 Hacking TV/monitor backlight drivers
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Conundrum
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Tue Jan 03 2012, 08:41PM
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Registered Member #96
Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4061
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Hi all.
Has anyone else run into the infamous "no backlight" fault on TFT TVs and monitors?
It appears that the expensive hybrid IC on the board fails, causing the power supply to "chirrup" and then the 5V appears for the TFT and panel lights.
This is on a Dell 19" with DVI-D which none of my other monitors have..
I temporarily hooked up a dual output piezo CCFL driver from a Sony laptop which lights up the tubes but it isn't happy and "ghosts" if the screen is touched.
Is this likely to be a grounding issue?
My plan is with the larger units needing 8 or 16 outputs, use an array of saturable reactors to control each tube and drive them all from a common +/- HV supply with the SR's in series with the +HV supply, probably salvaged toroidals.
The reason for this is that each tube current would otherwise depend on the series capacitance and tube temperature so instability and a cooked tube would result.
It looks like this approach is used on some commercial supplies so I may be on the right track.
As for driving the single or paired HV transformers a simple MOSFET based ZVS would do the job and we all know how to build these 
Thanks!
-A
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