Hello,
I'm trying to repair an iMac A1418 (EMC 2638) which display fault.
Seems on cold boot display works fine but after a while begins to flickering to a black screen.
I tried an external monitor and it works, correctly.
The board is a 820-3588-A (files attached).
When the display is active and alive, I think all values are ok:
Diagnostic LED: #1 ON #2 ON #3 ON #4 ON
J8100
LED_RETURN_1 4,5V (sometimes 11,5V)
LED_RETURN_2 4,5V (sometimes 11,5V)
LED_RETURN_3 4,5V (sometimes 11,5V)
LED_RETURN_4 4,5V (sometimes 11,5V)
LED_RETURN_5 4,5V (sometimes 11,5V)
LED_RETURN_6 4,5V (sometimes 11,5V)
BKLT_BOOST_1 61,3V
BKLT_BOOST_2 61,4V
L440
PP12V_LCD_F 12,1V
PP12V_LCD 12,1V
When suddenly the display goes black, I have:
Diagnostic LED: #1 ON #2 ON #3 ON #4 OFF
J8100
All 0V
L440
PP12V_LCD_F 12,1V
PP12V_LCD 12,1V
VSYNC Cable with no sign of shorts.
Any hint?
Thanks
I'm trying to repair an iMac A1418 (EMC 2638) which display fault.
Seems on cold boot display works fine but after a while begins to flickering to a black screen.
I tried an external monitor and it works, correctly.
The board is a 820-3588-A (files attached).
When the display is active and alive, I think all values are ok:
Diagnostic LED: #1 ON #2 ON #3 ON #4 ON
J8100
LED_RETURN_1 4,5V (sometimes 11,5V)
LED_RETURN_2 4,5V (sometimes 11,5V)
LED_RETURN_3 4,5V (sometimes 11,5V)
LED_RETURN_4 4,5V (sometimes 11,5V)
LED_RETURN_5 4,5V (sometimes 11,5V)
LED_RETURN_6 4,5V (sometimes 11,5V)
BKLT_BOOST_1 61,3V
BKLT_BOOST_2 61,4V
L440
PP12V_LCD_F 12,1V
PP12V_LCD 12,1V
When suddenly the display goes black, I have:
Diagnostic LED: #1 ON #2 ON #3 ON #4 OFF
J8100
All 0V
L440
PP12V_LCD_F 12,1V
PP12V_LCD 12,1V
VSYNC Cable with no sign of shorts.
Any hint?
Thanks
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