A1278 820-2533-B no wifi

hgoncalves

Active member
Hi,

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?

TKS
 

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hgoncalves

Active member
Actualy, it seams that only L3404 had exploded. However, the pads are gone.

Is there any way to fix this pads? If so, can i use other part from other board?
 

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hgoncalves

Active member
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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hgoncalves

Active member
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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hgoncalves

Active member
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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2informaticos

Administrator
Staff member
Airport card, or cable.
Disconnect airport card on the other side of the cable.
See where the short remains.
 

hgoncalves

Active member
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?
 

hgoncalves

Active member
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.
 

hgoncalves

Active member
Hi,
Today, i managed to find a display (with the wifi) for this model, and when i was trying it, the mac doesn't power on.
I have a missing PP5V_S3 and PP3V3_S5 voltage. I look at L3405 (the jumper was near to it) and it seams ok, and can't find any missing components..
Can you help?
 
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hgoncalves

Active member
Hi, no it doesn't. However, I saw that c2511, c2581 and c2580 were knocked out.

Because i have no other 820-2533-B board, I've replaced them for 2x 16V X7R 100nF +- 10% caps (C2511 and C2581) and one 10V XR5 470nF +-10% (C2580) cap. Not sure if they are compatible. Are they?

Stil dosen't power on.
 
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