A1706 820-00923 no image

[hgoncalves]

Hi,

I have an A1706 820-00923 with no image.

It has 20V on ampmeter, it reaches 1.45A, CPU gets hot, it seams to be powering on, but I have no internal image neither external.

Already tried a known good lcd, without success.

Can you help?

 

[2informaticos]

USB activity?
Why the peoples always check for image only?
CPU core voltage behavior???
Any history available?

 

[hgoncalves]

HI,

Sorry. After all, it seams that the LCD is working (tried it on another machine and it is OK), and It has external image, but no backlight on internal display, even with other LCD (something was making a bad contact, and after removing the board, it started to work).

EDP_BKLT_EN = 0V, and 0.545 on diode reading.

PP5V_S0_BKLT_A = 5.1V
PP5V_S0_BKLT_D = 5.1V
BKLT_SCL = 5.1V
BKLT_SDA = 5.1V

LCDBKLT_SW = 0.085V

Can you help?

 

[2informaticos]

Image should appear before backlight.

Do you get 3V3/5V_S0SW_LCD?
DP_INT_HPD should go high at same time.
If not check U8510, pins 2, 3 & 8.
Also check diode mode to ground on EDP_INT_AUX_N/P lines.

 

[hgoncalves]

Hi,

3V3_S0SW_LCD = 0V
5V_S0SW_LCD = 0V DP_INT_HPD = 0V

U8510:
PIN 2 = 0V
PIN 3 = 0V
PIN 8 = 0V

Diode reading:
EDP_INT_AUX_N = 0.005
EDP_INT_AUX_P = 0.225

Is it CPU?

 

[2informaticos]

"EDP_INT_AUX_N = 0.005"
Yeah, CPU's eDP output is damaged.
On this board, there is no series capacitors as protection.

 

[hgoncalves]

TKS!