I'm curious as to what this is an indication of. I've got an HP laptop here with a slowly blinking caps lock key but no boot. The machine is alive electrically as it draws nearly 2A. I'm measuring 20v at the first mosfet input, but coming out of that mosfet I get only 3v. What is that an indication of?
HP 15-ay018nr LA-D704P. 20v to first mosfet, but 3v after
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Secret is in the tea leaves as posted in the above sticky by piernov on charger circuits.
Laptop battery charging circuit - Badcaps -
Secret is in the tea leaves as posted in the above sticky by piernov on charger circuits.
Laptop battery charging circuit - BadcapsComment
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You need to review the charging circuit and dc-in mosfets. Give us resistance measurements of dc in fets between
01.S-G
02.S-D
03.G-D
Voltage measurement of ACDET/REGN.
Are you powering the machine with dc supply or original adapter?Comment
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mcplslg123 I was powering with a bench supply. I can usually hold my own here in the forums, understanding what I'm told, but I'm blanking out on your abbreviations S-G, S-D, G-D and ACDET/REGN. Can you dumb it down a little bit please?
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Perform the resistance checks on the mosfets.
S-G = source & gate
S-D = source & drain
G-D = gate & drain
Post each measurement. No power during resistance checks. Checking for a low resistance = leaky mosfet = needs to be replaced if the resistance is still low after removal off the logic board.
ACDET and REGN are the pins on the charger IC. ACDET must be above a certain voltage threshold to validate that the power adapter is present. REGN is the LDO rail created by the charger IC and should be ~6 volts if all is well.Comment
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When using dc supply,set voltage at 20V and not 19V. If you set dc supply at 19V,this board doesnt allow to pass 19V thru 1st dc -in mosfet. I assume you are using HP PS_ID dongle or original hp cable with your dc supply.Comment
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by JaneI 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 -
by NooyHello 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... -
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... -
by MicroSMD LabThe 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... -
by ScotchmistI have an Asus GA502D, it had a blown mosfet which I replaced and the laptop booted into windows, a few mins later it shut off, the same mosfet was blown. I thought maybe just a bad mosfet but same thing happened again, a few mins in windows and shuts off.
I have removed the mosfet and can run the laptop no problem
The MOSFET is FDPC5018SG
Can anyone point me in the direction of what could be the cause of this, could it be the controller rt3663bc?
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