iMac Late 2013 27" No Chime / Boot

[jasongoldworthy]

hi guys as the title says I have another 27" late 2013 imac

that was given to me with a dead hard drive ive pulled the drive.

and its not always chiming and the display don't light up.

ive looked at the diagnostic led's and only 2 come on

the bottom one to show there is 5v power and the 2nd to show its on.

it will sometimes chime but if I try to boot an installer of any sort it freezes on a black screen.

but if I leave the boot media out I get a flashing question mark folder.

any ideas if this could be a firmware issue ??

ive tried doing internet recovery and AHT but it won't run any of them.

thanks

 

[chscag]

Could be a failing power supply. Either that, or the logic board has problems. I don't think it has anything to do with the firmware. Generally the 2013 27" iMac was a good machine with few problems. I owned one and wound up giving it to my son when I upgraded. He's still using that same machine.

 

[jasongoldworthy]

Could be a failing power supply. Either that, or the logic board has problems. I don't think it has anything to do with the firmware. Generally the 2013 27" iMac was a good machine with few problems. I owned one and wound up giving it to my son when I upgraded. He's still using that same machine.

thanks for the reply.

I have another 2013 that I can try the PSU from ??

its on at the moment flashing the question mark at me.

as I said if I try to boot anything or recover from the internet it just freezes at a black screen.. with no back light or anything.

could that still be a bad PSU ?

 

[chscag]

From your original description of the problem, the PS is suspect. And of course it could still be a logic board failure.

If you have another 2013 model, you can perhaps substitute parts to isolate the problem. Sometimes trouble shooting illusive problems can be lots of work. But as a tech, you already know that.

 

[jasongoldworthy]

From your original description of the problem, the PS is suspect. And of course it could still be a logic board failure.

If you have another 2013 model, you can perhaps substitute parts to isolate the problem. Sometimes trouble shooting illusive problems can be lots of work. But as a tech, you already know that.

thanks again.

ill try the PS from my other machine and see how I go sticking back the displays isn't a big issue for me.

thanks for your time help

 

[jasongoldworthy]

From your original description of the problem, the PS is suspect. And of course it could still be a logic board failure.

If you have another 2013 model, you can perhaps substitute parts to isolate the problem. Sometimes trouble shooting illusive problems can be lots of work. But as a tech, you already know that.

hi again

I switched the psu from my known good one.

and the issue remains.

but ive noticed the chime is now sort of doing a full chime then looping the start of the chime over and over until I unplug it.

im starting to thing the logic board is bad despite it sometime firing up correctly and showing me the question mark folder

 

[chscag]

im starting to thing the logic board is bad despite it sometime firing up correctly and showing me the question mark folder

It's beginning to look that way. Any chance you can swap the board out with a known good one?

 

[jasongoldworthy]

It's beginning to look that way. Any chance you can swap the board out with a known good one?

I believe mine is the same model just a different CPU and better GPU it should be ok in theory ??

ive tested the PSU with mine from the one that don't chime.

and its working fine.

 

[jasongoldworthy]

hi again a further update ive sourced a replacement logic board complete with cpu and heatsink and also a psu for £125 here in the uk shipped

you can never have enough spare psu's

but at least ill have it up and running again in a day or so.

ill post back my findings with a replacement logic board.

 

[chscag]

Sounds like a good plan and the £125 price is good for what you'll be getting. Keep us updated.

 

[jasongoldworthy]

Sounds like a good plan and the £125 price is good for what you'll be getting. Keep us updated.

Thanks buddy I will do

 

[jasongoldworthy]

Sounds like a good plan and the £125 price is good for what you'll be getting. Keep us updated.

hi again

replacement logic board arrived today with a spare PSU

installed just the logic board (original ram and blade drive)

and it fired up to Mac OS Catalina.

so its now solved...

thanks for all the help

jason

 

[chscag]

Good news, and good job. Thanks for letting us know.

 

[jasongoldworthy]

Good news, and good job. Thanks for letting us know.

Well as I said logic board solved the issue

shame the PSU I got was damaged they tore the connector off for the flex cable.

I doubt that can be fixed ?

 

[chscag]

I doubt that can be fixed ?

You might be able to repair it with the right tools. But generally, it's a lot easier to just replace the entire flex cable.

 

[jasongoldworthy]

You might be able to repair it with the right tools. But generally, it's a lot easier to just replace the entire flex cable.

hi again

ill try and attach the damage now.

the area circled is where the socket is damaged I don't know if I can fix that ??