TV CCFL circuits in general

[romansroad]

I just parted out an LG 46" 1080, and peeked inside the lamp section....yikes! 16 horizontal ccfls with their HV caps on the end of the boards. Looked back at the inverter stage and noted the 1200v at 140mA output. Since this unit only had 2 HV leads and 2 inverter transformers, how is the voltage supplied/distributed? The LCD monitors usually have one xformer per tube, and all the complex feedback to the logic board. Do the LCD TV's have similar set ups? If one tube fails, does it shut down like the monitors do?

[alexanna]

Re: TV CCFL circuits in general

read post #33
https://www.badcaps.net/forum/showth...t=12151&page=2
Al.
Well that my not be what you ask but it's intrestring

[romansroad]

Re: TV CCFL circuits in general

Thanks, and that helps. I suppose in this 46" TV, then we're running 8 ccfls from one xformer, using a sort of series circuit and one that provides feedback to shutdown if needed. Interesting. I'll see if Electrotanya has the schematic, just to satisfy my curiosity.

[PlainBill]

Re: TV CCFL circuits in general

Thanks, and that helps. I suppose in this 46" TV, then we're running 8 ccfls from one xformer, using a sort of series circuit and one that provides feedback to shutdown if needed. Interesting. I'll see if Electrotanya has the schematic, just to satisfy my curiosity.

Very unlikely it's serial, much more likely that they are in parallel.

PlainBill

[romansroad]

Re: TV CCFL circuits in general

my mistake...I meant to say parallel. Still wondering how they maintain a complex feedback of individual lamps in such a circuit with only two big sources of HV. Just looked at a post with multiple individual xformers feeding each tube. That I can see, the other setup seems very ingenious and cost effective. Granted, this LG I was parting out is just a year old...

[Th3_uN1Qu3]

Re: TV CCFL circuits in general

They probably have some sort of ballast built into the lamps themselves, or onto the board, before they sum into the transformer.