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Model A1419 / Late 2013 / 3.2 & 3.4 GHz Core i5 or 3.5 GHz Core i7 Processor, ID iMac14,2

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Has my PSU blown my logic board

Same old initial problem, black screen and no response, however I have no diagnostic LEDs.

General consensus was to replace the PSU and power cable. After doing this I still have no diagnostic LEDs. (I have since returned the newly order PSU) The logic board would be a logical place to move to next. And that brings me here.

Is it possible that the PSU has blown the logic board in some way but still show voltage passing through the power cable, PSU and logic board?

And if so, upon replacing the logic board, is it possible the old PSU could blow that too?

Both old and new PSUs had a very quiet slight electrical hum and this is the only sound the Mac makes when the power cable is plugged in.

The model I’m using is the iMac 27" A1419 Late 2015 5K i5 3.3 GHz.

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It is very possible that the PSU caused a power surge unfortunately

When power supply’s fail they can take lots of things down with them like the logic board and screen…

If you can take the logic board out and look for any burn marks or discolouration ,that will help indicate if the logic board will need replaced or repaired

Here’s the guide for getting it out

Sostituzione scheda logica iMac Intel 27" Display Retina 5K

If you are unsure of any things you can use this guide to upload some photos so we can help you with it

Aggiungere immagini ad una domanda

Hopefully this helps

Any questions please ask


Immagine iFixit


Aggiungere immagini ad una domanda


Molto facile

2 - 5 minutes

Immagine iMac Intel 27" Retina 5K Display Scheda logica


Sostituzione scheda logica iMac Intel 27" Display Retina 5K



2 hours

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That’s useful to know. If the logic board was shot it would make sense that the new PSU didn’t turn on LED1. It seems to be about the only reason it wouldn’t work (bar power source problems)


Following your prompt reply I decided to further inspect the PSU. With a visual inspection I couldn’t spot anything significant and with the power on I was trying to isolate the hum.

Whilst doing this a knocked screw has managed to fall and find into the PSU, connecting something to something which then proceeded to go off like a flash bang.

So that answers that one I guess aha

I was going to source a replacement logic board tomorrow but now with the PSU as well. I think a refurbished/used Mac and a hard drive swap is the way forward.

Apologies it’s a bit of a dead end but thanks for answering my question either way


@ramba123 - Sadly, your power service might have been the source of the event. Make sure to get a good surge suppressor or better yet a good UPS as well as check your buildings outlet wiring as well as the breaker panels ground connection. That way your gear is protected from something coming from the power lines and for lighting strikes.

Basically, the surge came into your system killing your power supply and logic board.



Sound like a plan

Please let me know if there is anything else



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Zach Ramba sarà eternamente grato.
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