macbook air no backlight 820-00165, help please, bad gpu or fixable?

[imcool]

BKL_PWM AND EDP_BKLT_PWM are 0.35V ❌ ❌ (which is not good?)
R7704 AND C7704 are not shorted out to ground.

BKL_EN is +3V ✅ 🆗
VIN is +5V ✅ 🆗
PPVOUT_SW_LCDBKLT_FB +8V ✅ 🆗
SMC_LID is present +3V ✅ 🆗

i put SMC_LID volts to BKL_PWM and still no backlight. I jumped wire from SMC_LID TO BKL_PWM and still no backlight
Please help, is it LCD or GPU U0500 ?




Schematic and board view files are here
https://www.badcaps.net/forum/showthread.php?p=709704

[adiserwis]

Re: macbook air no backlight 820-00165, help please, bad gpu or fixable?

Looks like the screen or the LED driver (U7701) gone bad, any signs of liquid damage, you may want to check if screen connector is clean and no cracks in soldering, sometimes it's all it takes - clean and re-solder connector

[imcool]

Re: macbook air no backlight 820-00165, help please, bad gpu or fixable?

Looks like the screen or the LED driver (U7701) gone bad, any signs of liquid damage, you may want to check if screen connector is clean and no cracks in soldering, sometimes it's all it takes - clean and re-solder connector

but BKL_PWM AND EDP_BKLT_PWM are 0.35V ❌ ❌ is missing already and how come when i put SMC_LID volts to BKL_PWM and there was still no backlight.

You think its U7701?

[mcplslg123]

Re: macbook air no backlight 820-00165, help please, bad gpu or fixable?

U7701 IS Doubtfull. Try a mild reflow of this IC with lot of flux.

[imcool]

Re: macbook air no backlight 820-00165, help please, bad gpu or fixable?

U7701 IS Doubtfull. Try a mild reflow of this IC with lot of flux.

ok, thank you i will try that,

so BKL_PWM AND EDP_BKLT_PWM are 0.5 VDC can be caused by bad u7701?

[imcool]

Re: macbook air no backlight 820-00165, help please, bad gpu or fixable?

bump

[Siddig]

Re: macbook air no backlight 820-00165, help please, bad gpu or fixable?

Chang U7701 Ic.

[mustafa4444]

Re: macbook air no backlight 820-00165, help please, bad gpu or fixable?

EDP_BKLT_PWM is 0v in air 1466. PPVIN_S0SW_LCDBKLT is also 0v. No input to backlit ic. No shorting near U7701. Slightly reflod the PCH section of CPU. Reprogramed Bios. Still dim display. Any help ?

[dellxps15]

Re: macbook air no backlight 820-00165, help please, bad gpu or fixable?

if u put a light onscreen can u see the image ?