Ifixit as well as youtube have step by step how-to tutorials on how to disassemble & reassemble PMG5s (and the tools you'll need for the job).

Best of luck to you!

 

[error2507]

Thanks for your answer!

PSU power - When you plug the power cord into the psu at the back of the PMG5 case, do you hear a "click"? If there is no "click" sound, then the PSU has most likely failed and would need to be replaced. That is how the PSU death of my Dual CPU 2Ghz PMG5 presented itself.

I just tried it and there is a click.

No boot/CPU hardware - It is certainly best practice to get the proper screw drivers to correctly reinstall all of the CPU heatsink hardware - they are there for a reason (by design) and are not optional. This could certainly cause problems with CPU temperature and premature shutdown if the heatsink is not seated properly causing the cpu to over heat.

I installed all screws except for 4. Two of them look strange, the screw threads are small but the "head" is pretty long.

GPU screw - In regards to the GPU "screw", I assume this is the screw that attaches the card to the case. Definitely try and find another screw that will fit or go fishing for the screw you lost in your case. Either way, until you retrieve it, I've used a wood toothpick stuck through the hole (small zip ties too) to help support/stabilize various cards until I sourced replacement screws.

I already found it and got it out of the case. So this isn't the problem ):

Ramped up fans - When a PMG5 cpus are taken apart and reassembled for cleaning, repasting, replacement etc. often its fans will need to be recalibrated using the Apple Service Disk. Until then, you'll get full blast jet engine fans ramping up at boot. I dont recall which version you need for your PMG5 but folks here know and can chime in.

The fans don't spin at all.


Basically nothing happens.

 

[1042686]

From here on out, I would look at a service manual for trouble shooting your machine. Below is the doc I've successfully used.

http://tim.id.au/laptops/apple/powermac/powermac_g5.pdf

I dont know what model G5 you have however the linked doc spans many models over several years of PMG5 production. I've used this doc to diagnose and service my aging dual 2.0ghz the few times it suffered from component failure (ram, PSU etc.).

Either way, making sure all of your PSU cabling is correctly attached to the lobo and that your CPU/s are attached to your heatsinks correctly and that the heatsinks are correctly mounted onto your lobo are obvious starting points as well.

Since you'll most likely be pulling these back out to get them in correctly, I also recommend cleaning and repasting your cpu to the heat sink.

Once you fix your PM, you'll probably need to recalibrate the fans, so a copy of ASD is needed for the recalibration process or you'll have fans running at mach10 all the time.

Best of luck to you.

 

[pl1984]

Ramped up fans - When a PMG5 cpus are taken apart and reassembled for cleaning, repasting, replacement etc. often its fans will need to be recalibrated using the Apple Service Disk. Until then, you'll get full blast jet engine fans ramping up at boot. I dont recall which version you need for your PMG5 but folks here know and can chime in.

How is the system aware you've done this and why would the fans run faster if the repasting should be lowering the temperature? Isn't there a thermal sensor which informs the system what the temperature of the CPU is?

 

[AphoticD]

Thanks for your answer!

I just tried it and there is a click.


I installed all screws except for 4. Two of them look strange, the screw threads are small but the "head" is pretty long.


I already found it and got it out of the case. So this isn't the problem ):


The fans don't spin at all.


Basically nothing happens.

Which model G5 do you have?

On the PowerMac11,2 Dual Core and Quad models (Late 2005), the CPU mounting screws also perform the function of clicking the CPU card’s connector into the slot on the logic board - no amount of pushing it down will cause it to click into place, it must be fully screwed down.

The earlier 7,2 models can be pushed down into the slot manually and then screwed down to secure. I’m not sure about the 7,3 model though.

I would also recommend you get the right tool for the job and try reseating the CPU(s) again.

 

[1042686]

I dont really know, PL1984.

When I disassembled my DC2.0 PMG5 to replace the dead psu (also pulled the CPUs to repaste & deep clean since it was apart) when I got it all back together the fans went on overdrive. My laymen understanding was that when you pull the CPUs/mobo (for whatever task) that this often messes with the fan calibration causing fans ramping up as I experienced. I certainly could be wrong however.

Anyhoo, so my assumption driving my response was that when I pulled the componentry apart, that act (pulling CPUs from the lobo to clean & repaste) reset the cooling/temperature systems & op might experience this as he/she was getting spinning fans initially before messing with it & could again & would want to know how to reel them back in.

Anyhow, To fix it I used the ASD tools.

http://www.dreamsupport.us/download..._Disks_25_GB/ASD v 2.5.8 Dual Boot CD (2005)/

Best of luck to you.

 

[AphoticD]

I dont really know, PL1984.

When I disassembled my DC2.0 PMG5 to replace the dead psu (also pulled the CPUs to repaste & deep clean since it was apart) when I got it back together the fans went nuts. Fsw

So my assumption was that when I pulled the componentry apart, that act reset the cooling/temperature systems.

To fix it I used the ASD tools.

http://www.dreamsupport.us/downloads/apple-mac/Apple_Service_Diagnostic_Disks_25_GB/ASD v 2.5.8 Dual Boot CD (2005)/

Is the later ASD 2.6.3 version required for the Dual Core and Quad models?

I hadn’t considered what goes on when changing thermal paste, but the several times I have done this, recalibration wasn’t required.

When I upgraded my DC 2.0 with a DC 2.3 card I went though calibration again, but it was allowed because of the change of CPU card.

When I have attempted to calibrate in ASD at other times, it has reported back that calibration wasn’t needed and that was that.

