820-00164 No Charging/Run off battery/start off battery.

[JohnB8812]

So this one was a refurbished board from some other company and they replaced A LOT of stuff at least 30 components or so. Rework near DC in, PP3v42 area, BKLT area, bottom right back corner of the board, PP3v3_SUS circuit, and a few other areas. Nothing near ISL or SMC. The problem with this one is it will not charge/run off of a battery. It does for sure recognize a good battery; however, the OS shows it as not charging. The board will also not start off the battery by shorting the power pads. PPBUS is 8.56 volts. Here's what I've replaced so far:

The ISL and every single resistor/cap by it. (Current sensing measures good for both pins 17/18 and 27/28)
The ISL along with Q7180, Q7130, and Q7155 at the same time. (Still no change)
The PP3v42 area along with R7005/6 and the diode (didn't trust them still no change)

I am totally out of ideas on what else could be causing this. Any ideas?

 

[2informaticos]

If OSX recognizes percentage, battery I2C bus should be good.
Are you using original Magsafe 2 charger?
Do you get amber light?
Did you try known good working LIO board/flex?

 

[JohnB8812]

For sure known good 85 Watt OEM Mag2
Yes goes green to orange no problem.
And yes using known good mag board and cable not using customers to rule that out

 

[2informaticos]

I supposed you did that, but waited to confirm.
Sometime I forget basic steps and wake up after wasting lot of time...

You probably need to change SMC, to discard it...

 

[JohnB8812]

Ok so def think SMC issue? It would be strange being it's seeing the battery, but I guess wouldn't hurt to try

 

[2informaticos]

Check first SMC_BMON_ISENSE output level.

 

[JohnB8812]

Ok so SMC_BMON_ISENSE is 0.08 volts. I did notice corrosion by U5600. Replaced no change. Have 3v3_S0 into the chip and 8.6 at both CSO pins but nothing on output. No short on output or SMC_BMON_ISENSE. Is it safe to assume the SMC is pulling it down?

 

[2informaticos]

BMON will increase if battery sink current.
It stays low because battery is not charging.
I wanted to see if has higher level there; but looks normal.

 

[JohnB8812]

Hmm ok. So SMC likely ok or worth just replacing to see?

 

[2informaticos]

You cannot discard it 100% unless change it...
Did you try known good working battery?

 

[JohnB8812]

Ok sounds good I will try another one to be sure. For sure known good battery not using customer's to eliminate that variable.

 

[JohnB8812]

Tried new SMC same thing

 

[2informaticos]

Check with o-scope I2C battery bus.
Maybe corrosion under battery connector...

 

[JohnB8812]

I may just replace the battery connector to make sure. Don't have a scope so can't test the bus unfortunately.

 

[2informaticos]

Check any BMON occurrence in the schematic; as SMC_BMON_COMP_ALERT_L, for example...

 

[JohnB8812]

Ok so if they're high that could be bad? Just making sure want to fully understand what each means

 

[2informaticos]

You must interpret what means each signal, following its name.
Then will know if the value is correct, or not.

 

[JohnB8812]

Not sure if normal or not, but SMC BMON COMP ALERT L is 3.3 volts. CPUBMONSNS_ALERT_L is also 3.3 volts. All other BMON lines appear to be zero that come from the sMC

 

[2informaticos]

ALERT_L should be high as correct.
Low level will mean alert triggered.

Do you have good traces from Q7155 to U7100?
3V42 present on battery only?
Which is the value for PPBUS_G3H on battery, without charger?

 

[JohnB8812]

I will check the traces on those two. No voltage is present anywhere off the battery alone. With just the charger, PPBUS is for sure 8.56 volts with old and new SMC.