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KnobKylan

macrumors newbie
Original poster
Jan 14, 2021
5
2
Hi all, first please be kind... I attempted a search for this problem but wasn't successful in narrowing it down. I recently replaced the original HDD with SSD on a mid-2011 iMac 21.5" a1311. Once I buttoned everything up, it wouldn't power up. I retraced my steps and found once the LCD panel was completely unplugged, everything (fans, optical drive etc) started up. As soon as I reconnected all cables to LCD, no start up whatsoever. Wondering if there was short in the LCD or perhaps damage to the cables connected to the LCD. Any ideas? I know I can source a panel for relatively cheap, but I'd prefer troubleshoot all possible options before wasting $$. Thank you!
 

Nguyen Duc Hieu

macrumors 68040
Jul 5, 2020
3,020
1,006
Ho Chi Minh City, Vietnam
Hi all, first please be kind... I attempted a search for this problem but wasn't successful in narrowing it down. I recently replaced the original HDD with SSD on a mid-2011 iMac 21.5" a1311. Once I buttoned everything up, it wouldn't power up. I retraced my steps and found once the LCD panel was completely unplugged, everything (fans, optical drive etc) started up. As soon as I reconnected all cables to LCD, no start up whatsoever. Wondering if there was short in the LCD or perhaps damage to the cables connected to the LCD. Any ideas? I know I can source a panel for relatively cheap, but I'd prefer troubleshoot all possible options before wasting $$. Thank you!

Check the cables of the LCD panel. Many users simply broke or twisted some parts of the cable and causing the short circuit.
 

KnobKylan

macrumors newbie
Original poster
Jan 14, 2021
5
2
Check the cables of the LCD panel. Many users simply broke or twisted some parts of the cable and causing the short circuit.
Thank you for the feedback! I went and carefully re-seated each of the four cables attached to the panel, unplugging power and powering back on between each, the only non-start up was when the lcd cable was attached. I assume this is the cable that is shorting out. Hoping for a cable issue and not the seat on the logic board. Cable delivers in a couple of days.
 

USB3foriMac

macrumors 6502
Apr 15, 2020
317
119
Singapore
Hi all, first please be kind... I attempted a search for this problem but wasn't successful in narrowing it down. I recently replaced the original HDD with SSD on a mid-2011 iMac 21.5" a1311. Once I buttoned everything up, it wouldn't power up.
Before you are disappointed that a new cable doesn't help, maybe describe in more details what your procedure was:
- You removed the front screen (provide photo of connectors on screen and board, there are different versions)
- You removed the HDD (i.e. you did not remove any other part of the internals)
- You put in the SSD
- You did not do any mod for temp sensor, or did you?
- Then you tested or not?
- Then you connected the screen, then nothing works?

You are apparently not aware that the original HDD has a special temperature sensor built-in, which other drives do not have. As a result, fans spin up to the maximum after powering up. To address this, you can either use a software solution like MacsFanControl, or a SATA splitter, or a small hardware mod on pins 11/12 of the SSD. See here for hardware mod and SATA splitter.
 

KnobKylan

macrumors newbie
Original poster
Jan 14, 2021
5
2
Before you are disappointed that a new cable doesn't help, maybe describe in more details what your procedure was:
- You removed the front screen (provide photo of connectors on screen and board, there are different versions)
- You removed the HDD (i.e. you did not remove any other part of the internals)
- You put in the SSD
- You did not do any mod for temp sensor, or did you?
- Then you tested or not?
- Then you connected the screen, then nothing works?

You are apparently not aware that the original HDD has a special temperature sensor built-in, which other drives do not have. As a result, fans spin up to the maximum after powering up. To address this, you can either use a software solution like MacsFanControl, or a SATA splitter, or a small hardware mod on pins 11/12 of the SSD. See here for hardware mod and SATA splitter.
I have the appropriate temp sensor installed correctly.
 

KnobKylan

macrumors newbie
Original poster
Jan 14, 2021
5
2
New LCD cable arrived, installed, same issue. Rig starts up with no issues with all lcd wires attached with the exception of the actual LCD cable. So I either damaged the LCD cable again when reinstalling (highly probable because the angle and ease of seating/my fat hands makes it a ham handed affair), or there is something wrong with the LCD itself. Ordered two more LCD cables and a replacement LCD. It has to be the cable, which is apparently incredibly sensitive from what I have been reading, or the damaged cable perhaps damaged the LCD itself, some sort of short. More money, but I will continue to tinker until I figure it out.
 
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USB3foriMac

macrumors 6502
Apr 15, 2020
317
119
Singapore
New LCD cable arrived, installed, same issue. Rig starts up with no issues with all lcd wires attached with the exception of the actual LCD cable. So I either damaged the LCD cable again when reinstalling (highly probable because the angle and ease of seating/my fat hands makes it a ham handed affair), or there is something wrong with the LCD itself. Ordered two more LCD cables and a replacement LCD. It has to be the cable, which is apparently incredibly sensitive from what I have been reading, or the damaged cable perhaps damaged the LCD itself, some sort of short. More money, but I will continue to tinker until I figure it out.
It would still help if you describe exactly what exactly you did.

Also, your damage can well be on the logic board. Take close up pictures of the LCD connector you are suspecting - on the logic board side. Maybe we can see something wrong with this.
 
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