820-2850A No Bluetooth

[Ictc]

I have this old machine that runs perfectly except for the BT wich is not showed in the os. I tried different OS before taking the mobo out. I swapped the BT/WiFi module with another one and still the same. Wifi works, USB works as well but no BT. I cheched the path from J3401 to U3700 and it's fine and consistent. PP3V3_S3_BT_F is also present (3,29v). on USB_BT_N I measure about 0,32V and on USB_BT_P I get about 0,30V. Trackpad and camera are fine too.
Any suggestion about what else I should have look for?

 

[2informaticos]

Did you try another cable for WiFi-Bluetooth module?

 

[Ictc]

Yes other two which I didn’t test before but I assume can’t be both faulty in the same identical way...

 

[2informaticos]

Be sure L3403/06 have practically 0 ohm.
Compare diode mode to ground and voltage on USB_BT lines with working board.
Be sure to have good contacts on J3401 pins.
Change U3700, just in case.

 

[Ictc]

compared voltage drops with other boards with graphics issues but no known BT issues and couldn’t find any difference. I also swapped U3700 with no luck. Swapped in total 3 flats and wifi modules with no differences. I see the WiFi but the BT still not showing up in the system resources. I also ran windows to see if could have been an os related problem but this was not the case. Still a mystery, I don’t know where to look for and what to blame so far.

 

[2informaticos]

Try to bypass airoport connector on the MLB.
Solder two wires directly between bluetooth module and MLB...

 

[Ictc]

At this point should I blame the pch side? Is there a way to know if the two signals coming from the usb hub 2 reaches U1800?

 

[Ictc]

Try to bypass airoport connector on the MLB.
Solder two wires directly between bluetooth module and MLB...

You mean I need to route back those two signal from the connector? Is there perhaps any schematic to check for in order to provide also power to the ext airport module? I’ll try to sort this out. Thank you

 

[2informaticos]

You will also keep connected airport in the MLB, to provide power.
Just bypass data lines, to discard bad contacts on J3401.

You can also redirect data lines of bluetooth to SD Card inputs of USB Hub.
You must separate the lines, of course.