MacBook Pro a1286 mid-2012 820-3330 No Wifi Hardware detected

pezter22

New member
I recently bought this 2012 MBP 15" 820-3330-b that had the no wifi hardware detected error.

I replaced Q3550 and L3504 but my readings remain similar on all the pieces next to the wifi connector. On Q3550 I know pin 3 (P3V3WLAN_SS) should be reading higher which is why I replaced it from a donor board.

Could it be R3550? I'm getting 32.7 Ohm and on diode mode pin 1 is OL and pin 2 is 1.04v.
1. P3V3WLAN_SS - 003v
2. PM_WLAN_EN_L - .002v

PP3V3_S3 - 3.35v
P3V3WLAN_SS - 003v
PP3V3_WLAN_R - 3.35v
P3V3WLAN_SS - 003v
PM_WLAN_EN_L - .002v
PP3V3_WLAN - .261v
WIFI_EVENT_L - .221v
PP3V3_WLAN_F - .185

Any help would be greatly appreciated.
 

2informaticos

Administrator
Staff member
"On Q3550 I know pin 3 (P3V3WLAN_SS) should be reading higher"
Who told you that???
You should know first how a MOSFET works; a P-channel in this case.
STOP to make wrong assumptions in the future!

"PP3V3_WLAN_R - 3.35v"
Any reason to touch Q3550, if it gives output voltage???

"PP3V3_WLAN_F - .185"
XW3552 is corroded; open trace, didn't check it?

Please, do NOT write the end "V" for diode mode readings in the future.
 

pezter22

New member
Okay. I'm still learning.
As far as XW3552 that isn't present on the board. However a test pad is.
TP(1)PP3V3_WLAN_R XW3552 is reading 3.32
I checked continuity from the test pad to Q3550 pin 4 and C3550 pin 1 is present.
 

2informaticos

Administrator
Staff member
XW3552 bridge is between Q3550 and L3504.
"PP3V3_WLAN_R - 3.35v
--------
PP3V3_WLAN_F - .185"
Does this look like continuity???
Run a tiny wire there...
 

pezter22

New member
I ran a jumper from L3504 (PP3V3_WLAN_F) to Q3550 (PP3V3_WLAN_R) and now get 3.35v, but still no wifi hardware showing up in network pref. I do get Bluetooth, so card is connected.

However from pin 3 on Q3550 I am still getting 0v. I realize you said it's a mosfet but power is not going to other parts.

L3504
PP3V3_WLAN - 3.32v
PP3V3_WLAN_F - 3.32v

At C3550 reading 51.5kOhms
PP3v3_WLAN_R - 3.32v
PP3V3WLAN_SS - 0v

C3551
PP3V3_S3 - 3.32v
P3V3WLAN_SS - 0v

R3550
P3V3WLAN_SS - 0v
PM_WLAN_EN_L - 0v

I have changed different wifi card and flex cables all with similar readings.
 

2informaticos

Administrator
Staff member
Still concerned with Q3550 :(.
Why, if already got correct L3504 voltage???

I can only repeat myself...
"You should know first how a MOSFET works; a P-channel in this case."
Google may help you.

Now post all U3540 voltages (airport connected).
 

pezter22

New member
I know how a mosfet works, what my question was is why nothing is passing through.

I turned the board over with airport card connected, attached the magsafe and heard a pop. I do not have 3v or 5v rails.

I have green light. I am going to have to track this down. So this is done for the time being until I find the piece that shorted.
 

pezter22

New member
Okay changed DC-in

U3540 with Airport card connected.

PP3V3_S3 - 3.32v
P3V3WLAN_VMON - .995v
AP_RESET_L - 3.32v
AP_RESET_CONN_L - 3.22v
GND
AP_PWR_EN - 3.32v
AP_CLKREQ_Q_L- 3.32v
AP_CLKREQ_L - 3.32v
 

pezter22

New member
R3554 is jumping around when I do an Ohms reading. 178k to 192k jumping.

PP3V3_WLAN_F - 3.32v
P3V3WLAN_VMON - .995v
 

2informaticos

Administrator
Staff member
"I know how a mosfet works, what my question was is why nothing is passing through."
You've said to get correct L3504 voltage; how "nothing is passing through" now?
"I ran a jumper from L3504 (PP3V3_WLAN_F) to Q3550 (PP3V3_WLAN_R) and now get 3.35v"

Just to let the things clear:
P3V3WLAN_SS must be 0V to get 3V at L3504.
Stop to bother you with Q3550, once you've got that voltage.

"AP_RESET_CONN_L - 3.22v
-------
AP_CLKREQ_Q_L- 3.32v
AP_CLKREQ_L - 3.32v"
All these bad; did you check with airport card connected?
 

pezter22

New member
Both reading zero with card now connected. Previous without after plugging in different DC-in board.

AP_CLKREQ_Q_L- 0v
AP_CLKREQ_L - 0v"
 

2informaticos

Administrator
Staff member
That's good.
Just to confirm, post again all U3540 pins voltage.
Check if L3501 is good.
Also check R3510/11 and C3530/31.

For the future, do not measure voltages for airport, SSD, or LCD, if corresponding device is not connected.
 

pezter22

New member
Sorry to take your day for this...

I did find that L3501 had fallen off at one point of the day (it was there earlier). I replaced it and am getting .372v on all four contacts
PCIE_CLK100M_AP_CONN_N - .372v
PCIE_CLK100M_AP_N - .372v
PCIE_CLK100_AP_P - .372v
PCIE_CLK100_AP_CONN_P - .372v

With airport card connected.

R3510
PCIE_AP_D2R_R_P - 0v
PCIE_AP_D2R_P 0v

R3511
PCIE_AP_D2R_R_N - 0v
PCIE_AP_D2R_N - 0v

C3530
PCIE_AP_R2D_N - .153v
PCIE_AP_R2D_C_N - .524v

C3531
PCIE_AP_R2D_P - .153v
PCIE_AP_R2D_C_P - .534v
 

pezter22

New member
FIXED! I have WIFI!

I guess after the earlier jumper wire installed between L3504 and Q3550 had worked. It was just that L3501 had been knocked off during my many times moving the board around.

Thank-you again for your efforts. Thank-you for having patience with a newbie.
 

2informaticos

Administrator
Staff member
No need to check voltage, these are data lines.
Diode mode readings can help.
But I mentioned them just to check if all are there.

For L3501, I was expecting to check its continuity; not voltage, nor even diode mode.
 
Top