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820-3476 no left shift function

Repairable

Repairable

Active member
Hi all,

got this in had liqued damage all cleaned and the thing was running fine,
now it came back, seems left shift wont work.
changed 3 keyboards, changed TP cable and TP

stil same... all works except left shift
 
D

dukefawks

Administrator
Why would you change the trackpad and cable? I really want to understand the reasoning behind this.

Left shift is a separate key on pin 3 of the connector. Measure if it is pulled low when shift is pressed. I have a feeling left control and left option are also not working. Look at U4850 circuit and understand how this works.
 
Repairable

Repairable

Active member
dukefawks said:
Why would you change the trackpad and cable? I really want to understand the reasoning behind this.

Left shift is a separate key on pin 3 of the connector. Measure if it is pulled low when shift is pressed. I have a feeling left control and left option are also not working. Look at U4850 circuit and understand how this works.
Click to expand...

because i wanted to make sure the trackpad/TPcable had no influence on this (yes they are separate on the board.so they should not)

.
 
Repairable

Repairable

Active member
U4850 question, when pressing Left shift, WS_LEFT_SHIFT_KBD goes low U4850 (wil send out signal on WS_LEFT_SHIFT_KEY (have not checked if this signal is high or low when not pressed/and pressed machine needs to get send out)
but if WS_LEFT_SHIFT_KBD goes low when pressed, and U4850 wont send out any change and U4850 does get PP3V42_G3H U4850 most likly is fucked

for this issue only WS_LEFT_SHIFT_KBD was affected
so U4850 was good, when pressing the button it did go low at 1 side of the board. other side did nothing.
 
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