Quote:
Originally Posted by ronl
im hopping it is the power supply since switching the 2 cables resulted in the problem changing sides-points to supply problem and not load side. the set fired up today with orginal problem-works well for about 20 min,then 1 side dims.might try cold spary. im gonna measure each pin when it is working well and if i cant find schematic of power supply,then i might diy a seperate supply for backlites.just wondering if its ac or dc or mixed. should i measure with a dc scope incase there is a signal or just a plain voltmeter?also, im wondering what controls the brighness of these lcd flat panels?is it the brightness of the backlight? how about modern video projectors? is the brightness controlled by bulb brightness?from what i can figure out since a schematic seems rare to find is this is the case. am i correct?
thanks for reading this thread.
RonL
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Usually the backlights on these LCD TVs use what's called a Cold Cathode Florescent Light (CCFL) and those actually use an inverter to convert the DC Current from the electronics to the AC Current that the bulbs need and if those inverters go out then your CCFLs go out or don't work right because the CCFLs require AC Current to run which is acquired through the inverters, I would check the inverter circuitry first to make sure it hasn't failed.