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A1706 emc3163 touch bar not working after display replacement.

M

manumathew.017

Member
Hi,
I have replaced the display panel, Not the full display assembly but just the panel alone, I don't know the reason. The board boots perfectly, It passes the diagnostic test without any error. But the touch panel is not glowing.

Some history:- While removing the display I have disturbed the ribbon cable near the webcam, I think it's broken a little.
 
2informaticos

2informaticos

Administrator
Staff member
820-xxxxx board code?

Do you note the tocuh bar is working, but missing backlight?
Keyboard backlight works correctly?
 
M

manumathew.017

Member
It must be 820-00239-09,
But I don't see a keyboard backlight, But the keyboard is working. The touch bar is not working at all, I mean no response no backlight.
 
2informaticos

2informaticos

Administrator
Staff member
Ambient Light Sensor is integrated into webcam electronics.
In your case, ALS is good I suppose, just damaged connection through flex.
 
2informaticos

2informaticos

Administrator
Staff member
Re-check all your work in this machine.
Test the board alone on the desk.
Check for knocked off components, or damaged traces.
 
M

manumathew.017

Member
Removed the board and checked, The PPBUS_G3H has 2 ohms resistance with respect to ground. But couldn't understand who is causing the short. And the current consumption of the board is 20V and approximately 40mA (May is not accurate)
 
2informaticos

2informaticos

Administrator
Staff member
I hope you've checked resistance to ground without power.
Compare that value with resistance to ground on all coils.
 
M

manumathew.017

Member
Yes I have measured the resistance to ground without power.
Here are more measurements

L3500 - 636 Ohm
L8410 - 4.3 Mohm
L7030 - 1.23 Mohm
L7600 - 0.6 Mohm
L7660 -1.6Mohm

L7430 - 2 Ohm
L7420 - 2Ohm
L7410 - 2 Ohm

L7210 - 4.2 Ohm
L7220 - 4.2Ohm

L7270 -6.7Ohm
L8000 - 89.7 Ohm
L8050 - 69.3Ohm
L7900 - 245 Ohm
L7960 - 50 Ohm
LB700 -1.6K Ohm
L9400 - 3.1KOhm
 
M

manumathew.017

Member
For more clarity putting the diode mode measurement also along with this

L3500 - 636 Ohm - 0.222V
L8410 - 4.3 Mohm - 0.837V
L7030 - 1.23 Mohm - 0.415V
L7600 - 0.6 Mohm - 0.415V
L7660 -1.6Mohm - 0.359V

L7430 - 2 Ohm - 0.002V
L7420 - 2Ohm - 0.002V
L7410 - 2 Ohm - 0.002V

L7210 - 4.2 Ohm - 0.004V
L7220 - 4.2Ohm - 0.004V

L7270 -6.7Ohm -0.006V
L8000 - 89.7 Ohm - 0.071V
L8050 - 69.3Ohm - 0.061V
L7900 - 245 Ohm - 0.0153V
L7960 - 50 Ohm - - 0.050V
LB700 -1.6K Ohm - 0.232V
L9400 - 3.1KOhm - 0.381V
 
M

manumathew.017

Member
Sorry Just noticed that
After removing the inductor's Load side is 1.6 Ohm (2nd pins of all three inductors).
L7430 1st pin - 1.017K
L7420 1st pin - 425 Ohm
L7410 1st pin - 1.017K
 
Last edited:
2informaticos

2informaticos

Administrator
Staff member
There is no short on CPU side, just normal value.
I said one chip is shorted between PPBUS_G3H and one CPU coil.
You've removed all three, how do you know which is the culprit now???
Need to check between the pins of each chip, outside of the board, to find the bad one.

BTW, you can see no short to ground on PPBUS_G3H now.
 
M

manumathew.017

Member
I have removed the three inductors and measured the resistance at 1st and 2nd pin of the inductors.
2nd pin of all the inductors are 1.8 ohm .

1st pin resistance are below.

L7430 1st pin - 1.017K
L7420 1st pin - 425 Ohm
L7410 1st pin - 1.017K
.......

Please ignore what I did, do you have any suggestions to figure out which chip is causing the issue?
 
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