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No backlight 820-00165
- Thread starter Neil250
- Start date
Try 2-3 times PRAM reset.
Also try starting in SMC bypass mode.
Did you try known good LCD assembly?
Also see what happens if tie together pins3/4 of Q7707.
Also try starting in SMC bypass mode.
Did you try known good LCD assembly?
Also see what happens if tie together pins3/4 of Q7707.
"Tied together pins3/4 of Q7707 ---> still no backlight"
Do you get voltage at L7701 then?
Do you get voltage at L7701 then?
Keep the pins tied together.
Inspect XW7720 integrity.
Post diode mode around U7701; especially at return resistors and D7701 pins.
Inspect XW7720 integrity.
Post diode mode around U7701; especially at return resistors and D7701 pins.
XW7720, I have never worked on this switch trace before. I don't know what I am looking for in terms of integrity.
D7701
Diode to ground
1: 0.45V
2: 0.65V
R7717-R7722: 0.64 V Diode mode to ground on all pins
I saw this image: do I just scrape at the circular area and run a wire as below:
So I scraped away the area and bridged with solder.There is continuity with the diode.
Last edited:
Do PRAM reset 2-3 times.
Post BKL_EN/PWM.
Post BKL_EN/PWM.
Yes...
Remove R7704 and tie together BKL_EN/PWM.
EDP_BKLT_PWM comes from PCH.
Forcing BKL_PWM to 3V can help in diagnose process.
Forcing BKL_PWM to 3V can help in diagnose process.
"Did you try known good LCD assembly?"
???
Change U7701.
Once removed, check continuity from A5 ball (FB) to K/D7701.
???
Change U7701.
Once removed, check continuity from A5 ball (FB) to K/D7701.
Yes, rebuild original traces.