On the earlier models (and probably the Quad) you can force a recalibration by swapping the CPU cards around and then booting into ASD.

 

[1042686]

No idea Dan although the linked 2.6.3 ASD description states late 2005 powermacs, which the quad is.

https://archive.org/details/asd.2.6.3

 

[error2507]

Which model G5 do you have?

On the PowerMac11,2 Dual Core and Quad models (Late 2005), the CPU mounting screws also perform the function of clicking the CPU card’s connector into the slot on the logic board - no amount of pushing it down will cause it to click into place, it must be fully screwed down.

The earlier 7,2 models can be pushed down into the slot manually and then screwed down to secure. I’m not sure about the 7,3 model though.

I would also recommend you get the right tool for the job and try reseating the CPU(s) again.

How can I see which model I have?

 

[AphoticD]

How can I see which model I have?

Open the side aluminum door and then look at the decal on the panel below the clear “air deflector” door - there will be specs, model, serial, barcodes, etc

 

[error2507]

My serial number is CK422H6MR5J . I looked it up on everymac.com and it says A1047 (EMC 1969) is my model name. So do I need the screws? I pretty much don't know anything about Mac dissasemblying but I think the power button is failing the job but as I said I don't know.

 

[AphoticD]

My serial number is CK422H6MR5J . I looked it up on everymac.com and it says A1047 (EMC 1969) is my model name. So do I need the screws? I pretty much don't know anything about Mac dissasemblying but I think the power button is failing the job but as I said I don't know.

Given the weight of the heatsink I would say yes, you will still want to screw it down fully.

However, before you continue, take the CPUs out again and check the connectors to see if there are any bent pins, once all clear, reseat them both and try powering on.

It is also worth trying to either rotate or isolate the CPUs, try the bottom unit in the top slot and vice versa to see if you get a boot chime.

 

[error2507]

Given the weight of the heatsink I would say yes, you will still want to screw it down fully.

However, before you continue, take the CPUs out again and check the connectors to see if there are any bent pins, once all clear, reseat them both and try powering on.

It is also worth trying to either rotate or isolate the CPUs, try the bottom unit in the top slot and vice versa to see if you get a boot chime.

Can I try it with only one at a time?

 

[1042686]

Can I try it with only one at a time?

Yeah, you can try one cpu at a time in the top slot. Connect it correctly & then see if the Powermac will post. This will verify one way or the other if both CPUs are good.

 

[error2507]

Yeah, you can try one cpu at a time in the top slot. Connect it correctly & then see if the Powermac will post. This will verify one way or the other if both CPUs are good.

Okay nice. But the problem is, I don't know where to put which screw :C. Do you have a picture for me?

 

[1042686]

Okay nice. But the problem is, I don't know where to put which screw :C. Do you have a picture for me?

Ifixit.com & YouTube are good sources for step by step instructions of various Powermac G5 builds.

 

[kencu]

The only way I have ever fixed the issue you mentioned in the first post (push power button, power button lights up, click heard (in my case), fans spin for a second, then power button dims when you let it go) is to replace the power supply.

It's not terribly hard -- it takes an hour or so. It's the most common PowerPC Mac problem I've come across. I'm worried that these might one day be hard to come by. I have a couple in backup. I recall a post online where someone had converted a modern ATX power supply to work in a G5...but can't find that post just now.

Sometimes when you remove the processor units, the thermal calibration information is reset. The fans then run at 100% by default to save your system. As above, you have to rerun the thermal calibration -- it takes not long to do that, 15 minutes or so I recall, once you have found the right image and made a bootable CD.

 

[error2507]

The only way I have ever fixed the issue you mentioned in the first post (push power button, power button lights up, click heard (in my case), fans spin for a second, then power button dims when you let it go) is to replace the power supply.

It's not terribly hard -- it takes an hour or so. It's the most common PowerPC Mac problem I've come across. I'm worried that these might one day be hard to come by. I have a couple in backup. I recall a post online where someone had converted a modern ATX power supply to work in a G5...but can't find that post just now.

Sometimes when you remove the processor units, the thermal calibration information is reset. The fans then run at 100% by default to save your system. As above, you have to rerun the thermal calibration -- it takes not long to do that, 15 minutes or so I recall, once you have found the right image and made a bootable CD.

Thanks but in my case not even the fans spin.

 

[error2507]

From here on out, I would look at a service manual for trouble shooting your machine. Below is the doc I've successfully used.

http://tim.id.au/laptops/apple/powermac/powermac_g5.pdf

I dont know what model G5 you have however the linked doc spans many models over several years of PMG5 production. I've used this doc to diagnose and service my aging dual 2.0ghz the few times it suffered from component failure (ram, PSU etc.).

Either way, making sure all of your PSU cabling is correctly attached to the lobo and that your CPU/s are attached to your heatsinks correctly and that the heatsinks are correctly mounted onto your lobo are obvious starting points as well.

Since you'll most likely be pulling these back out to get them in correctly, I also recommend cleaning and repasting your cpu to the heat sink.

Once you fix your PM, you'll probably need to recalibrate the fans, so a copy of ASD is needed for the recalibration process or you'll have fans running at mach10 all the time.

Best of luck to you.

So I tried putting all screws where they should be but it is still not working. D: I tried only one CPU in the top slot.

 

[error2507]

Yeah, you can try one cpu at a time in the top slot. Connect it correctly & then see if the Powermac will post. This will verify one way or the other if both CPUs are good.

I tried both but still nothing.....