How to Test a Microwave Transformer

Suppose you ’ rhenium experiencing cold or lukewarm food from your microwave oven. In that case, you may need to know how to test a microwave transformer. Of course, flush the best microwave needs sustenance every once in a while, but testing a defective transformer is serious business. so, grab your rubber gloves, a screwdriver, and your multimeter, and we ’ ll walk you through troubleshooting a high-octane transformer .

  • The microwave transformer regulates the electric current and allows the microwaves magnetron to work.
  • Check the primary winding first, making sure you get a multimeter reading between 2.5 and 5 ohms.
  • Check both high and low-voltage secondary windings, looking for a multimeter reading of between 30 and 150 ohms in the high-voltage winding. Look for less than one ohm for the low-voltage winding.

Testing a Microwave Transformer

Tools : screwdriver, multimeter, rubber gloves
The microwave transformer is frequently a large, alloy, square-shaped unit of measurement that maintains the alternating stream of the magnetron and your world power beginning. The transformer has a primary hoist of thick wire, and below it sits low and high-octane junior-grade windings. The integrity of transformer windings is necessity for the system to work, so any breaks in the primary coil will cause a non-working microwave oven. This can cause issues like a microwave that trips the circuit breaker when the door opens.

Insider Tip
Given the complexity of electronics repair, don ’ deoxythymidine monophosphate hesitate to contact a local anesthetic repair shop class for higher-level trouble-shoot or repair service. even a defective high-voltage capacitor can contain enough energy to harm or kill an inexperienced repair person .




Microwaves are dangerous to work on if you aren ’ deoxythymidine monophosphate trained in dealing with an stallion high-octane circumference. In addition, as with any microwave oven animate, you run the hazard of severe electrical shock. therefore, if you feel at all diffident about testing the high-voltage transformer, reach out to a certified appliance animate technician before touching your fail high-voltage transformer. That said, most people should know how to reset a microwave without much risk .



Measure Primary Winding

Take your multimeter, set it to the Rx1 scale, and calibrate it. Place your meter leads on both diode terminals that lead to the primary coil hoist. You want an output electric potential read of fewer than 5 ohms .



Check Both Primary Winding Terminals

Use the digital multimeter to check both microwave diodes independently. Place your black conduct on the screw holes for the establish, and use the crimson terminal to measure each terminal. If you get a read on either, there is a short in the wind .



Check Secondary high-voltage Winding

Set your multimeter to the Rx10 scale and calibrate it. The high-voltage secondary wreathe is a single electrify from the back of the transformer. Ground one multimeter terminal and target the other in the junior-grade meandering. You want a read of between 35 and 180 ohm. If you get no read, the racing circuit is broken. If you get less than one ohm, there is a short .



Check Secondary low-tension Winding

Set your multimeter back to the Rx1 scale and calibrate it. Place both multimeter terminals across the low-tension secondary hoist. You want a reading of less than one ohm. If there ’ s no read, there is a break in the circuit. If your multimeter reads as grounded, your wire is shorted .



Reinstall or Replace

If your multimeter readings are reasonable, you can reinstall the high-voltage transformer. If not, you need to seek a substitute transformer or a refilling microwave.

Disconnected transformers and other electronic components can still hold an electric load, so take surely to leave your microwave unplugged for a minimum of 30 minutes before opening it up .
How many volts does a microwave transformer put out?
The electric potential of a microwave oven transformer and the voltage across the capacitor is about 2.1KV, or 2100 volts .
How do I know if my microwave is high-voltage?
Most consumer microwave ovens are high-voltage, so you do not want to touch the inside of your appliance until it is unplug and left to sit for no less than 30 minutes .
How do you diagnose a bad transformer?

There are some warning signs of a bad transformer. For exercise, your transformer may be bad if you notice a loud hum or burning smack while your microwave runs. It besides will cause your food to be cold .

STAT: A US Department of Energy review found that Americans in the East North Central US use their microwaves at least 25 % more than other Americans. ( source )