I
Ian Field
Guest
The CFL in the kitchen is left on 24/7 - sometimes they last a very long
time, this one not so much.
At first glance it looked as if the windings insulation on the feedback
toroid had incinerated, on closer examination; a capacitor next to it had
self destructed and sprayed its surroundings with ash.
The capacitor was on the negative end of the capacitive supply splitter in
the half-bridge.
All the semiconductors tested OK, but the 2 transistors were heat
discoloured.
The 4.7uF/400V electro read about half the rated capacitance and more than
the 40 Ohm that the Atlas ESR70+ is calibrated to.
The mains in RFI filter inductor had sacrificed itself to save the fusible
resistor.
The CFL was a Philips 18W.
time, this one not so much.
At first glance it looked as if the windings insulation on the feedback
toroid had incinerated, on closer examination; a capacitor next to it had
self destructed and sprayed its surroundings with ash.
The capacitor was on the negative end of the capacitive supply splitter in
the half-bridge.
All the semiconductors tested OK, but the 2 transistors were heat
discoloured.
The 4.7uF/400V electro read about half the rated capacitance and more than
the 40 Ohm that the Atlas ESR70+ is calibrated to.
The mains in RFI filter inductor had sacrificed itself to save the fusible
resistor.
The CFL was a Philips 18W.