Re: Lenovo Thinkbook 15-iil Problem - Need help
N Mosfet checked : No short
PR419 checked : 720 ohms
PR420 checked : 500K
(checked on board ie without desoldering)...
Eddy25
Member
Last Activity: 08-24-2021, 11:42 AM
Joined: 10-02-2014
Location: Paris
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Re: Lenovo Thinkbook 15-iil Problem - Need help
Thanks for this.
Meanwhile i've made some progress. I found that the middle pin of the AC adapter is connected to the pin1 of the NChannel Mosfet as shown in the attached picture and this corresponds to the schematic (also attached) related to a Lenovo different from the mine wich i used for guidance purpose since the schematic of the mine is not available.
Is the resistor you are referring to, indicated in the schematic and or the picture? and how to know it is faulty?...Last edited by Eddy25; 08-23-2021, 05:11 PM.Leave a comment:
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Re: Lenovo Thinkbook 15-iil 20SM
Yes it's that board number. Thanks anyway.
ps; is there a Lenovo schematic close to it for guidance purpose.? My concern is the circuit in the motherboard of the [B]"Adapter ID"[/B] signal (the middle pin of the rectangular slim pin connector)Re: Lenovo Thinkbook 15-iil 20SM
Yes it's that board number. Thanks anyway.
ps; is there a Lenovo schematic close to it for guidance purpose.? My concern is the circuit in the motherboard of the [B]"Adapter ID"[/B] signal (the middle...Last edited by Eddy25; 08-23-2021, 06:04 AM.Leave a comment:
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Re: Lenovo Thinkbook 15-iil Problem - Need help
Have tried to trace the circuit with beeper for several hours but i think it is pretty impossible without a circuit board since there are 6 or 7 layers with so many Vias. Have just found two solder points (test points i think..) that are connected to the middle pin that's all .
May be you have a trick on how to do that ?
Thanks anyway.
PS : Is the IT5570VG-128 the KBC ?...Last edited by Eddy25; 08-22-2021, 01:02 PM.Leave a comment:
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Lenovo Thinkbook 15-iil 20SM
Please schematic for Lenovo Thinkbook 15-iil 20SM. Thanks -
Re: Lenovo Thinkbook 15-iil Problem - Need help
Thanks for replying.
Is this resistor located near the KBC chip ?...Leave a comment:
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Re: Lenovo Thinkbook 15-iil Problem - Need help
Thanks for replying... Here are the results :
Pin3 (ACP) : 19.9v
pin2 (ACN) : 20v
Are these values correct?
Yesterday i disconnected the cmos battery and reconnected it. Then i plugged in the AC adapter, the laptop powered up for a few seconds and i got the following message on the display : [B]"An unknown adapter is connected to the system. To use AC power, please connect the AC adapter that was shipped with the system."[/B] and just after that it shuts down. I'm...Last edited by Eddy25; 08-21-2021, 05:28 AM.Leave a comment:
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Re: Lenovo Thinkbook 15-iil Problem - Need help
Yes i am sure it is a BQ25710 a Texas Instruments SMBus Narrow VDC Buck-Boost Battery Charge Controller.
Here is attached it's datasheet....Leave a comment:
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Re: Lenovo Thinkbook 15-iil Problem - Need help
Here is a picture of the dc input zone.
What is the yellow device marked as T ? because i have noticed that it's shorted (unless it is a very low resistor or a fuse)
The 2 grey capacitors connected to the source of the first dc in mosfet are also shorted! Could this be the problem ?...Last edited by Eddy25; 08-15-2021, 01:03 PM.Leave a comment:
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Re: Lenovo Thinkbook 15-iil Problem - Need help
Thanks for helping.
Have checked the 2 input mosfets (Pchannel mosfets) and there are no shorts. Their voltages are as follows :
Source : 20v for both
Drain : 20v for both
Gate : 10v for the first and 9.6v for the second.
As for the test points my ic charger is BQ25710 and not 24715 like in your schematic. So I have made the following measurements :
pin1 (Vbus) : 20v
pin4 (CHRG_OK) : 2.9v
pin12 (SDA) : 3.2v
pin13 (SCL) : 3.2v
pin31 (HIDRV1)...Leave a comment:
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Re: Lenovo Thinkbook 15-iil Problem - Need help
To recapitulate here is the situation :
-The laptop power on normally with the battery connected (AC adapter disconnected)
-With battery disconnected and AC adapter connected the power on led around the power button lights ON but noting happens when i press the power button.
- With the AC adapter connected the 20v rail is ok. (by the way where can i check the 5v and 3.3v?)
Please help what could be the problem?
PS : Have tried with another AC adapter without result.Last edited by Eddy25; 08-15-2021, 03:24 AM.Leave a comment:
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Re: Lenovo Thinkbook 15-iil Problem - Need help
Have measured the voltage at both sides of the 0.01 ohm sensing resistor and found the correct value of 20v. Have also measured the voltage at pin 1 of the charge controller IC (BQ25710) and also found the correct value of 20v.
What to check else ?Leave a comment:
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Re: Lenovo Thinkbook 15-iil Problem - Need help
Since i don't know exactly where are the DC IN Mosfets, i have measured the voltage of the 4 mosfets situated near the sensing resistor and the battery connector. I have marked them as 1 , 2, 3 and 4 in the attached picture.
Here are the results :
Mosfet 1 :
pin 1,2,3 : 2.5v
pin 4 : 3.7v
pin 5,6,7,8 : 9.1v
Mosfet 2 :
pin 1,2,3 : 0v
pin 4 : 3.65v
pin 5,6,7,8 : 2.5v
Mosfet 3 :
pin 1,2,3 : 0v
pin 4 : 4.7v
...Leave a comment:
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Re: Lenovo Thinkbook 15-iil Problem - Need help
Sorry for a wrong information i gave. The actual voltage of the AC charger is 20v measured with a professional multimeter loaned from a friend. (I was using a cheap faulty multimeter...). So now the problem seems to be the power supply circuit since the laptop have been running without problem with just the battery connected.
Here is a picture of the area around the DC input to the motherboard.
Have i to dismantle the motherboard and take pictures on the other side?...Leave a comment:
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Re: Lenovo Thinkbook 15-iil Problem - Need help
My charger is branded Lenovo. I got it together with the laptop and it's ouput voltage is rated 20v but when measuring (without any load) it gives 28v!
When using an external power supply dialed at 20v how to deal with the data pin (the center pin of the original slim pin rectangular connector) ie can the laptop be powered without connecting the data pin? Thanks.Leave a comment:
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Lenovo Thinkbook 15-iil Problem - Need help
Hi Guys.
At first please excuse my poor english.
Here is my situation : My Lenovo Thinkbook 15-IIL Model 20SM no more power up using the AC charger. It power up without problem when using the battery without the connecting the AC charger. Meanwhile the battery is totally discharged and now i can no more power it up. Have opened it and disconnected the battery connector and connected the AC charger but it won't power up.
Have measured the voltage across the DC output pins of the charger and found 28v and not 20v as the charger is rated. Could this be the problem?
Is there...Last edited by Eddy25; 08-12-2021, 09:58 AM. -
Re: New Members - please post your introductions here
Hi Guys. I'm pleased to join this lovely forum. Have found it when trying to fix a dead laptop.Leave a comment:
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