[SOLVED]820-3437-B - no green light. PPBUS_G3H missing

[Atomrepair]

Water damage.

I first got 0.48 volt on PPDCIN_G3H.
I've replaced (from donor board):

Q7010
U7090
Q7180

replacing the first two wasn't necessary, but after replacing Q7180, PPDCIN_G3H is 18V.

CHGR_AGATE is 0V with U7100 present. I lifted U7100, CHGR_AGATE went to ~16V.
After placing a (new) U7100, it went back down to 0V.
Resistance from CHGR_AGATE to ground is 845KOhm

PPDCIN_G3H_INRUSH is 0V

measured 9 Ohms on pin 1 of R7180. Seems a bit low, but I dont understand the Inrush circuitry. Some type of protection?

 

[Atomrepair]

Update: found shorted caps in the PPDC_G3H_INRUSH circuit (C7130, C7131, C7135 and C7136). Not sure if all shorted, but replaced. Short to ground on this rail is now gone,but voltage on this rail and on PPBUS_G3H is only 1V.

edit: Replaced Q7130 just to be sure, but no change.

 

[dukefawks]

The original defect was probably only those caps. The problem now is probably in the other stuff you did. Also power up without U7100 is pretty unsafe and can kill FETs.

Check Voltage on pin 2 of U7100 and check resistance between pins 17/18 27/28. Green then orange light present?

 

[Atomrepair]

What FETS would be at risk if powering on without U7100? Q7130? If so, can you explain why? I assumed that with the gate signal from U7100 missing, nothing bad could happen.

U7100 Pin 2 = 16.1 V
resistance between 17/18 = infinite
27/28 = 20Ohm

R7151 is ~4 Ohm
R7152 is 0.L
R7150 has a large crack at pin 1

No light on charger

 

[dukefawks]

17/18 should have 2-3Ohm so there is a problem there. Shouldn't affect the green light though. Fix the R7150/51/52 issue so that pin 17/18 measures 2-3 Ohm again. Also check ACOK. These boards will power on without a green light so if PPBUS comes up at 12.6V again then we can look at the green light issue.

 

[Atomrepair]

I've replaced R7150, R7151 and R7152. Resistance on pin 17/18 is now 3.1 Ohm.


I've replaced Q7180 again, as I wasn't sure of my earlier replacement there. After that, I got 8.6V on PPBUS_G3H.

I replaced the slew of components I took out of the battery circuit, the LVDS connector, C8317, F7700 and Q7706 (all were shorted, broken and/or disfunctional).

Laptop is now powering on when I plug it in, and screen is working.

Remaining problems:
- Power button wont work
- Laptop will turn on, but reboots twice while doing so. When it does get to the OS or ASD, it often reboots after a while anyway.
- Battery not detected (battery could be bad, I dont have a known good one yet)
- Charger light starts green, then goes orange (with or without battery inserted).

Managed to run ASD EFI once, with default options except ram. It throws a few sensor errors (Th1H, TB0T, TB1T, TB2T) but everything else passes.
ASD OS - laptop started rebooting itself when about 75% through the tests. Didnt see the errors.

PPBUS_G3H is now sitting at 8.2V. Board behaves the same as above, but keyboard& trackpad wont work when plugged in. The 8.2V stays.

Couple of measurements:

PP3V42_G3H 3,42V
PP3V3_S5 3,33V
PP5V_S5 5,12V
PPVRTC_G3H 3,4V
PM_DSW_PWRGD 3,4V
SMC_RESET_L 3,4V

 

[dukefawks]

Power button issue could also cause the shutting down. Could be bad keyboard or the trackpad/flex cable/connector.
Turning on/off 3 times before boot is normal.
PPBUS is at 8.6V so battery data bus is probably ok. Looks like a dead battery to me.
Charger light going green then orange even without battery is normal.

8.2V on PPBUS means no communication from SMC. Could be crap under SMC/dead SMC or crap under battery connector. I assume this is without battery connected.

TBxT are all battery sensors, th1h I think is on the IO board on these airs, LIO finstack sensor. Bad IO board/cable/connector or crap under SMC.

