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hameeds01
Joined: 23 Aug 2005
Posts: 104
Helped: 1
Location: NUST Islamabad
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 12 May 2008 16:24 How to test MOSFET |
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| How to test N or P channel MOSFET using digital Multi Meter, how to determine its Gate Drain & source pins via DMM
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FvM
Joined: 22 Jan 2008
Posts: 2488
Helped: 409
Location: Bochum, Germany
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| 12 May 2008 16:50 Re: How to test MOSFET |
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It's generally not necessary to check the pin mapping, cause no manufacturer uses a mapping different from industry standard (as far as I know). Polarity can be determined with a multimeter/diode tester from the drain source reverse diode.
If threshold voltage is below diode tester maximum (e. g. 2 V), also identification of a three-terminal blackbox-FET would be possible, but usually it's not necessary.
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forkschgrad
Joined: 06 Apr 2007
Posts: 284
Helped: 8
Location: Philippines
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| 12 May 2008 18:32 Re: How to test MOSFET |
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| test the pn junctions.
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faraz101
Joined: 07 Mar 2007
Posts: 93
Helped: 2
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| 19 May 2008 6:01 How to test MOSFET |
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first connect dmm red lead to drain and black on the source.(meter should be on diode test mode)
in first case drain to source will be open.
then connect meter red probe to gate and black to source and again connect the red probe to drain and black with source.now it will show the short circuit.after this short the gate and sorce with some wire now again drain to source will show open circuit.
it means that mosfet is good
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randell_xtian
Joined: 25 Mar 2008
Posts: 150
Helped: 8
Location: Philippines
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| 19 May 2008 6:09 Re: How to test MOSFET |
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MOSFET TESTING
Another type of semiconductor you should become familiar with is the metal oxide semiconductor field-effect transistor (MOSFET), as shown in figures 2-19 and 2-20. You must be extremely careful when working with MOSFETs because of their high degree of sensitivity to static voltages. As previously mentioned in this chapter, the soldering iron should be grounded. A metal plate should be placed on the workbench and grounded to the ship’s hull through a 250-kilohm to 1-megohm resistor. You should also wear a bracelet with an attached ground strap and ground yourself to the ship’s hull through a 250-kilohm to 1-megohm resistor. You should not allow a MOSFET to come into contact with your clothing, plastics, or cellophane-type materials. A vacuum plunger (solder sucker) must not be used because of the high electrostatic charges it can generate. Solder removal by wicking is recommended. It is also good practice to wrap MOSFETs in metal foil when they are out of a circuit. To ensure MOSFET safety under test, use a portable volt-ohm-milliammeter (vom) to make MOSFET resistance measurements. A vtvm must never be used in testing MOSFETs. You must be aware that while you are testing a MOSFET, you are grounded to the ship’s hull or station’s ground. Use of a vtvm would cause a definite safety hazard because of the 115-volt, 60-hertz power input. When the resistance measurements are complete and the MOSFET is properly stored, unground both the plate on the workbench and yourself.
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forkschgrad
Joined: 06 Apr 2007
Posts: 284
Helped: 8
Location: Philippines
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| 19 May 2008 15:55 Re: How to test MOSFET |
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| where are the figures?
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FvM
Joined: 22 Jan 2008
Posts: 2488
Helped: 409
Location: Bochum, Germany
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| 19 May 2008 16:16 Re: How to test MOSFET |
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| The precautions said by randell_xtian are necessary without doubt for unprotected small-signal MOSFET, particularly small geometry RF devices. Power MOSFET are more or less protected and have high gate capacitances that need a lot of charge accumulated to create dangerous voltages, I would expect an ESD susceptibility not higher than for small-signal bipolar devices. Usual ESD protective equipment is recommended in a professional enviroment anyway.
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randell_xtian
Joined: 25 Mar 2008
Posts: 150
Helped: 8
Location: Philippines
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| 21 May 2008 3:24 Re: How to test MOSFET |
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pls. check the attachment:
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