A1278 820-2533-B no wifi


I have an A1278 820-2533-B that had liquid contact and has no wifi. It has a burnt L3404, L3401, and some surroundig caps. I don't have any 820-2533-B to steal those parts. Can I use those parts from any other board?



I don't think i have a short in PP5V_WLAN. (OL in diode reading).

Just to be sure, i should jumper L3404 pin 1 to C3422 pin 1, correct?
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Tks. That's what I've done, I have 5V on PP5V_WLAN , but still no wifi. It says no hardware present.
I'm not sure if i had to have continuity from L3401 (pin1) PCIE_CLK100M_MINI_CONN_N to C3422 PP5V_WLAN, but i don't have it.
Can it be U3402 (I have 3.3V on PP3V3_S3)? How can i check it?
What should I check now. Can you help?
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Just realized that the wire that i've jumped has "exploded" / breaked after a few reboots.
It seams that i have a short on the airport. With the airport cable connected, i get 0.002 in diode readings, and 0.5 ohm to ground on PP5V_WLAN . Can i check anything else?
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Staff member
Airport card, or cable.
Disconnect airport card on the other side of the cable.
See where the short remains.
I'm sorry. I've write the wrong model. It is an 1286 820-2533-B model.
The cable goes right to the interior of the display. Is there a card inside?
Tks. Didn't know that.
The cable was presured by a screw. After disassembling it, the short has gone.
Now I have 5V on PP5V_WLAN and 0.504 in diode mode, and 50kohm to ground, but no wifi yet.