820-2838 Missing LCD_BKLT_EN & BKLT_PLT_RST_L

[2informaticos]

BKLT_EN comes from MCP too, as PCI_RESET_L.
Definetely MCP issue then.
Both signals have weak pull-up inside MCP.
Short pins 3/4 of Q9807 (or leave R9810 out of board) and check if backlight goes off when close the lid.

 

[Kittu]

Removed R9810 to restore BKLT_EN and Replaced R1600 with 200K to maintain 3.2V. Subsequently,
1. System booted with SSD
2. Both USB ports worked
3. Backlight sustains at full brightness and PPVOUT_SW_LCDBKLT measures 24V

As you rightly say, it seems to be a busted driver inside each of the two signals within MCP resulting in weak signal which is hampered by the pull-down resistors.

Seems MCP survives for now!

Thank you so much for your guidance. Presume we can consider this post closed and issues resolved, albeit with a twist in the tale and new ways of reviving dead backlight signals from the MCP!

Cheers!