1. The power indication is normal, but the temperature controller has no screen display. This fault is mostly caused by the voltage stabilizer (7805 or 7812) on the temperature controller, which generates heat in the process of long-time use and leads to the breakpoint of solder joints. Sometimes, it is caused by the phenomenon of virtual welding when leaving the factory, which can be mainly resoldered.
2. The temperature controller shows normal, metal sleeve thermometer, Marine thermometer, v-type thermometer and copper sleeve thermometer, but they cannot be added. Generally, the heating elements are damaged. If the relay is good, the relay drive element (9013) is bad. For solid state relay, it is easy to be damaged, and for bidirectional SCR, the phenomenon of burning loss is less.
3, the temperature controller shows the temperature is much higher than or far below the actual temperature, this phenomenon is generally the temperature sensor damage, replacement can be.
4, the temperature controller appears 999 or 000 beat and alarm output, laser rangefinder, digital oscilloscope, grounding resistance tester, anemometer this phenomenon for the sensor circuit, such as LLL or half 000, this phenomenon for the sensor short circuit, can be replaced.