Electrical ballast Repair

[Bskitter]

Hello Guys, I am trying to repair a ballast circuit for a small floresent blub.

I placed a bulb in which was the incorrect value and it damaged the ciruict it somehow.

One day I get home and I could smell some magic smoke was escaping. I now found the correct type of bulb and the light is not constant but more like a warping effect.

I have tested both transistors and the large capacitor, they are fine.

Can one guide me to what could be wrong ?

I do not have a schematic but here is a photo of the blub if that helps

[Armadillo]

Did you twist in the tube correctly.
Only 8 diodes and 7 resistors. So just use a multimeter to measure and check those to be within normal range.

[eKretz]

I've repaired a fair number of similar ballasts - this is one of those compact fluorescents with the U-bulb isn't it? Usually on the ones I've repaired,  these fail at a resistor or diode in the circuit path near the transistor.

[Cyberdragon]

  One of those diodes is missing it's polarity (cathode) band! Check those two resistors next to the large green capacitor, I see smudges which might be burn marks.

[Armadillo]

One of those diodes is missing it's polarity (cathode) band! Check those two resistors next to the large green capacitor, I see smudges which might be burn marks.

You need to desolder it out from the circuit to confirm it again.
For resistors, check resistance against resistor color band. If cannot get, desolder from the circuit and measure again.
Ascertain before change policy.

[bktemp]

One of those diodes is missing it's polarity (cathode) band!

It could be the DIAC used for starting the oscillator. This type of diode will show as open in both directions when checked with the diode test function of a DMM.

If all diodes are ok, it could also be the foil capacitors being damaged by the wrong load.