A2337 820-02016 No Keyboard or Trackpad

[it-solve]

Interesting case, I got two of these with same fault.

No liquid damage or sign of impact. Trackpad connector seems intact, no prior work.

Tested spare trackpad still no response.
Connected individually to eliminate the other and both Keyboard and Trackpad are not working together and independently.

JT400 Diode values on the pins seems normal.

 

[2informaticos]

"Keyboard and Trackpad are not working together and independently"
Keyboard can't work without trackpad.
So you probably have a trackpad problem.

If JT400 gets all correct power rails, then check page 76 circuitries.

 

[it-solve]

I am missing PPBUS_AON_IPD_FLT line all the way to UC850.

Measuring its feet I am getting a weird repetitive pulse down on PPBUS_AON - 12.3V which drops for a millisecond to 11.8V and resumes.
PPBUS_AONSW_IPD_EN pulsing to 0.25V

This with a bare board on the bench.

Looking under microscope seems like there was oxidation around 37,39.41 of JT400 at some point.

 

[2informaticos]

Do you get 3V3/5V_S2SW_IPD?
If yes, check RC852/70.

Just in case, check with trackpad connected.

 

[it-solve]

PP5V_S2SW_IPD - 0.07V
PP3V3_S2SW_IPD - 0V
PP3V3/5V_S2 lines present
IPD_PWR_EN_GATE - 0V


This with tpad connected and screen on

Strangely I am not able to turn this board without battery connected. Stays at 5V pulses 0-0.3A
With battery connected charges and runs well, is this something you are aware of?

Keyboard can't work without trackpad.

The reason why I said that was because I received another same model, where tpad won't work, but keyboard types. Tested spare tpad and cable and still wasn't working. Thats another case though.

 

[2informaticos]

"tpad won't work, but keyboard types"
Trackpad click works, but doesn't move the cursor?

Keyboard information pass through trackpad circuitries, on its way to CPU.

3V3/5V_S2SW_IPD rails have correct diode mode readings?

 

[it-solve]

"tpad won't work, but keyboard types"
Trackpad click works, but doesn't move the cursor?

Thats a different one I had, not this case. No click or cursor move on that one, just kbd types. Customer took for second opinion to Apple, wonder how that will go.

Looks ok, just strange that its pulsing. Usually, diode modes are steady.
3V3_S2SW_IPD - pulsing 0.3-0.7-1.2
5V_S2SW_IPD - pulsing 0.4-0.6-1.2

Compared with spare board, which has only a charging issue. Measurements match.

 

[2informaticos]

Check UR200 signals.

 

[it-solve]

IPD_LID_OPEN_R_1B8 - 1.8V
AMR_RIGHT_OR_ND_1V8 - ~ 1.48V
AMR_LEFT_OR_ND_1V8 - ~ 1.49V

 

[2informaticos]

Check UC861 signals.

 

[it-solve]

PP1V8 test point - 1.78V
P3V3_AND_P5V_IPD - 1.8V
PPBUS_AONSW_IPD - 1.78V
IPD_OCP_FLT - 0V / 0.377 which matches a reference board.

This seems ok for a nand gate

 

[2informaticos]

U8100 is suspect then...

 

[it-solve]

Did a DFU Restore, kept failing. On the 5th attempt succeeded.
Now have keyboard, but no trackpad functionality.

 

[2informaticos]

No click, no move?

 

[it-solve]

No click, no move

 

[2informaticos]

Really strange.
Both KB and TP info should pass to CPU via SPI_IPD bus.