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Well making some progress anyway. Now it goes to 19.9V and up to eventually climbs to 1.8A and 36W but no chime no data activity. USB drive has solid light for a while and shuts off. Trackpad activity present. Still not registering DFU but seems like trackpad activity never goes away even after...

Thanks for help with that. NOt sure if I'd have figured out how to isolate that one. it actually is on the PMIC so looks like one I placed from other board had an issue as it at least doesn't appear that it was due to shorted balls and internal to chip (chcking it pin 10 is 0 ohms to pin 9) oye...

I get pulses at the slps2r. Discovered full short on P0v9SLPDDR. zero ohms resistance to ground. Guessing this means I have a dead T2? damnit I've wasted a lot of time on this board.

Board on the bench. I found a short on PP3v3_G3H at C7809 and PMIC U7800. Replaced both. then discovered only one of the CD3215's had the 1.1V LDO when charger connected to it's corresponding port. Replaced U3100 and now get all of the LDO's with charger connected to corresponding port. I was...

I'm wondering if whatever issue this has/had could be breaking the KB backlights I"m testing? Just wondering if the amperage couldve been high at some point. I connected an LED after wondering this and I do see life in that but it comes on just briefly and then goes out til I reconnect it.

Yes. This actually had two issues when I received it, Cracked LCD and no KB backlight so the problem has persisted after swapping to another screen

Not understanding why the hell this kB backlight won't come on. tested connections. from J4915 to U7701 and components in between. replaced all of the Caps C7723/4/5/6/7. Is there a good way to just have the kB backlight stay on? I guess I could try replacing U7701 again... I'm at a loss as to...

Just tried that. No change. I checked diode readings on J4915 and U7701 also. I really don't understand what is preventing the KB backlight from working... Where does the ALS actually control the KB backlight at? I'm thinking the issue must be where those two things tie together?

YEs still 5V. R7741 is reading good. Changed L7720. Still no kb backlight with jumper or with R7747 back in place and jumper removed.

Yeah I checked those and the ISL resistances there checked out. Investigated ISENSE and VSENSE components around the SMC during SMC bypass and couldnt find anything. Reflowed SMC with pressure and board now starts and boots after cool off.

SMC bypass allows the board to boot.

I"m an idiot I don't know why I didn't follow same startup sequence as the A1502/1466/1398 boards. 0V at C1802/3 and realized I was missing PPVRTC_G3H near there but it was present on U2600 the pass through line was damaged next to C2233 so jumpered and now I'm getting a short fan spin and stopping.

I verified both P5v3v3_REG_EN & 5v3v3_REG_EN are present if that is what you mean so I apparently didn't get an accurate measurement previously or it may have restored after some work on the board. PP3v3_SUS is present

I had typed it correctly. Previously had 0V when checking... maybe didnt have good contacts. What is needed to enable P5v_S3... pin 2 of Q7221 should be low, correct? it is 3.4V. PM_SLP_S4_L is not present which I believe is needed to get P5v_S3?

Everything else works. LCD backlight responds to light/dark on webcam so ALS is working. I have 5V both sides of D7720 / L7220. 5V at J4915. Tested FB lines for continuity back to resistors near U7701. Those resistors are zero ohms. R7747 measures ok. Tried forcing 3V to C7747 with R7747...

U7941 1- 3.4V 2 - 3.4V 3 - 3.3V 4 - 0V 5-0V 6 3.3V 7-0 8-3.3V

Diode readings around U7200 look good but tried replacing it. PPBUS G3H is 12.65V. S5 PGood is 3V, SMC PM G2 EN is present. NO 5v 3v3 REG EN. Did a check with FLIR just in case and that isn't picking up anything hot. Multiple liquid contact areas but not seeing anything with serious corrosion...

Reball didn't change anything... I'm at least pretty sure that the problem lies with U7700. Does anyone know if these chips are serialized or do you think it's possible I could pull this from another board and it would work? I don't have a donor board to pull from at this time or I would just...

Found a bad shorted cap under U7700. Fixed and PPBUS_AON is stable but CD3217's are still acting the same so it appears U7700 is affected. I would guess there was liquid contact there. Heating with flux gets the board to start trying to take amps but just cycles. Do you have any knowledge of the...

Yes but unstable... 11.75V-12.35V