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?
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Last edited by SMDFlea; 12-28-2023, 04:53 PM. -
Secret is in the tea leaves as posted in the above sticky by piernov on charger circuits.
Laptop battery charging circuit - Badcaps -
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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