Fly mosquito swatter repair / circuit analysis by ITTSB Blog

[Kiriakos GR]

Seems that many trying to repair or modify these mosquito swatters.
Unfortunately all information’s that few are spreading they are Utter garbage.

2SD0965 / 2SD965 transistor this is known for years, as this is main component for most basic camera flash unit.
This also called as strobo transistor because of it ability to oscillate and pushing out enormous for it size output of pulses.

Camera Flash units they do a very distinguish high pitch sound when they charge, this translates that frequency of pulses this is somewhere at the audible spectrum.

Transistor Oscillation frequency this is related to transformer that 2SD965 this driving.
Slightest problem at transformer coils impedance or condition of coil (partially shorted windings) this will cause oscillation to another higher frequency and HV circuitry it can not function properly.

Symptoms of damaged transformer this is Oscillation beyond 22 KHz and in my case this was at 500 KHz.
2SD965 this gets very hot in just 20 seconds, High voltage output instead of 3000V this become about 180V.
 

I also read Lots of Utter garbage as suggestions regarding diodes replacement parts.
RFC4K this is 2800 V RMS special HV diode, Peak Reverse Voltage 4000 V.
Nothing regular can replace a special diode with 6V Forward voltage.

Bellow there is several pictures’ of my own adventure,  and my advice if you need to repair such a thing,  this is use a new transistor and if this fail to work, then trash the all thing, because there is no available transformers’ for it.