820-00138 Not Charging

[hambook]

I have an 820-00138 on the bench that isn't charging the battery, but runs fine from the battery. No liquid damage, was dropped on its side and hasn't charged since then. Tried a known working DC board but same result. I tested with an el cheapo charger and it does charge, just not with my bench psu. U7000 has continuity to the Magsafe and voltages seem good (1 - 3.45v 4 - 3.42v 5 - 3.42v). Given that it charges fine with the shitty charger, is this a leakage issue like some of the previous forum threads? If so, how do I test to find the culprit?

 

[2informaticos]

Did you test with 85W charger for sure?
Machine works good with charger alone (no battery)?
Magsafe light stays amber?

 

[hambook]

It's a genuine 85w charger. Machine runs without batt and light stays amber. Tried a brand new battery to rule that out too and the new battery wouldn't charge either.

 

[2informaticos]

What's the exact PPBUS_G3H voltage, w/ and w/o battery connected?
Check SMC_CHGR_BMON/DCIN_ISENSE levels, with battery connected (page 45).

 

[hambook]

PPBUS_G3H with the battery is 12.5v when powered off, but it falls to 10.8v when I power on the machine. On charger without battery it's steady 12.5v. SMC_CHGR_BMON is 0.049v and DCIN_ISENSE is 1.05v

 

[2informaticos]

1V at SMC_DCIN_ISENSE means a lot of current consumed from charger.
Is that value in off state with battery connected?
Post exact resistance between pins 27/28 of U7100.

 

[hambook]

With battery DCIN_ISENSE is 1.05v and without it is 0.24v. Resistance between pins 27/28 of U7100 is 20.9 ohms

 

[2informaticos]

1.05V in off state???

 

[hambook]

Correct, both of those measurements were taken while the board is plugged in to power but turned off.

 

[2informaticos]

Then is strange; SMC_CHGR_BMON_ISENSE should increase too.
1V at SMC_DCIN_ISENSE denotes approx 2.5A through R7020.
If board is off, almost all current should go through R7050.
In such case, SMC_CHGR_BMON_ISENSE should be approx 0.45V; you've reported less than 0.05V there.

0.24V at SMC_DCIN_ISENSE is also too much for off state without battery.
It suppose approx 0.6A consumption.
You may need to change U7100.
Post its voltages; 1, 2, 3, 9, 12, 13, 14, 15, 17, 19, 20, 25, 27.

 

[hambook]

Went to go take measurements and the first few were 0v and I noticed I lost my green light and PSU now pulls 0 amps. Did some checking and I seem to be missing SMC_BC_ACOK at U7001, but I still have PP3V42 going in. Is that a good sign U7100 is pooched?

 

[2informaticos]

So you cannot measure above mentioned pins without Magsafe light???

 

[hambook]

Apologies, forgot to paste my results
1 - 17.15v
2- 18.08v
3 - 0.762v
9 - 0.030
12 - 3.4v
13 - 3.4v
14 - 0v
15 - 0.046v
17 - 0.262v
19 - 5.502v
20 - 5.507v
25 - 5.190v
27 - 0.005v

 

[2informaticos]

"3 - 0.762v"
Bad value!
Check R7110, possibly open/corroded.
Also remove C7111 and check again.

 

[hambook]

Just to check my understanding (hopefully I'm learning lol) pin 3 receives its power from PPDCIN_G3H_ISOL which is what also powers U7090 through D7005. So that should be the same voltage as my power supply is outputting then, not next to nothing?

 

[2informaticos]

Yeah, R7110/11 divisor creates ACIN signal for U7100.

 

[hambook]

R7110/11 looked like they had some gunk around them, so I replaced both from a donor - same voltage as before. Removed C7111, voltage dropped to 0.006v.

 

[2informaticos]

Do you have correct voltage at pin 1 of R7110?
If you've changed the resistors with correct values, then change U7100 and check again the voltage.

 

[hambook]

Did have correct voltage at R7110 pin 1, double checked the values of resistors. I went ahead and replaced U7100, got green light back. When booted board still does not charge though. Here are my U7100 voltages now:

1 - 0.004v
2- 17.90v
3 - 4.32v
9 - 0.293v
12 - 3.4v
13 - 3.4v
14 - 3.305v
15 - 0.080v
17 - 12.58v
19 - 5.513v
20 - 5.522v
25 - 17.50v
27 - 18.33v

 

[2informaticos]

Post PPBUS_G3H voltage with both charger and battery connected.
12.58V is good without battery.
Also post resistance between pins 17/18 of U7100.