 

[Atomrepair]

SMBUS_SMC_5_G3_SDA is 3 Ohms to ground, problem was in U7100, which was fine before I hooked that battery up.
I've replaced U7100 again, which fixed the short. Both pin 5 and 6 of the battery connector are ~80k now, same as the donor boards I have.
However, PPBUS_G3H remains at 8.2V. Could hooking up the battery from this laptop have damaged the SMC? The battery connector looks clean now (after a short UC session), but I neglected to check before plugging the battery in.

If SMC is the prime suspect I'll have to order a stencil for my BGA jig and wait for that. to arrive.

I've added a few pics, might help. I'm ashamed of the way the new soldered in LVDS connector looks, but I'm holding off on adding a new one until the board is functioning properly..

 

[dukefawks]

The SMC was probably killed. Yes a faulty battery can kill the SMC/ISL6259 if the 8V battery voltage shorts out to the data pins. So this battery may be a killer.

It also has quite severe corrosion. The trackpad flex cable/connector will certainly be a problem too.....

 

[Atomrepair]

Is there a way to check whether the battery is indeed the cause of this without hooking it up? Maybe by attaching it to my lab supply and measuring data lines?

 

[dukefawks]

For the $40 I would just not risk it. Replacing another SMC is a lot more work....

 

[Atomrepair]

I'm looking at getting SMC reballing stuff and have ordered a set of new batteries. Thanks so far Duke, I will report back later.

 

[Atomrepair]

Finally received my SMC jig last week, I got around to taking one off a donor board and reballing that. First time doing this sucked, but I got it on the board in the end. PPBUS is now back to 8.6. Machine runs off new battery and charges it as well.
I also found a short to ground on the trackpad/keyboard conn at pin 18, SMC_LSOC_RST_L, sadly not before trying to run the laptop with that shit connected. Everything still working, so it's hopefully still be ok.
Going to order me a trackpad and flex to see if that fixes the remaining problems. Probably not, I expect the keyboard will be messed up too but we'll see.

 

[jadao]

Does the short to ground remains on pin 18 when no cable is plugged in?
If so, you have c4836 and u5110 suspected to give SMC_LSOC_RST_L a path to ground.
Otherwise, check trackpad/keyboard, I doubt connector problem because there is no adjacent ground pins next to pin 18.

 

[Atomrepair]

jadao SMC_LSOC_RST_L is fine on the logic board itself (with nothing connected). I might have worded my last post a little unclearly. The short to ground is located on the trackpad pcb. I don't think I'll bother trying to fix that thing.

 

[Atomrepair]

After replacing the trackpad and flex cable, keyboard and trackpad are now working fine.
This board now passes all ASD tests apart from one: Fan Motor exhaust test 4.

ASD EFI error is:Motor is spinning slower than it should
ASD OS: Motor unable to stabilize between min and max limits

PP5V_S0 at fan connector is at 5.1V.
PP3V3_S0_FAN is at 3.3V

Fan actually seems to run fine. It's running silently when laptop isn't stressed, loudly when it is.

Seeing that I've replaced the SMC on this board, and that one of the inputs of Q6060 (which looks fine) comes from the SMC (SMC_FAN_0_CTL).. I think I know what the likely culprit is going to be, but I'd really hate pulling an SMC off an otherwise (finally) fully functional board at the risk of making it worse than it is now. Anything else I might do before messing with the SMC again? I've half a mind to run the thing through some serious stress testing to see whether an issue crops up.

 

[jadao]

Before reflowing/relacing SMC: I see in your post that before relacing smc you ran ASD but it only reach about 75% of the test.
Can you check if you might had this error before smc replacement? I don't remember when motor fan is done in asd sequence tests.

Do you have a spare fan to test?

Make sure resistors R6065 R6060 R6061 measure good an no sign of water corrosion

 

[Atomrepair]

I've hooked everything up, assembled the machine fully and ran the tests again. Its passing the fan exhaust (and all other tests) in both EFI and OS versions of ASD.
Not sure if intermittent issue or if something need to be connected for the fan to work, other than the fan itself

 

[Atomrepair]

I've run ASD EFI and OS several times now (all default tests) and it's passing everything every time. I've booted up OS X and ran furmark (or whatever its called nowadays) for a couple hours without issues.

Anything else I ought to do before calling this damn thing fixed?

 

[Atomrepair]

This has been back at the customer for a while now and still running fine. Mark as solved please