Thanks for the help. I’ll check for temp issues tonight. I did blow out vents, fans and such before re-assembling.

I asked about the SMU because I had a fuzzy memory of reading a note somewhere. I re-found the note here: http://support.apple.com/kb/HT2173 the Note under step 9. If this is true, my SMU is reset upon unplug and replug of the power cord and a manual reset wouldn’t be necessary.

Jim Jackson

There are a couple of things I would look at.

One item is to make sure the computer is not overheating. I would try blowing a fan on the backside with the cover removed. If you can get it to stay on, I would install the free temperature monitor program to see what is going on with the temperature. Of course, make sure all your fans are working in the iMac itself. Sometimes there is a lower squirrel cage fan hidden at the very bottom on some of the iMac models. I have seen this fan not functioning and the iMac will overheat. Also make sure all the cooling fins are blown out. Sometimes these get clogged up and reduce the air flow.

As far as resetting the SMU and PRAM, I don’t believe the SMU is reset automatically with the ambient light sensor model. I would follow the Apple instructions for how to reset the SMU.

Jim

I received the cap kit, thanks!, for the power supply problem, installed the caps and powered up the iMac. It came up fine and then shut off after a couple minutes. I started it back up and reset the PRAM. It started up fine and ran for about 15 minutes and shut off. I started up again, reset the PRAM and it ran overnight and was still running when I left for work. Would it fix it for good if I reset the SMU? There was an ambient light sensor on the PS, does that mean it will reset the SMU automatically?

So close to success,

Jim Jackson

Thanks for the fast response and help:-)

Regards,

Kim

The powering down and powering up problem is typical of the the bad capacitor problem. I always say, you’ve got to fix what you find bad. In this case, having bulging caps on the MOB can in fact cause the problem you describe. I would definitely fix the MOB with new caps to begin with. Then, if you still have a problem, the original bad capacitors on the MOB could have caused something to go out in the PSU other than the PSU caps themselves.

Refer to my other Apple articles for more information.

Regards,

Jim

With Blogger, and the new templates, you can either adjust the font sizes from the template customize control panel area or you can edit the CSS using edit HTML from the template control panel also.

In WordPress files localized on your own hosted server, you would need to edit CHMOD Permissions (making the CSS file writable). This will allow you to edit the CSS file to the font sizes you wish.

Sometimes, you can also add auxiliary CSS files, or enter separate styles through the template areas.

Do you know how to change the font size and get it to single spacing in the layout of a blog???

Dallas

Wish they had written a more detailed testing procedure for this tester, But I really liked all the reviews on it, And not that you have clarified the operation, It will be a great tool! Have a customer with a system that just stopped booting, No post codes and beeps. So I thought it might be motherboard, then the power supply, after reading all the comments on Amazon about this tester, many had some issues with system not booting and found the power supply to be the probem. after using this tester, But not in my case which tested good. So I am replacing motherboard, Thanks for all your help Jim

Just to be sure of what happens when only the main 20 or 24 pin connector is plugged in, I verified the tester operation with on a known good power supply. Note that there are two +12 volt indicators. V1 +12 volt should indicate okay, and V2 +12 volt will be flashing and beeping indicating no voltage is present at V2, which is normal when none of the other cables are plugged in other than the main 20/24 pin cable. However, the PSU tester will indicate a proper voltage when an auxiliary cable is plugged in with a proper V2 +12 volts present on that DC voltage bus. This of course is with a good power supply unit. On a bad power supply unit, depending on what voltages are low or missing, will indicate a problem in those specific areas.

Regards,

Jim

I would be very leery of thinking the capacitors that you removed from another iMac are good. In fact, the process of removing the older capacitors, and the heat that is required to remove them from the board, could have damaged them. Not to mention that these are old capacitors, which would be highly suspect in having bad ones onboard both the 17 and 20 inch MOBs, even if the other caps are not bulging.

I would also verify your PSU voltages, regardless of if you think the PSUs are good or not.

Jim

Thanks for all instructions given on your site…

I am struggling with a small problem where maybe you know how to fix it!

I got this dead 17 inch iMac G5 (late model) and some caps where highly pregnant… yet it did start up with the fans spinning but no chime and no screen lighting up…

So I replaced them with some identical ones who where still looking OK from a different 20 inch iMac g5 (1st gen.) with a defective video card…

Anyways…

After putting it all back together but without putting most screws back in place, (just the mobo and frame connector ones) it does not startup anymore.

I tried both power supply units but the only LED lighting up is the first one… after the power cord is plugged in.

Both the internal and outer power button don’t seem to respond…

:s

Do you have any suggestions about what possible went wrong?

Thanks,

Peter

Yes, you would need to remove the main logic board in order to replace the caps. To do so, requires removing the mounting screws that hold the main logic board in place. There is no need to remove the main heat sink with the G5 logo on it. Keep that attached to the main logic board. There will also be various plugs and cables that will have to be removed in order to completely pull out the motherboard. I suggest removing the memory cards too. Also, suggest keeping track of where all the screws go.

I believe the Apple service manuals show the locations of the mounting screws, but be aware that some of the screws are different sizes. Here are the Apple service manuals for disassembly. Go to the section of the either the 17 or the 20 inch (depending on which one you have) and location the Logic Board Removal instructions.

Refer to my removal and replacement instructions above for more details on the iMac G5 repair procedures.

Regards,

Jim

I removed the rear cover and the 5 caps you showed on the board are bulged. The power supply caps are fine. My question is can I remove this board to R/R the caps from the rear? The IMAC manuals show every thing from the front. If you could let me know it would be great.

Thanks Steve

Thanks for the comment.

As far as any of the Apple products, I don’t believe Apple has ever released any schematics into the marketplace. As far as the PowerMac G5s, I have heard of many issues with the breakdown of the BGA (Ball Grid Array). In fact, some have written about the PowerMac having intermittent issues related to heat. For example, some will work only when it is cold, and others will work only when they are warm. In my estimation, there has to be some sort of connection type problem when this occurs.