Another glitch... The backlight on my 3 year old TV is acting up. After about 4 minutes, the screen loses backlight. Image is there, audio is there, all controls are there.
Let off for a while and same story a few minutes after turning on, all CCFLs go off, not like some stay on and some do not.
That tells me the CCFL lamps are good. -Are they ?
That tells me the inverter works. -Does it ?
That tells me the problem is after something gets warm. Is it ?
Of course, unable to find a schematic for this TV : Trutech PM1919B
Inspecting the circuitry; a TL494c PWM IC drives a couple of dual mosfets 4511GD to two pairs of CCFL tubes.
Connected other lamps to it; they work.
Searched for 1/8" x 1/8" surface mount LED strips replacement instead of CCFL; did not find; and suspect that if I find them; would cost more than the TV. So here we go again on the ranting... Planned obsolescence. Keep landfills well fed. Buy more chinese crap, as there is no other source.
Somewhere I read that if the current in all the lamps is not 'balanced' , the circuit may shut down itself. It may be right; never seen a backlight set partially off --- Brilliant !
If that is the case, you are left with nothing instead of one or two lamps extinguished. How to disable the 'unbalance' shutoff ?
Where would you continue troubleshooting with no schematic ?
Miguel
