crwdns2936637:0crwdne2936637:0 crwdns2853008:0crwdne2853008:0 crwdns2861143:0crwdne2861143:0

Model A1312 / Mid 2010 / 3.2 GHz Core i3 or 2.8 & 3.6 GHz Core i5 or 2.93 GHz Core i7, ID iMac11,3

crwdns2934591:0383crwdne2934591:0 crwdns2934593:0crwdne2934593:0

crwdns2933897:0crwdne2933897:0

Diagnostic LED 1 blinks once

so i’ve recently been given a Mid 2010 27” iMac that wasn’t powering on. Initially i thought i must most probably be the Power supply that had croaked it and needed to be replaced because when i plug in the power the diagnostic LED 1 flashes once then once again but not as bright that second time, as if it was loosing power. No other LEDs are lit.

I have replaced the PSU with a known working unit but still getting the same thing.

im hoping its not the logic board that has an issue or a short on it,

is there any chance it would be the jack/EMI unit where the power goes into the imac?

crwdns2934089:0crwdne2934089:0 crwdns2934093:0crwdne2934093:0

crwdns2934109:0crwdne2934109:0

crwdns2853045:0crwdne2853045:0 crwdns2853046:0crwdne2853046:0
crwdns2889612:0crwdne2889612:0 0
crwdns2934285:0crwdne2934285:0

crwdns2933313:01crwdne2933313:0

crwdns2934221:0crwdne2934221:0
crwdns2931211:0crwdne2931211:0 crwdns2931215:0crwdne2931215:0 crwdns2934225:0crwdne2934225:0

crwdns2933897:0crwdne2933897:0

You have a short within the logic board and/or the MXM video board.

My money is on the video board! Do you have the correct one to test things?

Otherwise its following the power rails with a DVM and a set of schematics and boardview drawings.

crwdns2934105:0crwdne2934105:0

crwdns2853045:0crwdne2853045:0 crwdns2853046:0crwdne2853046:0
crwdns2889612:0crwdne2889612:0 0

crwdns2944067:02crwdne2944067:0:

Thanks! But darn was really hoping for the video board being the issue. Removed it but am still getting the same problem.

Must be a short on the logic board then.

crwdns2934271:0crwdnd2934271:0crwdne2934271:0

@ahkoo - Follow the yellow brick road ;-}

Get a DVM and a set of schematics and boardview drawings following the power rails and check the caps.

You might want to find someone with the deeper skills to help you.

crwdns2934271:0crwdnd2934271:0crwdne2934271:0

crwdns2934285:0crwdne2934285:0

crwdns2934229:0crwdne2934229:0

Ahkoo crwdns2934231:0crwdne2934231:0
crwdns2936625:0crwdne2936625:0:

crwdns2936751:024crwdne2936751:0 4

crwdns2936753:07crwdne2936753:0 7

crwdns2936753:030crwdne2936753:0 22

crwdns2942667:0crwdne2942667:0 191