Lenovo Thinkpad E495 no loading

[danny34]

Hello guys,
I'm new here and I hope you can help me. 😍
My Thinkpad E495 no longer charges. I took some measurements on the BQ25700A with Battery and USB connected.
I attached the Schematic. On Page 56 there is the BQ25700A.

I was able to find a defective mosfet, the PQ101. Unfortunately the battery is still not charging.
Can you see from the measurements where I could look further?

BQ25700A:
Pin 1 VBUS: 20V
Pin 2 ACN: 20V
Pin 3 ACP: 20V
Pin 4 CHRG_OK: 0V & contact to GND
Pin 5 ENZ_OTG: 0V
Pin 6 ILIM_HIZ: 3,3V
Pin 7 VDDA: 7,4V
Pin 8 IADPT: 0-2,5V Pulse
Pin 9 IBAT: 0V
Pin 10 PSYS: 0V
Pin 11 PROCHO#: 0V & contact to GND
Pin 12 SDA: 3,3V
Pin 13 SCL: 3,3V
Pin 14 CMPIN: 2,6V
Pin 15 CMPOUT: 0,06V
Pin 16 COMP1: 0,16V
Pin 17 COMP2: 1,24V
Pin 18 CELL_BATPRES: 4,4V
Pin 19 SRN: 11,5V
Pin 20 SRP: 10,9V
Pin 21 BATDRV#: 10,9V
Pin 22 VSYS: 11V
Pin 23 SW2: 11V
Pin 24 HIDRV2: 11V
Pin 25 BTST2: 10,8V
Pin 26 LODRV2: 0V & contact to GND
Pin 27 PGND: 0V
Pin 28 REGN: 7,4V
Pin 29 LODRV1: 0V
Pin 30 BTST1: 10,8V
Pin 31 HIDRV1: 10,9V
Pin 32 SW1: 11V

Thank you very much. I just do not get any further 😥

LINK to schematic --> https://www.badcaps.net/forum/troubl...nm-c061-schema

[mon2]

Hello. Welcome. Remove all power. Remove the battery.

Meter in lowest resistance mode scale. Measure the resistance directly at the charger IC pins 19 & 20. What is the resistance in ohms?

Pin 19 SRN: 11,5V
Pin 20 SRP: 10,9V

This is too large of a voltage drop across the 2 pins and the charger IC can sense this delta and forcing the charging function to disable.

[danny34]

Thanks for your help.
I measured 27.3 ohms between pins 19 & 20.

[mon2]

This measurement is too high. It should be ~20 ohms. Touch your meter probes together so we can understand the lowest measurement possible for your meter.

What is the resistance when you short your probes?

That is the overhead of your meter during such measurements. Respectively, then check the resistance across each of the resistors in this battery current sense loop.

Measure the resistance across PR113 and then of PR114. Each should be ~10 ohms. Confirm each measurement.

[danny34]

Resistance between probes = 0.00 Ohms
i have a Fluke 117

PR113 = 17,3 Ohms (should be 10)
PR114 = 10,0 Ohms

[mon2]

Agreed. Replace PR113 and test again. The schematic notes 5% accuracy for the component but 1% should be quite cheap as well.

RMCF0603FT10R0 Stackpole Electronics Inc | Resistors | DigiKey

[danny34]

I have an SMD area at work. I'll get the resistor tomorrow and solder it in and give feedback! Thank you so much!🤗

[danny34]

Unfortunately, the employees do not have the matching resistor. I'm ordering the resistor now and will let you know when I've soldered the resistor in.

[danny34]

I replace the resistor. Now the resistance between pin 19 & 20 is 20,2 ohms.
But the battery still not charge...

I repeat the measurements on the BQ27500:


Pin 1 VBUS: 20V
Pin 2 ACN: 20V
Pin 3 ACP: 20V
Pin 4 CHRG_OK: 0V
Pin 5 ENZ_OTG: 0V
Pin 6 ILIM_HIZ: 3,3V
Pin 7 VDDA: 7,4V
Pin 8 IADPT: 0V
Pin 9 IBAT: 0V
Pin 10 PSYS: 3,3V
Pin 11 PROCHO#: 0V
Pin 12 SDA: 3,3V
Pin 13 SCL: 3,3V
Pin 14 CMPIN: 2,6V
Pin 15 CMPOUT: 0,06V
Pin 16 COMP1: 0,16V
Pin 17 COMP2: 1,24V
Pin 18 CELL_BATPRES: 4,4V
Pin 19 SRN: 11,5V
Pin 20 SRP: 11,2V
Pin 21 BATDRV#: 10,9V
Pin 22 VSYS: 11V
Pin 23 SW2: 7V
Pin 24 HIDRV2: 7V
Pin 25 BTST2: 7,5V
Pin 26 LODRV2: 0V
Pin 27 PGND: 0V
Pin 28 REGN: 7,4V
Pin 29 LODRV1: 0V
Pin 30 BTST1: 7,5V
Pin 31 HIDRV1: 7V
Pin 32 SW1: 7V

