Archive for the ‘How To Test Components’ Category

How to test a Diode on laptop.

This just a simple test to verify if the diode is working at all. Best to test components out of circuit. 1. Set the meter to test for ohms. Any range will work. 2. Connect the Positive probe to the cathode side of the diode and the Negative probe to the anode side of the […]

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How to perform quick check for bad caps.

1. Check with multimeter. 2. Touch with finger, if it feels hot then it’s shorted. 3. Test with crayon, crayon will melt when contact with shorted cap.

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Protected: Testing AC adapter with multimeter.

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How to test AO4407 MOSFET

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AC Adapter Doesn’t Work

Verify that the AC adapter brick is receiving power.  Shut down the computer and unplug the adapter from the system first and then from the power socket. Wait 5 seconds. Plug the adapter directly into the wall socket, bypassing surge protectors, UPS units, or extension cords. The adapter LED should produce a steady green light. […]

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How to test for shorted circuit

To test for shorts set your digital multimeter to resistance.  Connect the red probe to the positive pad on the systemboard and the black probe to the negative pad(ground). If it shows less than 0.5 ohms meaning there is a short in the circuit.

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How to locate short circuit.

Using a workbench power supply: You can use a regulated power supply to locate a shorted component.  Connect the negative output to the ground and positive to the fuse.  Slowly vary the output voltage and keep an eye on the current drawn. Soon as the current drawn about an amp or two, place your finger […]

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ESR Meter Table

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How to test your laptop AC adapter.

How can you tell if the AC adapter is supplying enough juice to your laptop? Well, You can test your adapter with a voltmeter. Here, I’ll show you how to test a HP 18.5v AC adapter with a digital voltmeter.  Most AC adapter has a label on them with their input and output specs. This […]

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Identify and test MOSFET – Video

Imagine the flow direction Drain to Source Set the meter to DIODE mode. To test N-Channel FETs put NEG(-) probe on pin 6 or 7 and the POS(+) probe on pin 2 or 3. If the FET is good you should get some value  between 100 to 500 or even higher, anything less than 100 […]

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