My 7 year old Samsung CCFL LCD lost the backlight. It would just blink for a moment after turning on.
I got to this forum via Google and after some tests and measurements suggested in this thread, the backlight started acting moody and I realized that diagnosing and repairing it wouldn't be an easy job.
But then an idea came to my mind: let's remove CCFL, put the LED strip in and voila - "LED" TV
Without any research, a couple of minutes later I had this on my table:
I replaced CCFLs with pieces of LED strip on the same place as CCFLs - 8 rows of them, all connected in series just like if I didn't cut it at all.
This is the end result.
With plastic sheets on top, there isn't too much difference when compared to CCFL. Maybe it's not as bright (but I don't have a reference as CCFLs wouldn't stay on), but it's quite good in reality.
One more...
I used existing CCFL holes for the power wires.
Test run proved the concept, but what about turning the LEDs on and off?
Well, it turned out to be very easy. I first removed HV transformers that used to power the tubes to avoid nasty surprises and used Dremel to cut the power to the entire CCFL HV section which is conveniently marked with a black line on the PCB.
Then I reused one of the MOSFETs to toggle the power - mainboard pulls the INV_ONOFF line high when powering on the TV, that's connected to the gate and controls the MOSFET. LEDs get power from permanent 13V line that's powerful enough to drive them. Voltage is dropped under 12V with 10 ohm/5 watt resistor which drops it to about 9-10 volts.
5 watts is too low and resistor quickly gets hot, but it's enough to prove that the entire thing works.
Close-up of the MOSFET. I cut it from the rest of the circuit as I experienced some weird problems.
Total cost: ~€20 for 6,5 meters of cool white LED strip and one high power resistor.
CCFLs are for sale if anyone needs them. I believe that they're OK and that the problem was on the board, but I'll give them for cheap since I can't confirm it. I'm in the EU but I can ship anywhere.
P.S. Only after I got it working, I searched and found out I'm not the only one with the idea. Why isn't this suggested more often?
I got to this forum via Google and after some tests and measurements suggested in this thread, the backlight started acting moody and I realized that diagnosing and repairing it wouldn't be an easy job.
But then an idea came to my mind: let's remove CCFL, put the LED strip in and voila - "LED" TV
Without any research, a couple of minutes later I had this on my table:
I replaced CCFLs with pieces of LED strip on the same place as CCFLs - 8 rows of them, all connected in series just like if I didn't cut it at all.
This is the end result.
With plastic sheets on top, there isn't too much difference when compared to CCFL. Maybe it's not as bright (but I don't have a reference as CCFLs wouldn't stay on), but it's quite good in reality.
One more...
I used existing CCFL holes for the power wires.
Test run proved the concept, but what about turning the LEDs on and off?
Well, it turned out to be very easy. I first removed HV transformers that used to power the tubes to avoid nasty surprises and used Dremel to cut the power to the entire CCFL HV section which is conveniently marked with a black line on the PCB.
Then I reused one of the MOSFETs to toggle the power - mainboard pulls the INV_ONOFF line high when powering on the TV, that's connected to the gate and controls the MOSFET. LEDs get power from permanent 13V line that's powerful enough to drive them. Voltage is dropped under 12V with 10 ohm/5 watt resistor which drops it to about 9-10 volts.
5 watts is too low and resistor quickly gets hot, but it's enough to prove that the entire thing works.
Close-up of the MOSFET. I cut it from the rest of the circuit as I experienced some weird problems.
Total cost: ~€20 for 6,5 meters of cool white LED strip and one high power resistor.
CCFLs are for sale if anyone needs them. I believe that they're OK and that the problem was on the board, but I'll give them for cheap since I can't confirm it. I'm in the EU but I can ship anywhere.
P.S. Only after I got it working, I searched and found out I'm not the only one with the idea. Why isn't this suggested more often?
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