How to solve the problem of undervoltage in Wanke electromagnetic furnace?
The heating wire disc removed, measuring second feet (ICIA) comparator output to ground is low, but the fault is not excluded should check the comparator peripheral component resistance R23, R3, resistance is variable, or open circuit, capacitor C9, C10 leakage, or failure. In addition, maintenance should pay attention to: resistance R24 (240K, /2W), R27 (240K, /2W), variable or open circuit. When the resistance value is about 260K, the zener diode Z3 capacitor C19 leakage occurs, "alarm heating" fault occurs. When the resistance R24 and R27 change to infinity, the zener diode Z3 and the capacitor C9 breakdown lead to "no alarm, no heating" fault. After replacing the damaged components, the machine will be restored to normal. (in maintenance, attention should be paid to the analysis of the faults, respectively)
When the power is on standby, the measuring comparator (ICIA) is fourth feet, the input of the inverting input is normal to the earth, the voltage of the +4V is fifth, the input to the ground is +4.1V, the voltage is normal, and the output voltage of the second pin is normal to the ground, and the +5V voltage is normal. Remove the heating coil, measure the comparator (ICIA), the second pin output to the ground, the +0.2V voltage is normal, when the 0 voltage. Measure (ICIA) fifth pin input to ground 0 voltage. Causes the comparator (ICIA) to turn over rapidly, and the second pin output is changed from high to low. For high level, the comparator (ICIA) is damaged and the damaged (ICIA) is replaced and the machine returns to normal.
Test the filter capacitor C2 to +305V voltage is normal, when the voltage is low, or the 0 voltage, then the filter capacitor C2 (5 F/275V), when the IGBT failure of 0 C collector voltage, inductance coil L1 off, open or weld, leading to IGBT collector without voltage and the emergence of "police report no heating fault, or lead to the breakdown of IGBT damage. Replace damaged components, re weld and return the machine to normal.