[danny34]

And now without Battery connected:

Pin 1 VBUS: 20V
Pin 2 ACN: 20V
Pin 3 ACP: 20V
Pin 4 CHRG_OK: 0V
Pin 5 ENZ_OTG: 0V
Pin 6 ILIM_HIZ: 3,3V
Pin 7 VDDA: 7,4V
Pin 8 IADPT: 0V
Pin 9 IBAT: 0V
Pin 10 PSYS: 0V
Pin 11 PROCHO#: 0V
Pin 12 SDA: 3,3V
Pin 13 SCL: 3,3V
Pin 14 CMPIN: 0,4V
Pin 15 CMPOUT: 0,4V
Pin 16 COMP1: 1,24V
Pin 17 COMP2: 1,24V
Pin 18 CELL_BATPRES: 0V
Pin 19 SRN: 0,8V
Pin 20 SRP: 0,8V
Pin 21 BATDRV#: 9,2V
Pin 22 VSYS: 9,2V
Pin 23 SW2: 0V
Pin 24 HIDRV2: 0V
Pin 25 BTST2: 6V
Pin 26 LODRV2: 6V
Pin 27 PGND: 0V
Pin 28 REGN: 6V
Pin 29 LODRV1: 6V
Pin 30 BTST1: 6V
Pin 31 HIDRV1: 0V
Pin 32 SW1: 0V

[danny34]

what I forgot to mention:
If you charge the battery in another Thinkpad and install it again, the notebook runs without any problems. Of course it still doesn't load.

But it doesn't start without a battery or with an empty battery even with the power supply plugged in, although 20v comes out of the USB socket...is this normal?

[mon2]

the notebook runs without any problems. Of course it still doesn't load.

Can you clarify? The notebook powers up and starts to boot with graphics? Then crashes during the loading of Windows?

[danny34]

sorry. my english is not that good. What I meant was that the battery wasn't charging. Windows starts completely and runs without any problems.

but unfortunately only with battery.
As soon as the battery is empty or is removed, it will not work with the original power supply. Various power supplies have already been tested and the 20V even comes up to the BQ27500, as described in my previous posts.

[mon2]

Pin 4 CHRG_OK: 0V

This signal is never a logic '1'. Stuck @ logic '0' for both cases - with adapter only; with adapter+battery combination. When the adapter is connected, this signal must be a logic '1'.

The logic '1' is created through a pull-up resistor and a pull-up voltage of +3VL.

Confirm the voltage to ground of +3VL. Check at PU201, pin 5.

Follow the power path of +3VL. Confirm that this LDO is created by the regulator. If not, stop. Remove all power. Measure the resistance to ground (in ohms) of +3VL.

[danny34]

I checked it once as far as I understood.
+3VL is available with 3.3V. However, the other voltages on PU201 do not seem to be correct. I painted the measured values into the following image.

On the UE1 I was also able to measure the +3VL_EC with 3.3V which also arrives at 6 inputs from the UE1. I didn't detect any voltage at pin 11 (VCC) of UE1. This voltage should be +3VS.

Since I was looking for this +3VS, I found the U13.
I measured the U13 and didn't find any voltage either.

Unfortunately I didn't understand the last image with ACIN. Pin 4 of the charger is the 20V, right?
If that is the case, this contact should go to the ACPRN of UE1 (pin 108). But only 0V arrives there. and there is no contact with pin 4 of the USB-C socket.

[mon2]

+3VS is a rail that is created by +3VALW and is passed through the load switch (solid state relay) @ U13 provided the enable signal on pin #3 is active '1'.

Confirm that you have +3VALW present. Confirm the voltage to ground of pin #3 = 3VSON. If both of these signals are present and you still do not have a voltage at +3VS, then remove all power. Meter in resistance mode.

Measure the resistance to ground of +3VS to check if there is a shorted part on this low current rail.

[danny34]

No voltage comes in or out of any pin on the U13. Resistance to ground of +3VS is 2.5kohm.

I measured again on the PU201 (SYX198B). 9V arrives at pins 7 & 8. According to the schematic image there should be +3V_VIN...

As you can see from my image from my previous post, only 0V comes out at pin 4 (OUT).

[danny34]

To see why the PU201 had 0V on the EN1, I traced the conductor path and came across the PR206 (20k). This one is fine. There is also the PQ201 and I measured the following voltages on it:

[danny34]

If I understood correctly, EC_ON2_3V will come from PU1901 pin 16. There is 0V there. That's why I measured VCC of this PU1901 and there is 0V instead of +5VALW. I measured for +5VALW everywhere where this 5V should be present, but it was always 0V. So I continued looking for where this +5VALW came from.
They come from PU202!
At the PU202 at pin 5 (VIN) there is 9V, but at pin 6 (EN) there is only 0V instead of 5V.
So it's due to the missing EC_ON_5V. Unfortunately I can't find where EC_ON_5V comes from.

[mon2]

Search for net name EC_ON_5V on sheet 42 of the schematics.