The circuit is shown in the attached picture. S is a button switch, press switch S when working, the power is turned on. The self-excited oscillating circuit composed of triode VT1, oscillating transformer T1 and resistor R1 starts to vibrate, the oscillating voltage is boosted by T1, and the diode VD1 rectifies the output of about 70V DC voltage. The voltage is divided into two paths, one of which charges the capacitor C1 through the resistor R2. The other path charges the capacitor C2 through the primary of the high-voltage pulse transformer 12 . When C1 is charged to about 30V, the divided voltage value of R2 and R1 triggers VD2 to turn on, providing a trigger pulse for the thyristor VS, and VS turns on. The voltage on the capacitor C2 is discharged through the anode, cathode of the thyristor tube, and the primary of the high-voltage pulse transformer T2, and the secondary of T2 generates a high-voltage discharge of about 10kV to the ground, and the discharge spark ignites the combustible gas. 
    Second, common troubleshooting  
    1. When switch S is pressed, the discharge spark is weak.  
    Maintenance: This phenomenon is often caused by insufficient battery capacity; in addition, there is poor circuit contact (such as battery circlips or switch contacts oxidized and corroded, resulting in poor contact). Just replace the battery or regrind the contacts.  
    2. Press switch S, there is no discharge spark.  
    Maintenance: In addition to the above reasons, the main reason is that the oscillator does not start to vibrate, and it is more common that the VT1 is broken or the T1 winding is open. If the T1 secondary has high voltage (tens of volts) output, it is common for C2, VS, VD2 to be damaged or the circuit to be de-soldered or soldered. It is also common for the T2 winding to open.
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