820-2828-A

[2click]

Hi, this is the first iMac that I get to repair so I don´t really know where to start. It powers on but sometimes it shows image on the screen, replaced the EG card with a working known one and it didn´t show image, the I have 2 leds on on the board, the last 2 doesn´t turn on. Where should I start? thank you!

 

[2informaticos]

Tell us which coils get voltage.

Any history available?
Did you try known good power supply?

 

[2click]

Hi the board turns on fine, it chimes and loads system, so far I´ve tried another powersupply another inverter card and another lcd with the same result, when I turn it on it chimes but I have no image on the screen... When I tried a known good video card it showed image and booted to the login screen, but I turned it off. The next time I turned it on, it didn´t show image. What should I check first?

 

[2informaticos]

So original graphics card never gets image?
Did you check external video, when no internal image?

 

[2informaticos]

Test with both internal LCD and external monitor connected.
If video fails on external monitor at same time, there is a GPU related problem.