Meter in resistance mode. Measure the resistance from pin #4 (gate) of each of these mosfets to pin #32 of the charger ic. We are trying to locate which one of these mosfets is being driven by the charger ic (BGATE).
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Ok so Pin 32 to Gate of the 21321 MOSFET is 0.3 ohms
Looking at that other MOSFET I sent a picture of, I just noticed it has 2 gates so maybe I never measured that one properly. Hopefully the 21321 MOSFET is the one we are looking for.Comment
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Yes, 21321 is the battery mosfet and the resistance check looks to be ok.
Here is the datasheet for this P-channel mosfet:
AONR21321 Datasheet | DigiKey
Locate the high side mosfet driven by the same charger IC. We are hunting for a mosfet that is possibly leaking. The other mosfet found in the earlier post looks to be low in resistance and is a suspect. Review where the pin # 4 of that mosfet travels to the charger IC. It is possible that there will be a current limit resistor between the charger IC pin and the mosfet's gate pin.
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Ok pin 4 of the top (there are two) QA3112 goes to pin 7 (LGATE2) of the charger IC.Comment
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Pin 4 of the bottom MOSFET goes to pin 9 (LGATE1)Comment
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I'm really appreciating your help by the way 🙏🤩Comment
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Continue to hunt for the mosfet mated with the UGATE2 pin on the charger IC using the same method. One meter probe on UGATE2 pin on the charger IC; other meter pin on pin # 4 of the mosfet.
Once that mosfet is located, proceed to test that mosfet using resistance mode (if manual mode meter, use a higher resistance scale). If you read 'OL' = over limit, switch to a higher resistance scale on the meter.
Measure the mosfet as follows:
source (1-2-3) & drain (5-6-7-8)
source (1-2-3) & gate (4)
gate (4) & drain (5-6-7-8)
Post each measurement.Comment
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Ok so UGATE2 of the charger IC goes to the MOSFET in the picture. I'm a little confused by it as it does not have a 1234 drain. Hopefully I've measured right but I'm unsure of the different layout of pins on this chip compared to your traditional MOSFET.
Here is what I got with my effort -
Source to drain - 0.9 M ohms
Source to gate - 3.6 M ohms
Gate to drain - 500 K ohms.
Attached FilesComment
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Good point and bad assumption on my part. Consult the datasheet and measure again to hunt down the respective gate / drain / source pins for this dual mosfet.
PS: Need to make a quick trip to Detroit - BBL.
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Ok safe trip.
I checked the 3 pins on one side of the mosfet and they all go to Ground 🤷 (see pic)
The 3 on the other side obviously don't. The datasheet shows 3 Source pins and 3 Drain pins. 3 of these pins are grounded so I assume that MOSFET is shorted to ground?
I have a thermal cam so will try it while your on your trip and let you know the results.Attached FilesComment
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Thermal cam showed nothing.Comment
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I did notice when I turned the laptop on, that the chipset was starting to heat up for the 3 seconds before it starts looping on and off, I assume this is normal?Comment
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Which chipset?Comment
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I simply dont understand why we're after charging circuit when the system is charging battery?
The resistance to GND for cpu coils is perfectly fine-so SOC is not shorted.Comment
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Is it at all possible that the laptop is switching on and off because of a corrupt BIOS?
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Backup the original bios and test with a known good bios. If necessary, post your request for a fresh bios inside the bios forum.Comment
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Hi.
Tried a new BIOS but the laptop is doing the same on and off every 3 seconds with no picture. Time to move on to the next step I think. 🤔Comment
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On the CPU inductors, I'm getting 35 ohms. I might be wrong but that sounds high to me?Comment
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Can you measure the 2nd mosfet again from post # 20 and post your measurements. The first measurement looks very low for a good mosfet.
On the CPU resistance, it is not shorted with such a value.Last edited by mon2; 07-06-2024, 02:49 PM.Comment
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