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daewoo lcd tv

 
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billkell
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PostPosted: Tue Sep 28, 2010 10:23 am    Post subject: daewoo lcd tv Reply with quote

hello all
i have a daewoo lcd tv it all works but no backlight what do i need to check all the caps look ok mod DLV-32C7SMB
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Pentode



Joined: 30 Oct 2007
Posts: 85
Location: Nr. Manchester (UK)

PostPosted: Thu Sep 30, 2010 12:09 am    Post subject: Reply with quote

You'll find it's either the backlights themselves (known as CCFL's - Cold Cathode Fluorescent Lamps)... these are very, very fragile about the thickness of a knitting needle and the length of the screen or it'll be the inverter board itself.

Best thing to do is to Google 'LCD Inverters and back lights'

You gave very little info, back lights don't just 'not work' (unless you give the screen a fair knock), the first sign of deterioration is the 'White's start to discolour and the picture become tinted and becoming dull... then they start to flicker AND finally expire.

The inverter module that drives these can give the same effect but they can and do go all at once without any warning... so it's worth considering how the fault developed. To effect a 100% reliable repair it's as well to change them both, the backlights and the inverter board.

Changing backlights need time and patience as well as a steady hand, some can be quite a pain... guess the workshop routine would be to fit a new display and let the customer pay.

Dave
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PostPosted: Sat Oct 02, 2010 5:38 pm    Post subject: Reply with quote

thanks mate but its not the back light or inverter
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train123_not logged on
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PostPosted: Mon Oct 04, 2010 7:56 pm    Post subject: Reply with quote

Your problem is still related to the backlight section. Start by checking the power supply to the Inverter. I haven't worked on that brand but it'll be something like 24 volts. You can then also check to see if the "on" line is being sent to the Inverter board from the processor board / power supply (a wild guess would be in the +5 to +8 volt range). Depending on what you find with these two voltages, you can isolate the problem to the power supply, inverter board or lamps.
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PostPosted: Tue Oct 05, 2010 1:15 pm    Post subject: Reply with quote

thanks i will check 5+ volts and see what i find
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