Connecting two CCFL lamps in parallel

[Timescope]

Hi Everyone,

After hours of troubleshooting the backlight inverter of an LG 42" LCD tv model 42LK450, I have finally found the problem to be a defective CCFL lamp after removing the fragile liquid crystal glass screen.

Replacements are not sold here so I obtained two 42" broken screens but these use 20 thinner lamps (about 3.3mm diameter) and the LG uses 10 lamps 4mm diameter.

The difference in characteristics of the thinner lamp is detected by the inverter circuit and it shuts down.

I am looking for a method to connect two of the thinner lamps in parallel. I tried a direct parallel connection but the first lamp to strike took all the voltage.

Would ballast capacitors work ?

Any ideas would be appreciated.

Thanks,
Timescope

 

[Nigel Goodwin]

CCFL's in TV's are normally connected in series pairs.

 

[Timescope]

Thanks, I will try them in series.

One end of the lamps are soldered to a grounded copper strip and the other end plugs into a socket connected to the HV winding of the inverter transformers as shown in the attached images.

Timescope