â‘ Check whether the tension spring of the relay falls off; whether the contacts are "burnt out" and stick together; whether the mercury column wire in the electrical contact thermometer is interrupted; whether the wire connecting the thermometer on the top of the drying oven is disconnected, and whether the terminal is in poor contact. â‘¡Check the resistance R with a multimeter. Whether R is open internally or the solder joint is unsoldered; measure whether the 7 pin (grid) of the electron tube has a voltage of about 20V; check whether the 7 pin of the tube base is in good contact. If after the above inspection and repair, the fault is still not eliminated, you can use your hand to repeatedly turn on and off the power switch. Observe whether the relay contact can be flexibly released when the switch is closed. If it cannot be flexibly released, it may be that the anti-tension spring is heated for a long time and relaxes Loss of elasticity causes the moving contact to not return flexibly after the relay coil is de-energized. In this case, you can turn off the power, remove the spring, and cut out a section to try; if not, you can replace it with a new spring with a large elasticity to solve this problem. 3. The temperature in the drying oven has not reached the set value, and the power is turned off. When the drying box is working normally, the resistance wire R in the box and the power on and off are controlled by the electronic relay. However, when a component of the circuit fails (such as a resistor R open circuit), it will cause the input power supply to lose control, causing the temperature to rise continuously, thereby causing a greater failure. To this end, a set of "temperature safety controller" KK is connected in series in the power supply line. When the circuit is out of control and the temperature exceeds the limit, the KK contact is automatically separated to cut off the power supply of the drying box, thereby ensuring the safety of the instrument . If the temperature in the drying oven does not reach the set baking test value, the power is disconnected. The reason may be that the position of the temperature adjustment bolt on the temperature safety controller moves, so that the glass rod moves into the copper tube prematurely, and the The two energized contacts are separated. Solution: First set the electric contact thermometer KK at 150 c (=, and then heat the drying oven, and wait for the temperature in the oven to rise to 150 c (=, adjust the adjustment bolt of KK to separate the two energized contacts. In addition, the fuse blown during the heating process of the fuse RD will also cause the above-mentioned failure, which cannot be ignored. Analysis and elimination of other faults 1. The temperature of the drying oven is normal, and the fan does not rotate. The temperature of the drying oven is normal, indicating that the mains input is normal. If the fan does not rotate, you should search for the components and parts related to the motor. First check whether the fuse of the fuse RD is blown and whether the connecting wire is open; the capacitor C :, whether the terminals of the motor are loose or unsoldered, then remove the lead of one end of the capacitor from the terminal of the motor, use a multimeter to check whether there is leakage or breakdown. If after the above inspection, the fault is still not eliminated, it may be that the motor is faulty, remove the motor and check for repair or replacement. 2. The relay contacts cannot be closed normally, and a continuous "click" noise is emitted. This phenomenon is mostly caused by the failure of capacitor C (leakage or breakdown). The reason is that after the capacitor fails, the filtering effect on the screen current of the tube is lost, and the current through the relay coil is no longer a smooth pulsating direct current, but a pulse current that is positive and negative. That is, when the transformer secondary output is positive half cycle, the relay coil is energized to make the moving contact pull in; when the transformer secondary output is negative half cycle, the relay coil is de-energized, the armature is demagnetized, and the moving contact returns under the action of the spring . When the secondary output of the transformer secondary exchanges for the second positive half cycle, the relay coil is energized and the moving contacts are attracted. The secondary voltage of the transformer changes so cyclically, causing the relay contacts to continuously pull in and release, making a continuous "click" sound. When overhauling, you should first check whether the capacitor connection is open or unsoldered, and then replace a capacitor with the same voltage and capacity. In addition, if the newly purchased drying oven or the newly replaced relay has a similar failure, it may be that the spring tension on the relay is too tight, and the adjustment bolts can be appropriately loosened to solve. Pet Training & Behavior Products,Dog Training & Behaviour Aids,Dog Training Equipment Items,Dog Training Behavior Ningbo Yinzhou Hengxi Winbate Household Product Manufacturer , https://www.nbwinbate.com