Flickering Display

krbmedia

Registered
I have an original iMac intel with a flickering display. With an external monitor, the picture is perfect and I already swapped out the ram and no change. Any ideas on what could cause it? They are hell to open up (especially reconnecting the screws that secure the display, but if I have to :)....
 

DeltaMac

Tech
Could the problem be the inverter - which controls the backlight?
Turn the brightness on the display all the way down.
Is the flashing still appearing? Not sure if the iMac display will go completely off at minimum brightness, but you will still see the image on the display.
Is the flashing consistent across the screen, and not limited to a corner, or in a vertical strip, etc?
If you no longer see the flashing at minimum brightness, then you could try replacing the inverter board.
If you always see flashing, no change at different brightness levels, and the external display works fine, then likely a problem in the LCD panel, and you will need to replace the LCD panel.
 
Last edited:

krbmedia

Registered
Could the problem be the inverter - which controls the backlight?
No idea :)

Turn the brightness on the display all the way down.
Is the flashing still appearing? Not sure if the iMac display will go completely off at minimum brightness, but you will still see the image on the display.
No difference

Is the flashing consistent across the screen, and not limited to a corner, or in a vertical strip, etc?
Consistent, like a shimmering.

If you no longer see the flashing at minimum brightness, then you could try replacing the inverter board.
If you always see flashing, no change at different brightness levels, and the external display works fine, then likely a problem in the LCD panel, and you will need to replace the LCD panel.
Is there a certain wire I should check and tighten?
 

DeltaMac

Tech
You can try pulling the display panel out. Reseat the ribbon cable that connects to the back of the display panel.
You can try replacing that video ribbon cable. I suspect that won't fix the issue.
That leaves you with replacing the LCD panel, or, most likely, the logic board.
On a 10-year-old system, you could also try "cooking" the board to reflow the solder. It's just a try, so don't expect much from that.
Other than that - it will be (much) easier to find a full replacement, similar iMac on eBay, or your own favorite site for buying old Macs.
I would likely look for an iMac a year or two newer. Should still be good price, but much more capable processor, and you may even get one that has a separately replaceable graphics card (not on the oldest models...) which would make this kind of repair somewhat more likely to succeed :D
 

DeltaMac

Tech
I hear you. Been there, done that :D
You absolutely need a magnetic tip driver (with the T10 tip) for those screws.
That job would be incredibly frustrating without a magnetic tip driver.

Worst part for me is peeling all that black tape back from around the edge of the display.
 
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