troubleshooting conflict

NJallDAY

macrumors newbie
Original poster
Jun 10, 2014
3
0
Hello everyone, new to the forums and just need a few pointers. I have a 20" imac A1076 power PC, and a couple years ago I came home from a weekend away and my iMac was off and unresponsive. I brought it to a local computer repair shop and they told me the power supply was bad. After parts and labor they wanted close to $700 to do the work. I said no and purchased a laptop and stowed my iMac in my closet until a few days ago.

I opened up the case to remove the power supply still under the impression that was the issue. I followed a troubleshooting guide on apple support and its leading me to the logic board being the problem. The article was archived so I don't know how relevant it is, so please correct me if I'm wrong.

Power button on back panel does not start machine
The diagnostic LED 1 is illuminated indicating power supply is live
Internal power button does not start machine
Reset SMU, tried internal power button again, machine does not start
Pressed internal power button again, LED 2 does not illuminate at all indicating logic board needs to be replaced.

Bellow is the link to the guide I used, if anyone can take a quick look and let me know if I'm correct in my diagnosis I would really appreciate it. Thank you
http://support.apple.com/kb/ht2173
 

rkaufmann87

macrumors 68000
Dec 17, 2009
1,760
38
Folsom, CA
Hello everyone, new to the forums and just need a few pointers. I have a 20" imac A1076 power PC, and a couple years ago I came home from a weekend away and my iMac was off and unresponsive. I brought it to a local computer repair shop and they told me the power supply was bad. After parts and labor they wanted close to $700 to do the work. I said no and purchased a laptop and stowed my iMac in my closet until a few days ago.

I opened up the case to remove the power supply still under the impression that was the issue. I followed a troubleshooting guide on apple support and its leading me to the logic board being the problem. The article was archived so I don't know how relevant it is, so please correct me if I'm wrong.

Power button on back panel does not start machine
The diagnostic LED 1 is illuminated indicating power supply is live
Internal power button does not start machine
Reset SMU, tried internal power button again, machine does not start
Pressed internal power button again, LED 2 does not illuminate at all indicating logic board needs to be replaced.

Bellow is the link to the guide I used, if anyone can take a quick look and let me know if I'm correct in my diagnosis I would really appreciate it. Thank you
http://support.apple.com/kb/ht2173
With due respect you will be spending money on a near 10 year old machine, why not consider getting a replacement Mac? In many countries Apple sells refurbished Macs on their website, these machines are near current or current models, save hundreds of $, come with the same warranty as a new machine, are eligible for AppleCare are virtually identical to a new machine. In short there is no down side. Why spend hundreds on a 10 year old machine when the same investment can get you closer to a new(er) machine that will far out-perform your old machine?
 

NJallDAY

macrumors newbie
Original poster
Jun 10, 2014
3
0
I bought the machine for $250 second hand in 2007, and I found a replacement logic board for $70 shipped so my investment is still minimal. I was hoping it was the power supply, capacitors are usually the component that fails the most and replacements are cheap. This is more of a project, I plan to install a custom Linux kernel for running building automation and configure field devices so even if I need to replace the board the $70 is worth it for me. If it were my personal machine I would consider a more current model, but thanks for the suggestion.

EDIT: i ran through that guide again and when pressing the internal power button i here a very faint click from the power supply, like a contact releasing. I think im going to replace the capacitors in the power supply before i go messing with the logic board. The shop i had brought it to in the first place, although very expensive, are competent technicians. They may have used a bench tester or another power supply to come to their conclusion.
 
Last edited:

NJallDAY

macrumors newbie
Original poster
Jun 10, 2014
3
0
Confident some caps went bad in the PS found a simple guide detailing what kind of voltage you should see from any pin to ground. Went through them with my multi-meter and most of them are dead. Time to order a cap replacement kit
 
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