Microwave making noise in San Jose, CA

Issue description:

Today, almost every home has a microwave, which is used to heat food, prepare hot sandwiches for breakfast, and warm up milk formulas for young children. Microwave ovens emit hum and slight noise during operation. But when the noise gets too strong, it’s a signal to the users that something is going wrong. Let's figure out why the microwave can hum a lot when it works.

There can be many reasons why the microwave starts to hum. Regardless of the level of complexity of the breakdown, the device needs to be repaired or serviced as quickly as possible. If this is not done, even a small problem can cause serious problems and increase the cost of repairs.

Tray slips

This is most often due to insufficient maintenance. Namely: food debris accumulates under the tray, the plate wedges. As a result, the engine is under heavy loads and can slip. This leads to overheating and wear. The microwave should be cleaned.

If this does not work, you will have to check the condition of the drive system. To do this, remove the casing and the lower part of the pallet.

Broken fan

Most often this happens due to wear of the sleeve. This happens pretty quickly in inexpensive microwaves. This problem manifests itself even more in models that have a common sump and fan motor. The system of blowing and air circulation must be checked.

Problems of the magnetron

When the emitting lamp fails completely, the microwave makes a loud hum and does not heat up. Damage to a magnetron is dangerous. Microwaves with this problem often spark. The magnetron should be checked.

The emitter is usually not repairable. It is changed entirely. You can buy a new magnetron online. However, its cost is often comparable to that of a new microwave. Therefore, if testing has shown a breakdown, it is worth considering whether repairs need to be done. After all, buying a new microwave is guaranteed to exclude possible reasons for the failure of the magnetron.

Breakdown of a capacitor or changing its parameters

In this case, the microwave makes strange sounds. You can check the capacity of this part using a conventional multimeter. But before testing, the capacitor must be completely discharged. If the case does not ring when measuring the parameters, it means that you need to change this part.

Failure of the high-voltage diode

With such a breakdown, the microwave emits squeaks, whistles and heats up the heat exchanger. The repair is simple: the diode is checked with a multimeter and, if necessary, replaced. If the part is working properly, it does not ring at 9V.

How to diagnose

An initial microwave check can be considered standard. The device is partially disassembled. To do this, the screws on the back cover are unscrewed, and the casing is removed. The insides of the device are carefully examined. Searches for reflow zones, parts and contact areas with carbon deposits. The soldering points of the wires and the condition of the latter are very carefully examined.

Then the main fuse is examined. Its body is transparent. If the fuse is triggered, the broken thread inside will be visible visually. The part needs to be replaced. But if, when turned on, the fuse blows again, testing continues.

For the further diagnostic process, you will need a tester. Check all the details on the magnetron board. The call can be made without soldering the elements. If units with parameters inappropriate to the schematic diagram are found, they are replaced. The testing of the board ends by checking the thermal fuse. In a normal state, its resistance should be equal to zero.

You will not be able to check the power diode with home appliances. It is included in the 220V network. One end directly to the power wire, the other to the other with a tester connected in series. If the latter shows voltage at one or the other position of the diode, then it is working. Otherwise, the part must be replaced.