I have the symptom where the backlight is cycling. I have read other threads about various problems with transformers and MOSFETs and have a few questions.
A bit of background on the TV is that it was used very little and that is why I was considering trying to repair it. It was plugged in and not being used when a nearby lightning strike took out a 60" plasma, cable box, receiver, and other small devices (+ $2K in lost electronics). I suspect that this strike also damaged this TV but I cannot determine how badly. It was several days later that the backlight started cycling and it was not immediately after the strike. I have heard there can be a delay between the strike and apparent damage so that is a possibility. I also realize there is a possibility that other boards are damaged and that will not be discovered until the inverter/backlights are addressed.
The TV does turn on, the backlight cycles on and off. I can hit the menu button on the remote and see that the menu is displayed. At this point it seems to be an inverter/backlight only issue (maybe).
I have little knowledge in debugging electronics so I am looking for a few pointers to debug.
A few of the questions that I have are:
1) When I disconnect the Inverter Board (BN44-00264B) from the logic board, should the backlight come on and stay on? It does come on briefly but then cycles on and off thereafter.
2) Reading other posts on the forum It seems that transformers can be bad. There are no visible signs over overheating. I would like to know if I can test them with a multimeter while they are in-circuit or do they need to be desoldered and removed to test each one? I have the same question for the MOSFETs.
3) I have also read on other posts that it is possible that there could be problems with the backlight bulbs where they are drawing too much current and this is what causes the inverter board to go into an overcurrent mode. Is there and easy way to rule out the bulbs with a meter/power supply or is this a visual inspection only?
I have visually inspected all the capacitors on the inverter board and they look OK. I also tested all of the diodes and they are also all OK. The two fuses are Ok.
Based on the above, and given the age of the TV and symptoms, would it be best to:
1) Attempt to debug the inverter board and/or bulbs?
2) Roll the dice and buy a refurbished inverter for $50 off of eBay and hope that the bulbs are not the problem?
3) Take the TV to the electronics recycler and call it a day?
I am a hobbyist interesting in debugging but I can see that pulling all of the devices (transformers, MOSFETs, capacitors) would be quite an investment of time (since I rarely do it). If the symptoms suggest that buying the refurb inverter board is the best course to take to save time please let me know.
Any advice would be appreciated.
Thanks.
Heath
A bit of background on the TV is that it was used very little and that is why I was considering trying to repair it. It was plugged in and not being used when a nearby lightning strike took out a 60" plasma, cable box, receiver, and other small devices (+ $2K in lost electronics). I suspect that this strike also damaged this TV but I cannot determine how badly. It was several days later that the backlight started cycling and it was not immediately after the strike. I have heard there can be a delay between the strike and apparent damage so that is a possibility. I also realize there is a possibility that other boards are damaged and that will not be discovered until the inverter/backlights are addressed.
The TV does turn on, the backlight cycles on and off. I can hit the menu button on the remote and see that the menu is displayed. At this point it seems to be an inverter/backlight only issue (maybe).
I have little knowledge in debugging electronics so I am looking for a few pointers to debug.
A few of the questions that I have are:
1) When I disconnect the Inverter Board (BN44-00264B) from the logic board, should the backlight come on and stay on? It does come on briefly but then cycles on and off thereafter.
2) Reading other posts on the forum It seems that transformers can be bad. There are no visible signs over overheating. I would like to know if I can test them with a multimeter while they are in-circuit or do they need to be desoldered and removed to test each one? I have the same question for the MOSFETs.
3) I have also read on other posts that it is possible that there could be problems with the backlight bulbs where they are drawing too much current and this is what causes the inverter board to go into an overcurrent mode. Is there and easy way to rule out the bulbs with a meter/power supply or is this a visual inspection only?
I have visually inspected all the capacitors on the inverter board and they look OK. I also tested all of the diodes and they are also all OK. The two fuses are Ok.
Based on the above, and given the age of the TV and symptoms, would it be best to:
1) Attempt to debug the inverter board and/or bulbs?
2) Roll the dice and buy a refurbished inverter for $50 off of eBay and hope that the bulbs are not the problem?
3) Take the TV to the electronics recycler and call it a day?
I am a hobbyist interesting in debugging but I can see that pulling all of the devices (transformers, MOSFETs, capacitors) would be quite an investment of time (since I rarely do it). If the symptoms suggest that buying the refurb inverter board is the best course to take to save time please let me know.
Any advice would be appreciated.
Thanks.
Heath
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