[SOLVED]820-00045 no TPAD or KB

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G.Beard

New member
This board was an insurance write off, I can't remember the history it's been in the draw.

Tried new trackpad and keyboard cable and new trackpad. KB powers machine.

J4801 voltages.
Pins:
1 = 3V3
3 = 3V3
5 = gnd
7 = 2V28
9 = 3V3
11 = 0V
13 = 0V1
15 = 3V3
17 = gnd
19 = gnd
21 = 3V3
23 = 5V
25 = 5V
27 = gnd
29 = gnd
31 = gnd
33 = gnd
35 = 8V6
37 = 8V6
39 = 8V6
41 = 8V6

2 = 0V
4 = 0V
6 = 0V
8 = 3V27
10 = 3V3
12 = 0V
14 = 5V
16 = 3V3
18 = gnd
20 = 0V
22 = 3V3
24 = 5V
26 = 3V3
28 = gnd
30 = gnd
32 = gnd
34 = 0V
36 = 8V6
38 = 8V6
40 = 8V6
 

aprendiz

Moderator
TPAD_SPI_MOSI should be 3.3V, it has a pull up resistor, check R4801 and R1667, SMC_ACTUATOR_DISABLE_L should be 3.4V this comes from SMC, measure in diode mode red probe to ground
 

G.Beard

New member
TPAD_SPI_MOSI should be 3.3V, it has a pull up resistor, check R4801 and R1667, SMC_ACTUATOR_DISABLE_L should be 3.4V this comes from SMC, measure in diode mode red probe to ground

R1667 on 3V3_S0 side is 3V3 but on TPAD_SPI_MOSI side = 0V.
Connection good R1667 to 3V3_S0
Connection good from R1667 to R4801. Also checked for short to gnd, no short.
R1667 = 46k

SMC_ACTUATOR_DISABLE_L = 0v and diode mode to gnd = 0.7V
 

G.Beard

New member
Did you try new TP/KB and cables. I'm not sure if a working keyboard is needed to make TP work.

Tried cables and keyboard did cross my mind but I only have one other definitely fucked keyboard for this machine. I'll put it back in the draw till something comes along to test the possibility of needing a KB for TPAD to work
 

dukefawks

Administrator
Keyboard can be fucked as long as the electronics in it are ok. There is a controller on the KB and sleep sensor too.
 

G.Beard

New member
Note to self: when buying after-market cables always buy more than one.

It was a bad cable. I have fitted another and it works.
Please mark solved.
 
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