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PM_BATLOW_L 3.26v PM_PWRBTN_L 3.35v PM_RSMRST_L 2.98v PM_DSW_PWRGD 3.35v PCH_DSWVRMEN 2.46v "Trigger SMC_ONOFF_L" never did this, can you explain? Sorry for lack of knowledge. I have to short SMC_ONOFF_L to ground and measure voltage drop on PM_PWRBTN?

Amber light - yes G3H - 8.49v 3V42_G3H - 3.38v 3V3_S5 3.29v Steady 3V3_SUS - 3.29v Steady Looks like prior liquid damage was around backlight and some caps on 3v42_G3H

820-3437-b Board came with prior liquid damage few months ago, fixed at the time. Customer came few days ago with not booting macbook air, i checked and noticed that there is no 5V S3 and 5v S0 also. 5v S5 present. Was poking around and applied heat to SMC around 200c for diagnostic purpose...

Solved! Bad J4810 on MBL, replaced, working fine now. Thanks for your input.

when board is on, i am getting 3.3v on PP3V3_S4 on the J4810, when i check on the keyboard side same line it is 1.62v, should it be like this? it does not give me a short, diode mode read is 0.434v, when flex is out there is continuity between pins, when flex is in there is no continuity but...

i have tried MBL in new assembly, exactly same behavior. TP works fine in both of them. What will cause fan to stop after chime?

when machines is powered on(open lid), 5V_S0 present everywhere, also Pin 1/19/20 of J4810, fan still not spinning. Last time i was checking with closed lid. I noticed if i hold multimeter on pin 1 for like 1-2 minutes, 5V_S0 vill go to 2v-1v-4v-0v and then again to 5v in that time at least once...

I have only PP3V3_G3H_KBD present on J4810 after chime, nothing else. Before chime all present. Fan stops spinning after chime.

yes, i understand that. In PDF that is called PP5V_S0_KBD, in boardview just PP5V_S0. Pin 19/20 on J4810. What could be cause of its disappearing from J4810?

Got 00840-a here, came originally with jam filled keyboard, got new assembly, some (jam) marks around wifi, cleaned, reflowed. Everything works except keyboard. Boots up, trackpad fine, wifi, sound etc. Checked PP5V_S0, i am getting 5v there till i hear the dong(chime) from speakers and then fan...

i hardwired J9500 4 HDA lines to LIO board to rule out bad connection for sure, did not worked. So it will be no fix. Thanks for your input anyway.

i have tried 3 different Flex/LIO boards. Replaced J9500 All HDA Pins reads ok, diode mode close to working board. all i have left is to "just in case" replace all resistors on HDA lines and if thats not working thats mean its CPU? Or hardwire 4 HDA lines from J9500 to Flex?

i found one more 3437-b. HDA_RST_L is 1.49v with LIO Connected with flex. without flex HDA_RST_L is 0v on working board.

customer collected yesterday 3437-b. Will have to find board to check, will let you know.

HDA_RST_L is 0v out of the chassis when fan spins at max.

Hi Kappy! I was afraid that it might be cpu itself as there is no more things to check.

I changed J9500, no luck. i cannot measure HDA_RST_L when board is inside the housing, but when it is out it is 0v. R1310 33ohm R1311 33ohm R1312 33ohm R1313 33ohm Noticed that outside the housing fan spins at max rpm, with one I/O board it is gradually starting to increase speed till maxes...

originally, corrosion was around u7701, u5000 and u7100. I cleaned it all, is there something around SMC that is sound related, that i could have missed?

any ideas?

Check if caps/resistors exist on these lines. I checked all components and lines, all intact. HDA_SDOUT R1313 33ohm HDA_SDOUT_R R1921 1kohm HDA_SYNC R1311 33ohm HDA_BIT_CLK R1310 33ohm J9500 diode mode readings: Not working sound board:00165-a Pin47 0.465 Pin45 0.460 Pin43 0.413 Pin39 0.464...