Cooker Oven PCB and Sensors , operation testing and common issues

In more modern ovens a PCB, Relays and sensors do the job of many of the selector switches, This enables very precise and economic control of the cavity heating saving energy and giving  better user experience.

Some of the less expensive parts can be easily tested and replaced on PCBs  but the more complex chips are not so easy to test find or replace and sometime its better to replace the PCB or it might be more cost effective to buy a replacement cooker oven depending on age of machine.

Some even give error codes it an attempt to help the engineer fault find but if the PCB is dead then this is not possible if you get error codes you will need manufacturer information to find the codes and solutions.

Common issues

PCB have many components and these can fail over time , it is possible for a failure in an oven component for example a shorted element or sensor to destroy board components so bare this in mind when doing your diagnostics on the machine.

A general rule is that if after testing all other components and eliminating them from diagnosis , and they all test good, then you can assume the PCB is faulty, this is an expensive call so you need to be sure.

Sensor are use to give the PCB accurate temperature measurements of the oven cavity to ensure precise cooking , these are usually NTC type temp sensors 

There are other methods to regulate the temperature but the most used today is the NTC sensor, the NTC sensor is a semi conductor and as the temperature in the oven cavity rises the resistance through the sensor decreases which is then used to control the on / off time cycling of the heating element.

NTC sensors monitor the cavity temperature and use this information to calculate if the heating time should be increased or decreased.

To test the sensor you need to set multimeter to ohms and check measurements against manufacturer documents. 

Its best to test the ntc at room temperature and measure against known good values but its possible to use hot water to test at a range of temperatures.

Common issues 

NTC can fail open circuit as well so will test OL on the multimeter so test for this , it may also trigger an error message depending on age and make - model.

if they test OL  or out of specification then replace them 

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Buy a good Multimeter on Ebay UK here