I received this Toshiba Satellite C850 with no power, no light indicator. First I connected to 19v power supply to see the current reading. The current reading is zero. Even if I press power on there's no reaction on current.
I disassemble the unit, and check the board if it has a water spill. There's no water spill. I decided to perform voltage checking. I connected the 19v power supply and check the charging flex if there's a 19v coming. There it is. I then check the current sensing resistor if there's a 19v coming, but I only measured zero volt. What came to my mind was maybe 1 of the MOSFETS is deffective.
I measured voltage on the drain of the first MOSFET, there's a 19v. But when I measured its SOURCE, the voltage was almost zero. I doubt that the second MOSFET was deffective. I first measured the resistance of the first MOSFET, and it was good. I then measured the resistance of the 2nd MOSFET, and guess what I have found..... The second MOSFET was shorted!
To make it sure, I remove the second MOSFET. Then voltage check again on the SOURCE of the first MOSFET. There's now a 19v. Confirmed! The second MOSFET was the culprit. And it's an N-Channel MOSFET. After replacing it, the problem was solved.
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| TESTING |
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| DONE |
what are the mosfet numbers.. plz help.. I also have the same problem..
ReplyDeletethere are 2 type of mosfet.. n-type and p-type... you must determine what's your mosfet type.... there is no problem with mosfet part number...
ReplyDeletegreat site.keep the laptop repair articles coming.
ReplyDeleteuseful to me in uk.
How are you I have a laptop with the same problem.
ReplyDeleteI was trying to check the MOSFET if 19 volts is coming the lights started blinking I removed my tester.