iMac Screen Out?

[tacvbo]

My 2010 iMac screen does not turn on at all, but I hear iMac on. I can turn it off be pressing power button for seconds and I can turn it back on. Screen remains black. Is there anything I can do to fix it or it's done?

 

[DeltaMac]

Is the screen fully black - or do you see any parts of the screen image (login screen, or menus and icons from your normal desktop) even if very dim. That's easier to see if you shine a bright light into the screen. If you do see dim icons or other images, then you likely have a failed backlight board.
If the screen is really completely black - no menus, nothing, then you could try reseating the video cable.
You can also try connecting an external monitor to your iMac, if you have that available. If you get good video on the external, then you may have a failed LCD panel.

There ARE some LED diagnostic lights inside that can help you decide what you can do.
You can find a service manual for your iMac online somewhere. You can search for the name of the pdf.
example:

imac_21_mid10.pdf

(If you have a 27-inch, you just replace the 21 with 27 to search for the correct manual.
That will show you how to get at the diagnostic LEDs, and how to interpret them.

 

[tacvbo]

The screen is fully black.Tried the light and nothing seen. I connect an external monitor, but signal does not go through to it. I am wondering if there is something I can do or press to force that? Looked into the manual, but don't have the tools to open iMac from screen like I saw in a video. I was only able to open piece at the bottom, which I assume is the memory slots.

 

[mikehalloran]

Thy resetting the NV RAM. If that works or you get even a flicker, replacing the battery is your next step.

A black screen is a symptom of a bad NV RAM battery. Unfortunately, it’s on the back side of the motherboard of a late 2009–2010 and is a time consuming replacement. Use a CR2032. Around here, it’s a $75 labor charge, The iFixIt instructions are good.

If an external monitor won’t work, this is not a good sign.

There is little point in repairing a 2010. You can part it out or sell it for parts and use the proceeds to offset something newer.

 

[JedNZ]

My friends iMac has just done the same, and confirmed by the Apple authorised repairer that it’s the backlight that’s gone. The repairer said if we want to use an external monitor on it that we have to disable the backlight cable. Can anyone confirm that’s true - that you have to disable the backlight cable in order to just use the external monitor?

 

[tacvbo]

It seems like it could be what you were told since it seems like it is running just without screen. I could not get it to output to second monitor. Currently just sitting in the floor and hope to eventually attempt something and will look into how disabling the backlight cable is possible. Thanks.

 

[MCAsan]

Ask the local Apple store to diagnose and quote repair. You can always say no or trade it in towards a new Mac.

 

[JedNZ]

All went well hooking up the external monitor. To begin with it just down a black extended desktop, with a dulled out menu bar. But I was able to click on the Apple menu and then System Preferences and then click on Display and mirror monitors option.

And then... the internal monitor started working again!

Oh well, we’ll leave the external monitor connected on mirroring in the event the internal display and/or backlight craps out again.