[help]imac 21,5 a1311 820-2641! is it a kind of magic?

i don't know how to explain it....never seen a problem like this

one led

as soon as i push the power button, the led disappear.

i've discovered that the imac can boot without problem, removing the wifi card.

i've tried another wifi card: the same.
i've tried another power supply: the same
any idea????


i've found a very old thread with the same problem, apparently with no solution..

Inspect and clean J3400 slot.
Check diode mode to ground at pins 2 & 6, w/ w/o airport card inserted.

If all good, remove Q3470 and test again if starts.

pin 6 has super low value (0,043), if i inject 1v i have 0,032 draw

Low reading w/ or w/o card inserted?

Possibly problem on 1V5_S0_MINI power rail.
You should compare with good board.

without card.

i have another imac with a similar board, and the value it's normal (like 0,550)

All the rails derived from 1V5_S0 appear on page 6.
You should follow them and try disconnecting components, until get correct reading.

i made a mistake: motherboard is 820-3126