820-01598 thermal sensor issue

[kjchatman1]

the board does just like the older mac board used to do. The fan slowly ramps to full speed and it's laggy. Is there an smc bypass procedure for the newer models?

 

[2informaticos]

Do you have known good battery connected?

 

[kjchatman1]

the battery is good

 

[2informaticos]

Start in diagnostic mode and check what errors pop up.

 

[kjchatman1]

pfm006.

 

[2informaticos]

Test with known good trackpad board/flex.
Also try disconnecting camera flex from T-CON.

 

[kjchatman1]

diode mode to ground on i2c_tpad_3v3_scl is 1.466 and i2c_tpad_3v3_sda is 0.958 . i remember you telling me that the readings on a data bus line should almost match.

 

[2informaticos]

Too big difference; check on the other side of Q6861 too.
Inspect R6877/8 and R6812/3.

Did you check in diode mode w/ and w/o trackpad connected?

 

[kjchatman1]

those reading are without the trackpad cable connected. i2c_tpad_3v3_sda reads the same on a known working board. i2c_sense_scl seems to be culprit. I2c_sense_scl is 1.992 and i2c_sense_sda is 0.471 in diode mode to ground

 

[kjchatman1]

do you know if u3900 has one or two layers of solder on this model? i'll attempt to reball it if there is just one

 

[2informaticos]

T2 is a sandwich chip.

 

[kjchatman1]

i've replaced that u3900 chip with another one. now the amp meter shows 20v 0.000a with a charged battery

 

[2informaticos]

You should use SoC ROM (U4770) from the same board of the "new" T2.
Also need DFU restore.

 

[kjchatman1]

when jumpering soc_force_dfu, can i solder the jumper before applying power or only after applying power?

 

[2informaticos]

You must solder wire before applying power.
Cut it off as soon as machine enters into DFU mode.