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a1502 820-4924-A Liquid Damage... no image, but boots when Magsafe plugged in
- Thread starter papalati
- Start date
You should get similar values on both lines, you've posted a big difference.
That could be the reason of no backlight; as it is controlled through I2C_BKLT_SCL/SDA bus.
Are the last values taken with LCD connected?
In such case, pot voltages without LCD too.
R7050/51 must be 0 ohm and R7052/53 2.4K.
Sorry for misstyping, I meant SCL, not SCKA.
I can only use aprox 60% of my eyes...
That could be the reason of no backlight; as it is controlled through I2C_BKLT_SCL/SDA bus.
Are the last values taken with LCD connected?
In such case, pot voltages without LCD too.
R7050/51 must be 0 ohm and R7052/53 2.4K.
Sorry for misstyping, I meant SCL, not SCKA.
I can only use aprox 60% of my eyes...
Internal LCD is connected through eDP (Embedded Display Port), which is not related with external DP going through Thunderbolt.
As DP_INT_HPD stays high, and you get steady 5V at pins 28-30, PCH detects internal LCD correctly.
Very likely image is there, but not easy to detect.
Think what you did on the board, recheck all your job.
You had correct BKLT_SDA with 0V before.
The big difference on I2C_BKLT_SCL/SDA lines blocks the backlight now.
As DP_INT_HPD stays high, and you get steady 5V at pins 28-30, PCH detects internal LCD correctly.
Very likely image is there, but not easy to detect.
Think what you did on the board, recheck all your job.
You had correct BKLT_SDA with 0V before.
The big difference on I2C_BKLT_SCL/SDA lines blocks the backlight now.
papalati
Member
Well, I went back to check my work and as I was checking continuity on the lcd connector pins, it looks like i have a short to ground on I2C_BKLT_SCL.
Going to have to backtrack and try to find it. I'll try to tomorrow as it isn't my work as I removed the lcd connector and jumper wires and the short was still there.
Going to sleep it's been a long day.
Going to have to backtrack and try to find it. I'll try to tomorrow as it isn't my work as I removed the lcd connector and jumper wires and the short was still there.
Going to sleep it's been a long day.
"R7752/53 are not 2.4K they are 1.59k"
Is normal to get lower value indications for onboard measurments.
An o-scope can show if there is activity on I2C_BKLT_SCL/SDA and EDP_BKLT_PWM lines when backlight keys are pressed.
At least check if EDP_BKLT_PWM DC level varies.
DP_INT_HPD stays high?
Is normal to get lower value indications for onboard measurments.
An o-scope can show if there is activity on I2C_BKLT_SCL/SDA and EDP_BKLT_PWM lines when backlight keys are pressed.
At least check if EDP_BKLT_PWM DC level varies.
DP_INT_HPD stays high?