Faulty MQ2 Sensor In Gas Detector
I received a gas detector for repair, the complaint is: after few minutes the beeper will sound but the gas is not interrupted. After connecting the detector, it takes about 2 minutes to calibrate; next it will enter in detection mode. When detect the gas leakage, the gas is interrupted for safety.
In the above picture you can see the gas detector, no name.
Four screws and the detector were opened. Take a look at the circuit board below:
I started to check the surrounding components, and everything was ok. Next I searched on the internet for more details about MQ2 sensor.
According to the datasheet, the sensor should need 5V ± 0.1 to work and the heater resistance is about 33 Ohm-see the photo below:
You can check out the datasheet here. When I measured the voltage at the sensor, it was 4.9 V, so it was good, but when I checked with ohmmeter the heater resistance, it gave me 0 ohm. Yes, I found the culprit!
Next I bought the sensor and replaced it and the Gas detector came back to life again.
This article was prepared for you by Mihai Mazarus from Brasov Romania. He works in a copyshop and his hobby is electronics repair.
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