prairiedogsplatr Posted November 21, 2009 CID Share Posted November 21, 2009 Is it possible to test a mac G5 power supply with a power supply tester. I am not very sure on how macs work at all. The mac will not turn on and shows no form of life. All caps on motherboard are looking to be good. Any advice would be appreciated. Quote Link to comment Share on other sites More sharing options...
mudmanc4 Posted November 22, 2009 CID Share Posted November 22, 2009 I would take my multimeter to the power molex. I dunno about any specific tester myself. Is this something that just happened, or you acquired the thing, or what, just looking for a bit of background to go by. Quote Link to comment Share on other sites More sharing options...
prairiedogsplatr Posted November 22, 2009 Author CID Share Posted November 22, 2009 Was my parents imac. One day they went to power on and nothing happened. Its a 22 pin psu with isight or whatever its called. The little lite censor. There is no noise coming from psu when turned on. No lights coming from anywhere on motherboard. No fans moving or hdd moving. As for molex when i hear that i think of a 4 pin molex connector. I do have a multimeter and a power supply tester for regular pc. Quote Link to comment Share on other sites More sharing options...
prairiedogsplatr Posted November 22, 2009 Author CID Share Posted November 22, 2009 I would have no idea on what prong to put the meter on. Quote Link to comment Share on other sites More sharing options...
mudmanc4 Posted November 22, 2009 CID Share Posted November 22, 2009 I would have no idea on what prong to put the meter on. Well, you could ship it to me no, I'm not kidding. I'll pay the shipping before you ship. :grin: Might be like you say, the power supply. Open the back cover(after making sure the power cord is UNPLUGGED , had to say it ) then look for the diagnostic LED's Now carefully plug the power in. Look to make sure LED 1 is ON, if it is, then it's getting power from the power supply. You may need to reset the SMU After resetting the SMU, then turn the machine on using the internal power button Does the computer power up ? If you got this far, assuming the LED#1 was lit up when you initially plugged the power cord in. If it isn't then the power supply will need to need replaced. BTW, did you use your multimeter to determine that the coed itself has continuity ? Quote Link to comment Share on other sites More sharing options...
prairiedogsplatr Posted November 23, 2009 Author CID Share Posted November 23, 2009 The lites do not lite up on motherboard. Also noted my motherboard only has 1 button that picture shows two i don't know if that makes a differance. I want to try the multimeter but have not yet due to i really do not know where to put it and do not want to fry any good parts by a shock if done in the wrong spot. Quote Link to comment Share on other sites More sharing options...
prairiedogsplatr Posted November 23, 2009 Author CID Share Posted November 23, 2009 sorry this is not the one with isight its the one with Ambient Light Sensor. Second gen emc:2055 17-inch iMac G5 (Ambient Light Sensor) Quote Link to comment Share on other sites More sharing options...
prairiedogsplatr Posted November 23, 2009 Author CID Share Posted November 23, 2009 I took out the psu and put it back in and now the led 1 will lite up. I try to push the button and even push and hold it down but machine will still not power up. Quote Link to comment Share on other sites More sharing options...
prairiedogsplatr Posted November 23, 2009 Author CID Share Posted November 23, 2009 If i hole that button down and push the 2 prongs that turn the machine on the led 1 will stay lite up and the led 2 will momentarily lite up. The machine makes a sound coming from left bottom corner (machine is face down) then it shuts off. If held down both the reset button and the power button the two fans will turn on at top. Quote Link to comment Share on other sites More sharing options...
mudmanc4 Posted November 23, 2009 CID Share Posted November 23, 2009 here is a refurbished one for that machine. It does sound like it may be the supply, from what I have read here and there, it IS a bas power supply. But I wont say that for sure, who could , you know. On the model you have , the SMU is reset when the power cord os disconnected. If the machine is worth it to you, then go get one, I know thats what I would do. It's well worth the price. Quote Link to comment Share on other sites More sharing options...
sloppy87 Posted November 23, 2009 CID Share Posted November 23, 2009 If you are getting a LED to light up that means power is getting to the board. Which means the power supply works. The power supply will either work, or not work. You still need to get a multi-meter and test the ends to see if your getting the correct voltage out of each pin-out. Sounds to me like something else is going on. Quote Link to comment Share on other sites More sharing options...
