iMac (Late 2013) Power Problem

[res6jya6]

Hey all!

The other day I was trying to mess with the cables in the back of my iMac (Late 2013) 21.5" 2.9Ghz i5 and dropped it straight on it's face.

It wasn't a long fall - merely the space between the monitor and the desk in which the iMac sits on - but it powered down immediately and I was unable to restart it. No fan, no beep, no boot screen...

I'm able to get the fans spinning by bypassing the SMC (pressing and holding the power button while plugging the unit in) but it still won't display anything.

I've removed the display to check the diagnostic LEDs - I have ONE LED lit (the bottom one) and no others light up when pressing "power".

I can't find anything out of place in the machine - it's got an NVMe SSD firmly seated in place, 8GB of RAM firmly seated in place, a few cables for speakers (firmly seated) the two power connectors (firm) the power button (firm) iSight (firm) display data (firm) display power (firm). I've literally disassembled this entire machine to no avail!

From what I've read online this is either a power supply problem or logic board problem? If anyone else has experienced anything similar, what was the main culprit? I don't want to replace both at the same time - rather see if it's one or the other first. But which one to check first?

 

[USB3foriMac]

If something drops, it is the heavy parts that can tear off. Keeping this logic in mind, there could be the following issues:
- The heavy coil(s) on the power supply is/are torn off the PCB. Check the connections with a magnifying glass. Post clear close-up pictures here for us to see.
- Any heavy part directly connected to a connector could be torn off. In your case, HDD/SSD, maybe others.

- Cables could be torn off, or could have come off their connector.
- Screen broken.
- CPU cooler could have ripped CPU off.

So best for you is probably to take it to someone who can test the individual parts.

 

[res6jya6]

I've verified that all cables and connections are secure - re seated the NVMe SSD and memory - since you said the coils on the power board could be damaged, I think I'll replace that before trying the logic board... I'm seeing them at no more than $30 on eBay which is far harder to swallow than the $300 logic board (gulp!) - Thank you for the reply!

 

[res6jya6]

 

[USB3foriMac]

Difficult to say. If you turn it around and show th3e full PCB, it might be more helpful to see any torn out pins. Particularly the large coil in pic 3 might be affected. The copper wire coils are mostly for filtering, and are much lighter so less chance to be ripped off.
Take another look at the connectors themselves, the part that is soldered onto the PCB. It is possible that one or several pins have come lose.
There is a thread on the 2011 power supply where I describe fault finding. Turned out to be a cold solder join. If you read through that, you can get an impression with what kind of problem you could be dealing with.

 

[res6jya6]

Replacing the power board did not seem to solve the problem. Still only one diagnostic LED lit up... leading me to believe the logic board is at fault?