another quick question, I found a bad .1uf 50v electrolytic, I cant seem to find an electrolytic replacement, I have several 104 ceramic and film caps, but I cant find the voltage ratings for them, I have a few .1 uf 100v electrolytic as well but they all test pretty high on the esr meter (I'm not sure if this is normal or not)? which would be the most suitable?
I went ahead and replaced it with the largest size film cap of that value, and it now works, well sort of, I now am able to turn on the tv and if I stand to the side and push the menu button I can see the menu but I have no backlight, for my next question what is the more common failure the bulbs or the inverter circuit? It does start to light for about 2 seconds from the bottom then blinks off.
update> I went ahead and opened up the panel exposing the inverter board, someone has been here before me as the lead to one of the cfl's was unhooked and the board has seen better days, the second set up was unhooked, but looking at the state of the board I was wondering what caused this to fail? It obviously got quite hot as some of the components are melted. the transformers themselves ohm out as ok but the control circuits are going to need some work.
I tried to resolder the existing components but alas still no backlight, the mosfets that were melted off the board are no longer made, so I may try to get the next closest chip or if I can find a good deal on a replacement board I may have to go that route.
I'm not to familiar with these circuits it tries to power up for about 3 seconds then shuts down I assume something is shorted on the board and the control chip is shutting off the circuit is there a way to test the mosfets with an ohm meter? they are a
https://www.fairchildsemi.com/ds/FD/FDS6990A.pdf
I went through and metered all the mosfet legs and found the two that were melted were shorted out, do you think this was caused by the unhooked bulb or did the repair tech unhook the bulb because the mosfets were bad when they worked on it? All the fuses are intact so I am still wondering what caused these two to have a meltdown. how important are the tolerances on these to the micro controller as the replacement chips that are in stock have slightly different capacitance values?