820-00840 not working from the battery [SOLVED]

Kappy

Member
I have the above which had mild liquid damage around the board which has now been fix and the logicboard is working but my problem is the battery.

It will work with both the power lead and battery connected or just the power lead but if I pull the power lead out with the battery connected it turns off.

In the OS it shows a percentage and say's it charging. If I go to system under power, it says that the battery is connected and charging. If I leave the power lead connected you can see the percentage going up.

At first, after measuring around the board, what seems to be missing are the SMBUS_BATT_SCL, SMBUS_BATT_SDA and SYS_DETECT_L. So I thought it was the SMC, but with the SMC showing the correct information when it's in the system profile then, I've ruled this out for the time being. After more digging around I found that I was missing PP3V3_G3H on the battery alone. and to be more specific PM_EN_P3V3_G3H which comes from U7000. I replaced this, but it made no difference.

So now i'm stuck, I know PM_EN_P3V3_G3H is created by U7000 but there must be something else externally that switches that on.

One last thing I have noticed with just the battery connected PM_EN_P3V3_G3H if fluctuating between 0.3v-0.6v, PPBUS is showing 11.45v

Any pointer in the right direction
 

Kappy

Member
Hi, tried that and no difference. initially after changing R6905 I have 0v on P3V3_G3H.
After connecting the power lead and then removing it with the battery still connected P3V3_G3H dropped to ~1.8v - ~1.7v fluctuating and slowly dropping to now after typing this to ~1.3v - ~1.2v.
 

Kappy

Member
Battery connected
C6990 is 11.51v
R6991 is 0v

Power lead connected then disconnect (battery connected)

C6990 - 11.51v
R6991 - 0.54 - 0.32 fluctuating
 

Kappy

Member
Sorry I forgot to mention that I've replaced the U7000 twice. Not sure it these are reballed cheap Chinese or if they are genuine. Is there any other factors that are needed to enable PM_EN_P3V3_G3H voltage signal to come from the U7000.
 

2informaticos

Administrator
Staff member
Try another battery, even old.
Check voltage and diode mode to ground on SCL/SDA lines of battery bus.
Looks like SMC communicates with battery and U7000, but check values.

Do you have any voltage at R7075 with battery only?
 

Kappy

Member
Tried another battery still the same.

There is no comms on the SCL/SDA lines and I wouldn't have thought there would be as there's no P3V3_G3H so surly the SMC isn't even being powered.

I just don't know if there is any communication between the CD3215 and the U7000 which then turns on the PM_EN_P3V3_G3H which then gives 3.3 volts that then turns on the SMC for comms with the battery. That's what in thinking but I could be wrong.
 

2informaticos

Administrator
Staff member
You don't need power on board to check diode mode to grounbd on signal lines.
And wanted to know the voltage on SCL/SDA lines with charger connected, of course.

U7000 doesn't need to talk with CD3215, nor SMC, to enable 3V3_G3H; valid thing for battery mode only.
In fact, SMC cannot wake up if 3V3_G3H is not generated first.
 

Kappy

Member
R7075 battery only - 11v

voltage with battery and power lead connected taken at SMC

SCL - 3.4v - same at J6951
SDA - 3.4v - same at J6951

Voltage after taking power lead off with battery connected

SCL - 1.9v - fluctuating
SDA - 1.9v - fluctuating

Diode mode reading

SCL - 0.40
SDA - 0.40
 

Kappy

Member
Definitely not U7000 or the SMC, ive just removed both from working board and reball them onto this piece of cr*p and the measurements are the same
 
Last edited:

2informaticos

Administrator
Staff member
I don't know where you measure.
R7075 must have 5V on both sides...
Your values points to bad U7000.
Which is the exact PPBUS_G3H voltage with charger only?
 

2informaticos

Administrator
Staff member
OK, time to make a test.
Remove R6991 and inject 5V (externally) at its pad 1; going to U6990.
Check if then board works on battery alone.
 

Kappy

Member
Yes … both SCL/SDA lines are 3.4v and I've just installed back into the case and using the battery and applying 5v to R6991 i'm able to make it work by pressing the power button.
 

2informaticos

Administrator
Staff member
So, for some reason U7000 doesn't want to enable 3V3_G3H power supply on battery only.
Be sure Q7040/65 are good.
Compare voltages around U7000 in battery mode with a good board.
Also compare diode mode readings.
 

Kappy

Member
Already replaced both Q7040/65...

I don't have any working boards as I've taken the SMC and U7000 from it and the other U7000 decided to play hide and seek :)

So do you think that there is another component that tells the U7000 to switches between power lead and battery? I know on the older models it was automatic but with the U6990 having the enable maybe there's another component involved.

Thanks for your help so far. Please don't give up yet :)
 
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