NM-C861 BQ24780S charging issue

[rookieme]

Hello,
The system was able to power on with battery but not always with power adapter only.
The only issue so far was the VCC of the BQ24780S that was fluctuating from 16 to 19 V so I replaced the IC and the PR209 so the VCC is stable now at 19,10V.
I have checked for shorts dc-in mosfets PQ201 & PQ202, PR206 & PR207 are ok, battery shunt resistors PR222 & PR224 have correct values, ACDET is 2,78V, ACOK 3,3V, PR201 has 19,5V.
At battery EC_SMCA & EC_SMDA are about 3,25V.
ACP to ACN pin loop is 1,1 Ohm

any help is appreciated

[mcplslg123]

Re: NM-C861 BQ24780S charging issue

Cmsrc/acdrv?

[rookieme]

Re: NM-C861 BQ24780S charging issue

they are 20,10V & 26,21V accordingly

I have a similar model [NM-C821] that uses the same charge circuit so I was able to compare them. The main difference is that the faulty one has 0,163V voltage drop at PR209 and the working one has only 0,027V.
Both the resistor and the IC have already been replaced as mentioned above.

One more hint is that led2 [orange light at dc jack port] usually stays on when the system is turned off and I disconnect the ac adapter, even if I use a charged battery.
The led2 is the BATT_LOW_LED# signal coming from kbc.

[mcplslg123]

Re: NM-C861 BQ24780S charging issue

The last hint is usually an indicator of problem in R2 in voltage divider circuit for gate pins of dc-in fets. You're experienced enough to take this clue and check R2 resistor out of circuit and if its correct try lowering the value of resistor by 5%. This should solve the dc jack light remaining on.

[rookieme]

Re: NM-C861 BQ24780S charging issue

The R2 resistor is at the SSD circuit.
The dc-in fets use the PR202 & PR206 so which one you mention?

[mcplslg123]

Re: NM-C861 BQ24780S charging issue

Hey,by saying R2 i mean the lower resistor(one which is connected to GND) in a voltage divider circuit. R1 is the resistor which has 19V at one end and other end is connected to R2. This how R1 & R2 is described in a voltage divider circuit. I hope now you can find it out .

[rookieme]

Re: NM-C861 BQ24780S charging issue

In this case the is no such divider as you can see at the photo

[mcplslg123]

Re: NM-C861 BQ24780S charging issue

In this case the is no such divider as you can see at the photo

Yeh, just had a look at the schematic and design it bit different. battery is charging? Only issue is not powering with adapter?

[rookieme]

Re: NM-C861 BQ24780S charging issue

The first issue was that it could not power on with adapter only and after replacement of the charging ic this was solved.
Now only issue it that battery is not charging and the orange light at the dc jack without ac which is more like a hint and not much of a problem.
Battery is good and tested in a working laptop.

[rookieme]

Re: NM-C861 BQ24780S charging issue

The first issue was that it could not power on with adapter only and after replacement of the charging ic this was solved.
Now only issue it that battery is not charging and the orange light at the dc jack without ac which is more like a hint and not much of a problem.
Battery is good and tested in a working laptop.

[Techtiger]

Re: NM-C861 BQ24780S charging issue

What is the supply voltage for JBAT1 with the battery and adapter inserted, specifically for pins 1 to 6, on the BQ24780S Additionally, what are the voltages for pins 18, 23, 24, 25, 26, and 27 , what is the supply and resistances PL 201?

[rookieme]

Re: NM-C861 BQ24780S charging issue

at JBAT pins
1,2 - 11,14V with & without adapter
3,4 - 3,33V with & without adapter
5 - 0,3V with & without adapter
6 - 0V with & without adapter

at BQ24780S pins with adapter
18 - 11,11V
23 - 0,16V
24 - 6,07V
25 - pulsing from 11 to 12,7V
26 - pulsing from 8,5 to 11V
27 - 12,7V

I'm not sure what you mean with the supply and resistances PL 201 but the resistance from pin1 to pin2 is zero and the the resistance to ground is 102k with black probe to ground and open circuit with red probe to ground.

[Udemzy]

Re: NM-C861 BQ24780S charging issue

at JBAT pins
1,2 - 11,14V with & without adapter
3,4 - 3,33V with & without adapter
5 - 0,3V with & without adapter
6 - 0V with & without adapter

at BQ24780S pins with adapter
18 - 11,11V
23 - 0,16V
24 - 6,07V
25 - pulsing from 11 to 12,7V
26 - pulsing from 8,5 to 11V
27 - 12,7V

I'm not sure what you mean with the supply and resistances PL 201 but the resistance from pin1 to pin2 is zero and the the resistance to ground is 102k with black probe to ground and open circuit with red probe to ground.

Have you check the vcc resistor to charging ic?

Also the ACN/ACP SRN/SRP communication with respective CLR to see if it communicate?

[rookieme]

Re: NM-C861 BQ24780S charging issue

Have you check the vcc resistor to charging ic?

Also the ACN/ACP SRN/SRP communication with respective CLR to see if it communicate?

Yes this was covered from post #1

[Techtiger]

Re: NM-C861 BQ24780S charging issue

at JBAT pins
1,2 - 11,14V with & without adapter
3,4 - 3,33V with & without adapter
5 - 0,3V with & without adapter
6 - 0V with & without adapter

at BQ24780S pins with adapter
18 - 11,11V
23 - 0,16V
24 - 6,07V
25 - pulsing from 11 to 12,7V
26 - pulsing from 8,5 to 11V
27 - 12,7V

I'm not sure what you mean with the supply and resistances PL 201 but the resistance from pin1 to pin2 is zero and the the resistance to ground is 102k with black probe to ground and open circuit with red probe to ground.

ensure that the -3V signal from JBAT pin 5 reaches pin 15 of PU201. Additionally, test the gate pulses of PQ205 and PQ206 again using oscilloscope. Confirm if pin 23 reads 0.16V; this voltage seems lower than expected

[rookieme]

Re: NM-C861 BQ24780S charging issue

JBAT pin5 has 10k resistance to pin15 of PU201 as it should.
Pin23 at PU201 is indeed that low.
Unfortunately I don't have an oscilloscope to test the gates.

I had some thoughts for the kbc [IT8227E-128 CXS] so I tried a IT8227E-128 CXA that I had available but I was unable to program it the correct EC dump even if I was able to read its dump.
Now I have put back the original kbc but I'm unable even to read its dump.
Should I order the CXS version of it to try?

[zanemirac14]

i have the same issue did you resolve this???

[mon2]

Carefully measure the voltage to ground of:

ACDET ; pin 6 on charger IC
ACOK ; pin 5
REGN ; pin 24
ACDRV ; pin 4

with the ac adapter plugged in. Meter in DC 30v scale or higher. Black meter probe to ground (shield is ok). Red probe to the pin to test. Be careful as the charger pins are live with power. Confirm your probes are fine tipped on your meter before starting.