prairiedogsplatr Posted November 23, 2009 Author CID Share Posted November 23, 2009 i think i read the same place as you did mudman. this aticle here I am going to take apart the power supply and check for bad caps. Since the second led did lite up that paragraph at the very bottom says the power supply can't hold the power, and needs to be replaced. As for multi meter i would need a pin layout or directions in order to check because i really do not feel comfortable with that. These psu for mac are strange. They are made to fit by screen size some with ambient lite censor some with isight. Nothing compared to the information i would recieve when looking up a regular pc psu. The link you have provided looks like the correct psu except it does not have the acual lite censor on it and i think that could cause problems down the line i would rather not take chances. It seems that these psu are identified by a EEE code that i can't seem to find anywhere on the machine. Quote Link to comment Share on other sites More sharing options...
mudmanc4 Posted November 24, 2009 CID Share Posted November 24, 2009 If you are getting a LED to light up that means power is getting to the board. Which means the power supply works. The power supply will either work, or not work. Are you sure of this ? I'm not expert on the subject by any means, however I do know this, there are several different "sections" within power supplies, some low voltage, and some high. The higher voltages "12v" , would generally be considered the rails, because this just what they are. The lower voltages come from small step down transformers within. So any one of these components change resistance, and thats it for the connected lead. Which could cause any number of different issues. Now I'm not saying I know the supply is bad, but this is not the first time this has come up, by any means, Iv'e switched out more then a couple dozen of them personally, each with it's own distinct effects from one out of a hundred or more of the components that make up the supply, and deliver to several area's within the machine. This SHOULD be the correct pinout prariedogspltr, if it is obviously not, then you'll have to search here for it. And obviously make sure you have the corrcect one before doing anything, I don't have to say that to you, but hey Quote Link to comment Share on other sites More sharing options...
prairiedogsplatr Posted November 28, 2009 Author CID Share Posted November 28, 2009 this is what i got my info from a quote from that page Does LED 2 come on momentarily, or not at all? * Momentarily: The logic board has detected power, but the power supply cannot maintain it. Your power supply needs to be replaced. If you have an iMac G5 (Ambient Light Sensor) computer, contact your local Apple Retail Store or Apple Authorized Service Provider for service. * Not at all: Your logic board needs to be replaced. Please contact your local Apple Retail Store or Apple Authorized Service Provider for service. Sorry it has been a few days i am very sick and tryn to get the energy to think straight will get this done soon i hope as soon as i get better. Quote Link to comment Share on other sites More sharing options...
mudmanc4 Posted November 28, 2009 CID Share Posted November 28, 2009 this is what i got my info from a quote from that page Does LED 2 come on momentarily, or not at all? * Momentarily: The logic board has detected power, but the power supply cannot maintain it. Your power supply needs to be replaced. If you have an iMac G5 (Ambient Light Sensor) computer, contact your local Apple Retail Store or Apple Authorized Service Provider for service. * Not at all: Your logic board needs to be replaced. Please contact your local Apple Retail Store or Apple Authorized Service Provider for service. Sorry it has been a few days i am very sick and tryn to get the energy to think straight will get this done soon i hope as soon as i get better. Well thats what I have been finding. If you want to keep the machine, then a hundred bucks is well worth it, if not, then , well, ship it to me , and I'll replace it hahaha btw, get better fast Quote Link to comment Share on other sites More sharing options...
prairiedogsplatr Posted December 3, 2009 Author CID Share Posted December 3, 2009 Back now that i have recovered was a nasty sickness i had. I will get that power supply tested tonite via voltage meter. I am looking at it now and see a few bad caps inside the psu. Tells me that it is most deffinately the psu. I have read many places that they can be replaced for like 20$ I find no motivation to do that much work rather spend the 100$ i think. And mud only reason i am fixing this is to sell it. So if you are really that interested in it give me a shout. Quote Link to comment Share on other sites More sharing options...
mudmanc4 Posted December 3, 2009 CID Share Posted December 3, 2009 Back now that i have recovered was a nasty sickness i had. I will get that power supply tested tonite via voltage meter. I am looking at it now and see a few bad caps inside the psu. Tells me that it is most deffinately the psu. I have read many places that they can be replaced for like 20$ I find no motivation to do that much work rather spend the 100$ i think. And mud only reason i am fixing this is to sell it. So if you are really that interested in it give me a shout. Hell, dont fix it, just ship it to me :haha: Seriously get the numbers off the bad capacitors , then goto Radio Shack , I still get all my , well, most my parts n' pieces from them, have since i was a kid soldering those heathkits, amps, whatever. Quote Link to comment Share on other sites More sharing options...
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