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Head scratching fault.

dmmarchy

Jun 7, 2013
2
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Jun 7, 2013
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Hi I have a Cheap Technika 22" lcd tv.. I have a Passion for fixing things etc and cannot fathom out latest problem.. TV turns on, very dim screen almost black. but you can just make out menu etc. I was told to check for blown caps (ie bulging heads ) these all seem okay. I was then told to change the inverter card. which i did and still the same.. Odd thing is when i hold down display button on the remote the screen appears for a couple of seconds, then goes again until i press display button again.. 2 seconds then off... any pointers or clues would be much appreciated .. I know its only a cheap telly but love tinkering and fixing things .( hate to see waste electrical gear in this throwaway society ) Many thanks.
 

GreenGiant

Feb 9, 2012
842
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Feb 9, 2012
Messages
842
its possible its a setting, the Backlight setting to be precise, try increasing this.

Measure the voltages to the inverter board, there may be something faulty there.
 

dmmarchy

Jun 7, 2013
2
Joined
Jun 7, 2013
Messages
2
Many thanks for your replies .. Ive been through all the settings and all set correctly. ( was quite tricky had to keep pressing remote display to see screen then 3 secs before it went off. took me about half a hour ! ) I purchased the inverter board new. off Ebay. Could it be the infra red detector ? If i constantly keep pressing the display button screen stays on. but if i stop 3 secnods later goes back to black screen ? Many thank guys.
 

davenn

Moderator
Sep 5, 2009
14,275
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Sep 5, 2009
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14,275
I agree with green giant and sheldon

the chances are its either the inverter board or the CCFL tube that the inverter board drives
I have seen very few CCFL failures, 99% of the time its the inverter board

Dave
 

KrisBlueNZ

Sadly passed away in 2015
Nov 28, 2011
8,393
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Nov 28, 2011
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8,393
It seems odd that the backlight comes on for a few seconds then turns off, with a new inverter board. I guess it could be a problem with the CCFL tube that causes the inverter to detect a problem and shut down... Have you checked for compromised insulation on the CCFL connections? Run it face down in a dark room and look for arcing or corona on the wiring to the CCFL tubes? Also, check the enable signal from the main board to the inverter and/or force the inverter's enable input active.

Those are just suggesitons. I have little experience with LCD TVs. YMMV. Good luck!
 
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