Hi all
Got an IMAC 27" with a backlight fault.
Screen always lights up perfect for a few seconds on boot. After a few seconds, backlight goes off, machine is still running fine, you can see it if you look close enough.
Now I've read about a common fault with these where half the backlight goes off and flickers and what not and this is due to a connector on the panel itself. But this fault looks a little different than what I'm getting. Here is a vid showing that fault and the cause.
My fault I am currently leaning towards this being a LED driver board problem, specifically the caps on that board. Here is a pic of the inverter board http://www.macplus24.de/media/catal...db753da6cd7499147ede0ca58848/d/s/dsc_7630.jpg
There are 4 electrolytic caps on that board. The ones on the one I'm repairing don't look bulging or anything, although on the board, their solder joints, some look a little oxidised and there appears to be what looks a bit like flux residue around them. Is this a sign they have blown?
I'm thinking it couldn't hurt to replace those, my theory being, the caps allow the backlight to come on but due to their problem, don't allow it to stay on. And hence why turning it off and on again resolves it for a few seconds i.e. the cap gets drained and is able to perform ok again for initial start up or something like that?.
The main PSU caps all look good really, nothing worth comment that I can tell.
Thanks for any help guys
Got an IMAC 27" with a backlight fault.
Screen always lights up perfect for a few seconds on boot. After a few seconds, backlight goes off, machine is still running fine, you can see it if you look close enough.
Now I've read about a common fault with these where half the backlight goes off and flickers and what not and this is due to a connector on the panel itself. But this fault looks a little different than what I'm getting. Here is a vid showing that fault and the cause.
My fault I am currently leaning towards this being a LED driver board problem, specifically the caps on that board. Here is a pic of the inverter board http://www.macplus24.de/media/catal...db753da6cd7499147ede0ca58848/d/s/dsc_7630.jpg
There are 4 electrolytic caps on that board. The ones on the one I'm repairing don't look bulging or anything, although on the board, their solder joints, some look a little oxidised and there appears to be what looks a bit like flux residue around them. Is this a sign they have blown?
I'm thinking it couldn't hurt to replace those, my theory being, the caps allow the backlight to come on but due to their problem, don't allow it to stay on. And hence why turning it off and on again resolves it for a few seconds i.e. the cap gets drained and is able to perform ok again for initial start up or something like that?.
The main PSU caps all look good really, nothing worth comment that I can tell.
Thanks for any help guys