 Replacing blown backlight drivers
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Conundrum
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Sun Nov 28 2010, 12:20AM
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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.
Just started on fixing some of my stubborn collection of broken TVs.
This one is a 23" LCD with composite and VGA in which needs 24V at 5A (!) to drive the backlights and mainboard.
I briefly got it to power up but one tube was clearly out and it almost immediately shut down.
Yet all 6 tubes test fine on a spare inverter of the CCFL caselight variety at much reduced brightness, the board is a LC230W01-A2.
The TV seems to run fine with the board out and I confirmed that the fuse had blown.. bypassing it only proved that the current draw was excessive and in all likelihood one or more of the twelve HV transformers have shorted turns.
i was thinking along the lines of scratch building a replacement inverter PCB using a salvaged known good transformer from a 32" TV with a single output which is connected to each tube with a series capacitor to spread the load evenly.
 but still pretty expensive and i need to buy a power supply as well.
What this particular TV does have is a lot of space inside and a metal chassis ideal for mounting a laptop or other motherboard to turn it into an eeepc clone with a much larger screen...
ZVS maybe?
any ideas appreciated.
-A
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Registered Member #56
Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2445
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You could probably get away with a single larger transformer and a number of series caps, but it seems like for the £25 you might be better off just buying the inverter board.
However... if you are bored and not concerned with damaging the tubes I would recommend using a half bridge feeding an 'inverter microwave' transformer. I doubt that a TV flyback will have the current to power all of the tubes in parallel without a rewind, but it would be worth a shot as well.
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