A1706 Touch Bar No LCD power (not flexgate)

[Stephen]

Pretty simple. I have no power on EDP_PANEL_PWR_EN

Replaced with new chips and board now finally turns on (u8510) LCD is known working so it is not the LCD. Replaced the LVDS as well and its known good. There is no voltage at R8590 and R8591 (NO STUFF RESISTOR)
I am certain this is the cause, because this area had power before and now it does not. LCD PIN 43 on LVDS PPVOUT LCDBKL has power (12 Volts)

Hooked up to HDMI and displays on HDMI. Board powers on etc. Did test multiple LCD that are cracked but have good backlights to no avail. Any suggestions?

[mon2]

Re: A1706 Touch Bar No LCD power (not flexgate)

See comments here from @Piernov:

https://www.badcaps.net/forum/showthread.php?t=84035

[Stephen]

Re: A1706 Touch Bar No LCD power (not flexgate)

After further testing U8501 and U8500 have no power in certain points when removed. I see this is the LCD PWR area but I am still lost. Maybe bad DIODES?

[mon2]

Re: A1706 Touch Bar No LCD power (not flexgate)

Can you post your logic board # ?

[Stephen]

Re: A1706 Touch Bar No LCD power (not flexgate)

A1706 820-00239

[mon2]

Re: A1706 Touch Bar No LCD power (not flexgate)

Voltage readings for the following ?

1) PP5V_S0

2) LCD_PWR_SLEW

3) PP5V_S0SW_LCD

4) PANEL_P3V3_EN

5) LCD_PWR_SLEW_3V3

6) PP3V3_S0SW_LCD_R

7) PP3V3_S5

8) EDP_PANEL_PWR_EN and also BUF_EDP_PANEL_PWR_EN

9) PP3V3_S0SW_LCD

Above are all from sheet 80/119.

[mon2]

Re: A1706 Touch Bar No LCD power (not flexgate)

Also, post the voltage reading for:

PPVCC_S0_CPU

Is it stable or does it fluctuate ?

[Stephen]

Re: A1706 Touch Bar No LCD power (not flexgate)

Will get back to you about this later tomorrow!

[mon2]

Re: A1706 Touch Bar No LCD power (not flexgate)

Stephen, did you ever post the above requested value? It was to repair another logic board.

[Stephen]

Re: A1706 Touch Bar No LCD power (not flexgate)

I did not lol. I actually repaired that board. It was a bad diode. I have another post with a different board VERY odd with the LCD turning on and only being black with the back light on. You got any suggestions?