Schematic and troubleshooting of LD 4000 FL ballast

[krzychb]

Hello everybody and here is my first post

Thanks to great blog by Pavel Ruzicka I have managed to repair two faulty electronic ballasts of LD 4000 fluorescent lamps by a German company Elektra. I have seven of them used every day since more than 12 years. Two failed out of seven over 12 years seemed to me a reasonable reliability to invest some time for repair.



You will find schematic of ballast and description of repair in my repository.

Below is a nice waveform of ballast starting up.  I consider it as an EKG of FL brought back to life



If you have such lamp and it happens to be faulty, do not throw it away because it is robust, nicely designed and therefore fun to fix.

Krzysztof