Mosquito Killer Racket Repaired For Low Sparking
Another racket repaired for above stated problem. When press the button and touch the net it gives very low spark that means no sufficient power is present on the net. Because of low killing power mosquitoes are escape from the net. So I have opened the racket for repair. On physical inspection there is no visible sign of burnt out or broken parts.
As per my previous experience I doubt on Big Capacitor that is 223j2KV.(Most of the time it degrades if racket is in frequently in use for year or two because here we use it for high current spark by shorting two legs of the capacitor).
So on doubt I replaced the Capacitor for further testing. (Always remove the Battery while you are replacing any parts of the PCB and do not forget to discharge the capacitors before working on them).
After replacing the capacitor I have connected the battery and for testing I pushed the button and shorted the net with using screwdriver still the same low spark problem. Now it is time to test all the components on high current oscillator side.
Tested 3 diodes near capacitor marked with RFC4K all are ok. Tested oscillator transformer that is also in normal reading.
Now what remains is Transistor. So I removed the transistor (SD965 NPN) for testing. On testing I did not found any leakage or Shorting but I noticed the reading pattern.
Here reading is bit confusing it should be same. I am not having this transistor with me right now hence I arranged one transistor form my storage where I salveged parts form highly damaged non repaired equipments. so arranged D882 NPN transistor.
Here are some transistors which are commonly used in this type of rackets 2SD965, D882, 8050, BEL188, 2N2222, SL100, BC182, BC338……..
So I have replaced the transistor for the testing. On testing I found loud bang noise of the spark. Tested for few sparks & this is how I revived this racket and now it is time for re assembling……. but suddenly I have one question in my mind about Reading of the Bad transistor so decide to test the reading of this replaced transistor also.
So I removed D882 Transistor from the circuit.
And here are the readings of D882 NPN Transistor.
After testing & replacing the transistor I reassembled the racket. Now it is ready for the attack…………
This article was prepared for you by Yogesh Panchal who works as a Computer Hardware Engineer in Mumbai India.
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Note: You can check his previous repair articles in the link below: