LCD-TV repair
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Originally posted by PeteS in CARemember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company. -
Re: LCD-TV repair
By following the traces from the HV inverter outputs I could see this was fed back to the inverter controller by some network. This could be the over voltage protection. Without the schematics this is going to be hard.
Attached is a picture of the inverter board.Comment
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Re: LCD-TV repair
Don't you have a datasheet for the inverter controller? They are usually obtainable by a minute (or less) of googling.Originally posted by PeteS in CARemember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.Comment
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Re: LCD-TV repair
Thanks guys, but of course I have the datasheet for the '9882 but no schematics of the inverter.Comment
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Re: LCD-TV repair
It's a good idea, but the load of the lamps seems to be purely capacitive and I don't know if this actually could be substituted by a resistive load. But one thing I might try is to power up another backlight (on another tv) with this inverter and see what happens. Then I could swap it all around and power the problematic panel with a known good inverter.Comment
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Re: LCD-TV repair
I had failed ccfls on au-optronics panel (L/G) panel would light up for 2 seconds then shut down.
I first found a bad mosfet on slave inverter. and repaired that and it was working( the inverter).
The best thing I did is take another inverter board (one piece) powered off of 24vdc.
I knew it was good and the backlights did the same thing (2 seconds to black).
I then pulled the panel apart and found 3 bad ccfls.
Took them from another panel and soldered them in (some solder in and some push in).
Then I replaced them all (used) for color match.Comment
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Re: LCD-TV repair
I had failed ccfls on au-optronics panel (L/G) panel would light up for 2 seconds then shut down.
I first found a bad mosfet on slave inverter. and repaired that and it was working( the inverter).
The best thing I did is take another inverter board (one piece) powered off of 24vdc.
I knew it was good and the backlights did the same thing (2 seconds to black).
I then pulled the panel apart and found 3 bad ccfls.
Took them from another panel and soldered them in (some solder in and some push in).
Then I replaced them all (used) for color match.Comment
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Re: LCD-TV repair
2.5kV is strike voltage, if that doesn't drop off at all before the inverter shuts down, then it's definitely failed CCFLs.Originally posted by PeteS in CARemember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.Comment
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Re: LCD-TV repair
I see no additional load on mains when inverter goes on, I would expect the power consumption to raise a bit if the CCFL were properly loading the inverter, but I cannot see this. Which also tells something is bad in the panel.
Is there any protection inside the panel, fuse or something that my go open if there's a CCFL failure?
It feels the HV goes into an open circuit.Comment
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Originally posted by PeteS in CARemember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.Comment
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Re: LCD-TV repair
Inside the panel, the connections to the lamps themselves.Originally posted by PeteS in CARemember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.Comment
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Re: LCD-TV repair
The panel has two HV wires, each on either side of the panel. I believe there are several CCFL or EEFL's connected in parallell, so why shouldn't a few light if one or more were bad? Or their wires were loose.
It looks like one of the inputs has been disconnected so none of the lamps has contact with the HV supply.
By the way, is it possible to make a capacitance measurement across the lamps?
After the easter holiday I'll try to take some close pictures of the panel assembly and see if any of you might have a good idea how to get into the lamp compartment.Last edited by PowerAmpFreak; 04-23-2011, 12:14 PM.Comment
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Re: LCD-TV repair
The panel has two HV wires, each on either side of the panel. I believe there are several CCFL or EEFL's connected in parallell, so why shouldn't a few light if one or more were bad? Or their wires were loose.
It looks like one of the inputs has been disconnected so none of the lamps has contact with the HV supply.
By the way, is it possible to make a capacitance measurement across the lamps?
After the easter holiday I'll try to take some close pictures of the panel assembly and see if any of you might have a good idea how to get into the lamp compartment.Whatever I do, I consider it a success, if in the end I am breathing, seeing, feeling and hearing!Comment
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