Dear friends. I am working on a LENOVO THINKBOOK 15 G4 IAP Motherboard No: LA-L931P REV 01. The motherboard turns ON fine with or without battery & AC power, & battery charging is good too. This is for the first time till the power adapter is plugged in. When Laptop is in ON position, as soon as I remove the USB-C main power & plug it back again +20V_VIN is no longer there (Missing) & battery does not charge at all., I thought that the TPS65994-AE Chip was bad., so replaced it with a new good chip, but the problem is still there. On the battery charging chip BQ25710 where pins (VBUS,ACN & ACP) should have the +20V_VIN, all gone. Then I have to remove the battery again to getting the motherboard working & having the battery being charged again. I had a good test battery for this model, but still the same problem. If some repairs tips are offered, it would make the trouble shooting much easier. Schematics & Boardview both available here. Thanks in advance.
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Review the mosfets on the attached page. Each is a suspect. Remove all power. Meter in resistance mode. Measure the resistance across each of the DCin mosfets:
source (1-2-3) & drain (5-6-7-8)
source (1-2-3) & gate (4)
gate (4) & drain (5-6-7-8)
Each measurement must be hundreds of k ohms or higher else is a suspect and part may be defective.
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Thanks mon2 for the tips., I checked all the 4 MOSFET & all were 100% ok. Upon more trouble shooting, found that this chip gets very hot, it the 5VALW chip & the number printed on the chip is QrFHB. I have this chip in stock SY8386BRHC (Qq). Is this chip the same as SY8386CRHC (Number printed on the schematics)??? or I have to find the correct chip SY8386CRHC. I was checking AE, I could not find this number. Thanks dearComment
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Hi. How is the great weather there? Crazy hot here.
No - cannot replace theSY8386CRHC with SY8386BRHC - there are differences. Measure the resistance to ground of the output of the SY8386CRHC.
Pins # 12 & 13 do not match between the 2 different parts.Comment
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mon2., It's like placing a Hot HEATER in front of us. All of a sudden 18 days of continous heat, hope does not last for long.
The resistence of both the pins 11 & 12 are in Mega ohms (Chip Removed). Actually how I found this chip being defective, there was a short on all input caps & this chip getting hot. I removed the caps first but the short was present. Once I removed the chip, short gone. Hopefully this chip is defective. I found the Chip Qr on AE, easily available. I will order it today. Thanks for the help till the chip comes in. TCComment
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I have a Lenovo ThinkBook 15 G4 AMD (HLXB5 LA-M062P) that, when the battery is connected, starts up and shuts off in about 10 seconds, even when connected to power supply via USB-C charger. When the battery is disconnected, the computer stays on as in normal/expected operation (powered by USB-C charger input). I bought a new battery and see the exact same thing. My conclusion is it is not the battery itself but maybe some circuit or component involved in battery/DC-in crosstalk. I found a schematic but not boardview (request link below - sorry for the formatting, I'm not sure how to make an inline...02-25-2025, 11:33 PM -
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Hello, first of all, excuse me, I am using the translator, English is not my native language.
I have a Lenovo ideapad 330S - 14IKB laptop.
The tablet did not recognize me when I connected it, so I checked the device manager and I realized that there were many with the exclamation mark, so one by one I began to update their drivers until the sign disappeared of admiration, I even updated the BIOS, and the laptop rebooted normally and worked, so far so good, but the tablet still did not recognize me, I read on the internet that it could be due to a...
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