I know that in some cases where the laptop does not boot it is possible to bypass the first mosfet to make it boot again but how safe is it and what's the worst that can happen?
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OpenBoardView — https://github.com/OpenBoardView/OpenBoardView -
Re: Bypass mosfet safety
This is from the TI BQ24780S datasheet. You can learn a lot by reading these.
"The ACDRV drives a pair of common-source (CMSRC) N-channel power MOSFETs (ACFET and RBFET) between adapter and ACP. The ACFET separates adapter from system and battery, and provides a limited di/dt when plugging in adapter by controlling the ACFET turn-on time. Meanwhile, it protects the adapter when the system or battery is shorted. The RBFET provides negative input voltage protection and battery discharge protection when adapter is shorted to ground, and minimizes system power dissipation with its low RDS(on) compared to a Schottky diode."
Shorting out the first MOSFET is a hack used by some when troubleshooting, but it's not something that should be left that way. Most controllers will disable charging the battery if this FET is bypassed. Additionally, leaving it shorted no longer protects the system/charger from surges when plugged in, and provides no overvoltage protection.Comment
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I tried to use this method:
Testing an N-channel MOSFET:
Step 1: Discharge the Gate (turn off the MOSFET)
Place the black probe (COM) on the Source (S) and the red probe on the Drain (D). The multimeter should show no continuity (high resistance or "OL" – open line).
Then, touch the black probe to the Source (S) and the red probe to the Gate (G). This discharges any stored charge in the Gate, turning the MOSFET off.
Step 2: Charge the Gate (turn on the MOSFET)
Now, place the red probe on the Gate (G) and the black probe on the...09-27-2024, 03:31 AM -
Hello everyone, I recently found this badcaps site and super Learn Electronics Repair youtube channel. And I wanted to learn how to troubleshoot power supplies and VGA cards and how to practice soldering, since I already have a properly defective piece of them. I am currently trying to solve two problems:
I have a Gigabyte GV-RX460WF2OC-4GD type card. I managed to find the faulty MOSfet (AON6414A) on it, which I replaced. The card starts up, but after about half a minute, the MOSfet in the same position will be shorted again. Is it possible that the PWM controller driving the MOSfet... -
I have a Razer laptop (RZ09 MB# CH570_MB_NT) that has a shorted mosfet marked BND M03 E067 that I'm unable to find anywhere online. Does anyone either know what the part number is for this mosfet or have a schematic I can find it in?
Backstory on the whole thing the laptop was plugged into a lamp at a hotel. The lamp got unplugged while it was charging and now the system won't power on anymore. I found the caps around this mosfet shorted and when I injected voltage into the caps the mosfet got hot and my bench psu was pulling 5A. Pretty sure this is all that's wrong with the laptop... -
Hey guys,
i have a asus motherboard here and as the title says after the first mosfet (in the picture) there is nothing more than 3.15v.
I injected 19v and max. 1 amp at the charging port and there is not voltage drop or smth. It's just taking 19v and 1 milliamp.
Then i tried to inject 19v and max 1amp after the current sensor and there it first takes 19v and 4 milliamps and after 2 seconds it is taking nothing (no current).
I measured on the coils on board everything seems fine. Also the main power rail is not shorted (infinite resistance).
Now i thought something... -
The board number is GU502DU. I repaired this a couple weeks ago and it came back with the same issue, same mosfet failed (PQH9201). I'm hoping that the GPU was spared this time.
I used the same replacement part (purchased from Mouser) and I'm certain the soldering was done properly since it took just as much effort to remove as before. What could cause this same mosfet to fail? I'm thinking if it was unsuitable then the others would fail too. I looked for similar failures on YTube and the mosfet was replaced with AOE6930 in one instance and AOE6932 in the other but it's possible that the...
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