Help with late 2008 Imac!!!!.

[Hidden1972]

Hi everyone.

I'm new to the forum.
I'm having a problem with my late 2008 "8.1" Imac and I wanted to know if anyone can shed some light. The problem has been occurring ever since I updated the OS. I had "El Capitan" installed and I updated it to "Catalina" with the patch from "dosdude1", everything seemed to be going well that day until I left the house for a while and left the Imac on and when I came back the screen was black and unresponsive. I turned off the Imac from the button and now when I turn it on the "Gong" sounds but nothing else, the fans don't sound and the screen is still black. It seems like a hardware problem, but I wanted to know if you can think of what could be wrong. I've tried all the keyboard combinations I've seen on the web to solve problems and it's still the same.
Thanks to everyone in advance.

Greetings.

 

[Fishrrman]

Hardware failure inside?
After all, it's going on 17 years old.

You might start "considering your options" and look around at what's new.

Did you create a bootable flashdrive with the dosdude software?
If so, have you tried booting from that?

 

[DeltaMac]

This would be a good time to have Apple's service manual! That will show you where the diagnostics LEDs are. You can see them immediately to the right of the memory slots. Just tip the iMac back so you can see up through the ventilation holes. You may need to remove the front bezel, but you don't usually need that off to see the LEDs.
There are 4 LEDs there. The first may be coming on, any time the power cord is plugged in. #2, 3 and 4 should light up after pressing and releasing the power button.
I suspect you will find that the power supply is not working properly, but you said that you get a boot chime, so, you probably won't get LEDs 3 or 4, which is likely that your video card has failed -- maybe the logic board.

 

[Hidden1972]

Hardware failure inside?
After all, it's going on 17 years old.

You might start "considering your options" and look around at what's new.

Did you create a bootable flashdrive with the dosdude software?
If so, have you tried booting from that?

Hi.

Thank's for your quick answer.
In did I can look for somthin newer, but is my mother's Imac and for internet she mahage better with this one or at least is what she saids. Also I like to trouble shut my sel so I can lear somthing else.

Regards.

 

[Hidden1972]

This would be a good time to have Apple's service manual! That will show you where the diagnostics LEDs are. You can see them immediately to the right of the memory slots. Just tip the iMac back so you can see up through the ventilation holes. You may need to remove the front bezel, but you don't usually need that off to see the LEDs.
There are 4 LEDs there. The first may be coming on, any time the power cord is plugged in. #2, 3 and 4 should light up after pressing and releasing the power button.
I suspect you will find that the power supply is not working properly, but you said that you get a boot chime, so, you probably won't get LEDs 3 or 4, which is likely that your video card has failed -- maybe the logic board.

Hi.

Thank's for your quick answer.
I looked to the Led's and I think it's onli 1,2 and 3, the 4th one doesn't do any thing. What can mean that error?.

Regards.

 

[PaulD-UK]

Screen problem, or cable to screen?

From iFixit:
LED 4 - Indicates that the computer and the LCD display panel are communicating. This LED will be ON when the computer is turned on and video signal is being generated. If the LED is ON and there is no image on the LCD display panel, the LCD display panel or inverter might be installed incorrectly or need replacement.

iMac Intel 24" EMC 2134 and 2211 Diagnostic LED's

The 24-inch 2007 and 2008 iMac's have four diagnostic LEDs on the logic board that can help troubleshoot the computer. A little disassembly is...

www.ifixit.com

 

[DeltaMac]

I think the likely problem is the inverter board, but that is not a separately replaceable part.
That board is part of the power supply (I think), so replacing the power supply should fix.
But, the inverter cable connects directly from the power supply to the back of the LCD panel.
So, there's another possibility for failure on the display panel itself.
Try the power supply first, as that is a more common failure point. If that does not fix, then it's the LCD panel.
(It's 17 years old. Parts fail from age.)

 

[PaulD-UK]

Some of these old model CFL screen panels had the inverter built into the screen panel.

 

[DeltaMac]

OK, thank you for the clarification!
But, the power supply is probably a better first step.

 

[Hidden1972]

Screen problem, or cable to screen?

From iFixit:
LED 4 - Indicates that the computer and the LCD display panel are communicating. This LED will be ON when the computer is turned on and video signal is being generated. If the LED is ON and there is no image on the LCD display panel, the LCD display panel or inverter might be installed incorrectly or need replacement.

iMac Intel 24" EMC 2134 and 2211 Diagnostic LED's

The 24-inch 2007 and 2008 iMac's have four diagnostic LEDs on the logic board that can help troubleshoot the computer. A little disassembly is...

www.ifixit.com

But if is an inverter failure. Why the gong sounds and the fans doen't work?.
Also I'd change some time ago the power supply.

 

[mreg376]

Hi everyone.

I'm new to the forum.
I'm having a problem with my late 2008 "8.1" Imac and I wanted to know if anyone can shed some light. The problem has been occurring ever since I updated the OS. I had "El Capitan" installed and I updated it to "Catalina" with the patch from "dosdude1", everything seemed to be going well that day until I left the house for a while and left the Imac on and when I came back the screen was black and unresponsive. I turned off the Imac from the button and now when I turn it on the "Gong" sounds but nothing else, the fans don't sound and the screen is still black. It seems like a hardware problem, but I wanted to know if you can think of what could be wrong. I've tried all the keyboard combinations I've seen on the web to solve problems and it's still the same.
Thanks to everyone in advance.

Greetings.

Welcome to the world of patching OS's not designed for your model Mac. Before you start monkeying around with the innards I would reinstall El Capitan and see if you still have the problem.

 

[DeltaMac]

Power supplies will still be close to 17 years old, tested, maybe repaired, but still will be old parts.
There's always some risk with the parts.
If you don't want to try the power supply, then start looking for a replacement LCD panel.

 

[Hidden1972]

Power supplies will still be close to 17 years old, tested, maybe repaired, but still will be old parts.
There's always some risk with the parts.
If you don't want to try the power supply, then start looking for a replacement LCD panel.

Hi.

Thank you very much.

Regards.

 

[Hidden1972]

Welcome to the world of patching OS's not designed for your model Mac. Before you start monkeying around with the innards I would reinstall El Capitan and see if you still have the problem.

Hi.

Thank you for your repply, but if ou read carefully my previous posts you will find out that the fan is not working, the Imac is not starting at all, so there's no chance to go back by any means to reinstal El Capitan.

Regards.

 

[Hidden1972]

Finally was a lose conection. Now works perfectly.