Failed Secondary Filter Capacitors (bulging/high ESR) or Shorted Output Diode Secondary Output / Cold Side Backlight flashes briefly then goes out
Cold or cracked solder joints around high-heat components like diodes, transformers, and transistors. Step 2: Checking the Primary Voltage Rail Set your multimeter to DC Voltage (1000V range).
: AC mains (220V–240V) enters through a fuse (usually 10A–15A) and a varistor for surge protection. chk-v9.04g circuit diagram
The diagram reveals an auxiliary winding on the transformer that powers the PWM controller after startup. A startup resistor (typically 150kΩ – 470kΩ, 2W) from the bulk capacitor initially charges the VCC capacitor. If this resistor fails open, the board will "click" repeatedly as the IC tries to start and fails.
Check the feedback loop (TL431 and Optocoupler) if your output voltages are present but consistently too high or too low. The diagram reveals an auxiliary winding on the
To prevent the unit from blowing up or melting, the board actively samples grid voltage, coil current, and temperature using operational amplifiers (like an LM339 quad-comparator) and thermistors positioned under the glass and directly on the IGBT heat sink. 🛠️ Common Faults and Troubleshooting
Degradation of the primary electrolytic smoothing capacitors (C1/C2), leading to an excessive voltage ripple that triggers the MCU’s Brown-Out Reset (BOR). Check the feedback loop (TL431 and Optocoupler) if
Converts incoming 220V AC into pulsing DC power. This block works alongside a large 5µF filter capacitor to deliver a stable ~310V DC rail dedicated to the main induction coil induction heating loop. 2. The LC Resonant Tank and IGBT Drive