![]() It would also indicate to me that if this damage is caused by voltage surge that my 28 pin uP or PDIP or EPROM or whatever it is, is still good.How to Test a Transistor & a Diode with a Multimeter It is very quick and easy to learn how to test a transistor and a diode with a analogue multimeter - normally this is good enough for most applications. If the Patient Lift then is intermittent going up and works great going down, I figure I’m on the right path looking for twin components, but the list is short. One thing I was going to try the next time I get to the client is to reverse the up and down connections of the rocker switch. Having trouble proving the failing component. In looking for twin components (one for up and one for down) these MOSFETs show up on the list, but the quick test above shows them passing. Lifting works normally but lowering is quite intermittent so the Patient Lift cannot be used. Now that I have the MOSFETs out of the circuit, can I attach a power supply with 40-50 volts for a while with clips? And would I try to measure Ohms? This PCB is the motor control for a winch that lifts and lowers a human. The Vds spec for the 2SK2049 is 60V and the Vds for the IRFZ24N is 55V. This PCB repair project is at under “Patient Lift Aid Repair” where scrolling down to Documentation has component photos, BOM in Excel with hyperlinks to digikey parts, and a schematic done in Eagle. Is there way to test, or stress test these with a load over a minute or two since I have an intermittent failure? I want to test two K2049 (I’m told modern equivalent is 2SK2049) and two IRFZ24N. And yes you smart safe guys, I knew to discharge my hands first. Super helpful method This is the “get it done” version of testing I needed to know without having to go get more equipment. ![]() Make sure you use a meter that have the times 10k ohm range selector. This type of meter will not have enough power to trigger the FET. Some analog multimeter have the times 100k Ohm range, this type of meter can’t really test FET due to the absent of 9 Volt battery inside the multimeter. What you do is to switch the probe polarity when checking the P channel. Testing the P channel FET field effect transistor is just the same way as when you check N channel FET. If you notice that all the result that you measured kicked towards zero ohms and will not discharge, then the FET is considered shorted and need replacement. Once you know the secrets, testing other FET is as simple as testing diode. You need to practice more by taking some FET from your bench or from your component’s compartment. This will eventually discharge the internal capacitance again.Īt this time, use the red probe to touch on the source pin again, the pointer would not kick at all because you have already discharge it by touching the gate pin. To discharge the FET you must lift the red probe and touch just one time on the gate pin. Lifting the red probe from the source pin and putting it back again to the source pin, the pointer will remain at the middle of the meter’s scale. ![]() Use your finger to touch on the gate and drain pin. Use your right finger and touch the gate and drain pin together and you will notice the analogue multimeter pointer will move forward to center range of the meter’s scale. Now move the red probe to source pin while the black probe still touching the drain pin. Touch the gate pin with the red probe to discharge any internal capacitance in the FET. Assuming you are testing the n channel FET then put the black probe to the drain pin. Once you have the cross reference or diagram for each pin of the FET, then you can use your analogue multimeter set to times 10K ohm range to check the FET. FET failure and leakage are quite high in a circuit and you need to know how to accurately test it.įirst you will need to find which lead is the gate, drain and source pinout from semiconductor cross reference book or a datasheet. You will find them in power supplies and many electronic devices. ![]() The FET is a three-terminal device such as source, gate, and drain. FETs are widely used for switching and amplifying electronic signals in the electronic devices. MOSFET (also known as FET) is short for Metal Oxide Semiconductor Field Effect Transistor. This post will cover how to test a MOSFET transistor using an analog multimeter. ![]()
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