820-00165 - No power (usually) no light on charger. SOmetimes green light.

[grmacs]

I was able to identify that SMC RESET L stays low even without u5110 pin 5 stays low. I do have 3.42V on pin 1 of R5100. R5100 is at 76ohms.

Reflow SMC? Anything else to check first?

 

[2informaticos]

"R5100 is at 76ohms"
What this mean?
It is 100K resistor.

Do you mean 076 diode mode (or 76 ohm) to ground at pin 2???
In such case, clean first J6100 and check again; you may need to remove it.
If still the same, remove R7100.
Last option, replace SMC; you can try a reflow first...

 

[grmacs]

Sorry that was a typo, r5100 is at 26k ohm not 76ohm (I'm almost certain it was at 76k ohm prior which is what i was previously trying to report. 3.43V on pin 1 of r5100 and .446V on pin 2.

 

[2informaticos]

Then check all I said before...

 

[grmacs]

oh ok. Definitely will do. thanks

 

[grmacs]

you're a goddamn genius. not sure how there was still anything around that area of the board but cleaning around j6100 got lights working on charger and fan spin.

 

[grmacs]

No Backlight on this. Replaced LED driver 8550.

Ran trace XW7720 as there from a5 to tp pad per Louis video as there was no connection there.

Here are voltages I've checked:


EDP_BKLT_EN: 3.3V

LCDBKLT_EN_L: 0V

LCDBKLT_EN_DIV_L: 2.8V


8.5V on LCDBKLT_BOOST, PPHV_S0SW_LCDBKLT


Resistors for LED_RETURN1,2,3,4,5,6 are all reading 0hms and connected to LCD

BKL_PWM 1.48V
BKL_EN 2.82V

I have display just no backlight. DId PRAM Reset for 3 chimes. Nada

Suggestion??

 

[2informaticos]

Remove R7704 and run a wire from C7704 to R7715.
If get backlight, do PRAM reset again and rebuild the circuit.
Let us know the result.

 

[grmacs]

assuming wire from pin1 r7715 to pin 1 c7704... essentially sending BKL_EN to BKL_PWM?

 

[2informaticos]

Exactly, check if get backlight then...

 

[grmacs]

no backlight w jumper from c7704 to r7715

 

[2informaticos]

Do you have 3V at BKL_EN/PWM now?
2.8V is good too.

Did you try known good LCD assembly?
Post diode mode to ground at all return resistors.

 

[grmacs]

I had to rerun the jumper for pad a5 again after it shorted and blew my LP8550 lol... BUT it's up and running! Couldn't have done it without you. Thanks for your help its very appreciated!

 

[2informaticos]

Did you rebuild BKL_PWM circuit?

 

[grmacs]

Indeed. And after I replaced the blown fuse from shorting out the a5 wire everything worked

 

[grmacs]

I don’t think my trace wire was done well enough first time so it shorted and I redid trace, lp8550 and then fuse