820-2936 no backlight

[Modder1]

.5477 pin 5 q9707 diode mode
resistance to gnd pin 5 9707 99.3kohm
pin 5 9707 3.34
c9020 12.18

I also made sure that everywhere I could find PPBUS_G3H is 12.24. I had to run a jumper from backlight fuse f9700 to pin 4 on q4262 to get that up
changed a bunch of stuff I saw that was corroded
changed lp8550 chip
tried different lcd and connector
reflowed the lcd connector
I am just not sure, should I give up on this one?

 

[dukefawks]

Voltage on R9715 and R9704?
The 12.24V on PPBUS is also worrying because that means SMC is not talking to the ISL6259. You measured 12.5V on F9700 before so I wonder what happened there.

 

[Modder1]

0V Pin 2 R9715
0.14V both pin 1 and 2 R9704

 

[2informaticos]

Do you get voltage at pin1 of R9731?
If not, R0910 is bad.
Check again exact voltage at F9700 too...
PWM missing from PCH, but there is a trick you can do to test backlight.

 

[Modder1]

I replaced R0910 and noticed R9704 smoking, so I changed R9716, C9704, R9704,R9714 and R9731 and I am still seeing smoke from R904. this happen only when plugged in, with battery only it does not bubble and smoke
now I am nervous to put more power to take measurement of F9700

 

[dukefawks]

This is 3 months ago, I'm sorry but I'm not digging through this whole topic again.

 

[larossmann]

I replaced R0910 and noticed R9704 smoking, so I changed R9716, C9704, R9704,R9714 and R9731 and I am still seeing smoke from R904. this happen only when plugged in, with battery only it does not bubble and smoke
now I am nervous to put more power to take measurement of F9700

A component smokes when more power is going through it than it is rated for by a significant amount. The only logical way for R9704 to smoke is if it is shorted to ground. The only way for it to short to ground is via U9701 or C9704. I would measure resistance to ground on both sides of R9704(NO POWER APPLIED DURING RESISTANCE MEASUREMENTS!). This is most likely you fucked up soldering something, or U9701 is bad. You didn't mention replacing U9701 after the smoking.

 

[dukefawks]

If R9704 is really smoking something is VERY fucked. No way U9701 or U1800 can provide enough current to do so without them fucking up. So by now U1800 and U9701 are dead I'm sure.