Background: (Please skip to "Question" section if you don't wanna read alot)
I have gathered about a dozen broken power supplies from 2+ years of computer tech work. Recently I've fixed two of them (blown thermistors, replaced with good ones) - and as some of you might know, the third one just needs one more cap replacement. Fourth one also needs recapping. A few were beyond repair, so I scrapped them for whatever parts were good.
Mysteriously, the rest of my power supplies look just fine. No burn marks on the board, no leaky caps. Fans, thermistors, and fuses all work. But the power supplies them selves don't. However, about 2 or 3 of them have a working +5V standby rail.
Now I'm thinking that the mosfets may be problematic. I learned online(hardwaresecrets and other electronics sites) that a mosfet is a type of transistor, and has a Gate, Drain and Source and are used to rectify current, which is a part of the AC-DC conversion process. Many of them are N-type and the rest are P-type. 3-pin diodes, which look very much like a mosfet are also used in the rectification process.
Different sites show different ways of testing mosfets. Some instructions are quite ambiguous and hard to follow. One youtube video(lost the link) even shows a guy using a motor and a big current on the drain-source connection while using a small current on the gate to see if the motor spins. I've tried that(9V lead to drain, with 3k resistor lead to gate) and some of my mosfets have failed to spin the motor while passing the multimeter tests.
I would like to know of a sure way of testing mosfets. So..
Question:
1. What is your preferred method of testing mosfets?
2. Also, is it unsafe to use a spring-loaded "plunger" solder sucker to remove the mosfet from circuit board? Some sites say that it creates lots of static electricity, which is bad.
I have gathered about a dozen broken power supplies from 2+ years of computer tech work. Recently I've fixed two of them (blown thermistors, replaced with good ones) - and as some of you might know, the third one just needs one more cap replacement. Fourth one also needs recapping. A few were beyond repair, so I scrapped them for whatever parts were good.
Mysteriously, the rest of my power supplies look just fine. No burn marks on the board, no leaky caps. Fans, thermistors, and fuses all work. But the power supplies them selves don't. However, about 2 or 3 of them have a working +5V standby rail.
Now I'm thinking that the mosfets may be problematic. I learned online(hardwaresecrets and other electronics sites) that a mosfet is a type of transistor, and has a Gate, Drain and Source and are used to rectify current, which is a part of the AC-DC conversion process. Many of them are N-type and the rest are P-type. 3-pin diodes, which look very much like a mosfet are also used in the rectification process.
Different sites show different ways of testing mosfets. Some instructions are quite ambiguous and hard to follow. One youtube video(lost the link) even shows a guy using a motor and a big current on the drain-source connection while using a small current on the gate to see if the motor spins. I've tried that(9V lead to drain, with 3k resistor lead to gate) and some of my mosfets have failed to spin the motor while passing the multimeter tests.
I would like to know of a sure way of testing mosfets. So..
Question:
1. What is your preferred method of testing mosfets?
2. Also, is it unsafe to use a spring-loaded "plunger" solder sucker to remove the mosfet from circuit board? Some sites say that it creates lots of static electricity, which is bad.
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