820-3437 3.42v present but dim green light

[macattack600]

Hi i'm working on a 820-3437

all rails come up correct voltage until I get to 5v rail PP5v 0v

L7095 has 3.42 volts but i'm getting a dim green light ?

I reflowed smc and change U7100 and still no change?

[mon2]

Re: 820-3437 3.42v present but dim green light

Are you using an original power adapter ?

until I get to 5v rail PP5v 0v

There are many such rails on the logic board. Which one exactly ?

Post the voltages for the attached.

[macattack600]

Re: 820-3437 3.42v present but dim green light

Yes I use 85w original on ALL my board repairs.
I go down the list on power aliases for rails and it gives correct voltgage until I get to PP5V_S5 I have 0V but the real issue is no Solid green light .


I Need solid green light first, or orange , i'm confused cause I get 3.42 at L7095 I'm missing PP5V_S4RS3 (5v subrail) but that's because i'm also missing 5v rail , right?

That signal comes from PCH if i'm not mistaken i'm hoping that's not the start of my problem

[reformatt]

Re: 820-3437 3.42v present but dim green light

A more structured troubleshooting approach will reap dividends. You are jumping all over the board.

Are you testing outside the chassis with trackpad etc disconnected (most common cause of missing LDO voltages)? Use a known good DC IN board and LIO cable then check PPBUS_G3H for 8.6V, and PP3V3_S5 for 3.3V. You won't get PP5V_S4RS3 until PM_SLP_S4 goes high, and there are many possible reasons for it to be missing (or pulsing).

[macattack600]

Re: 820-3437 3.42v present but dim green light

I have no 3.3v at the big coil . I thought the main goal was was to get a steady green or orange light before I troubleshoot? PPBUS_G3H is infact 8.6v
I brought up that signal PP5V_S4RS3 cause it was posted with diagram by Mon2

I have multiple good known DC In LIO Cables i've tested in and out of case including trying to bypass smc in debug mode .

[reformatt]

Re: 820-3437 3.42v present but dim green light

A board should still run off the Magsafe regardless of the onewire circuit. It won't charge, but it should at least power on. So no, it's a roadsign but not something to tackle straight up.

If you are missing your PP3V3_S5, this is where you start from. Check you have SMC_PM_G2_EN high. If this is good, then troubleshoot U7501 (short to ground etc). If not, go back to SMC and check around that area. Since you have PPBUS_G3H at 8.6V, this indicates the SMC isn't in reset and it's communcating to U7100.

[mcplslg123]

Re: 820-3437 3.42v present but dim green light

What about ADAPTER_SENSE??

[Adenitz]

Re: 820-3437 3.42v present but dim green light

Please, just write voltages that mon2 suggested:
Something like:
1: (PP5V_S4RS3)
2: (PPDCIN_G3H)
3: (PPDCIN_G3H_ISOL)
...

[macattack600]

Re: 820-3437 3.42v present but dim green light

SMC_PM_G2_EN was not present at all.

I inspected SMC and saw light corrosion under pin 82 SMC_XTAL.
Removing BGA it was infact corroded on 4 points and it pulled pad #82 because of corrosion. Luckily I can run wire since i'm on the edge of the chip .
I will reball another SMC and run wire and report back.

[macattack600]

Re: 820-3437 3.42v present but dim green light

I Reballed SMC and the board is fully working, I got lucky I scraped the pad and did not have to run wire.
Thank you everyone and reformatt especially for the detailed pointers. Cheers!