I have a question for you as I am in a quandry, I will explain,
I have 2 boards on the desk in front of me now, both dells, E173fpf + E153fpf.
Both monitors were totaly dead before removing the said boards, they are the 3 in 1 type inverter + psu + video on the 1 board , they are very similar to each other, both have ic like your 1501-50, only these are 1506-50,
when you compare datasheets they are the same to me, my datasheet is
Same pinout + block diagram, the 2 ic of mine have continuity between 3 and 5, I have had no reason to suspect these 2 ICs , no discolouration on the boards,they both look in perfect condition,the 17'' I cannot see anything wrong with it, but the 15'' has burnt out current resistor on it, on the PSU side of it, between the mosfet source and the PWM controller so I believe this is the problem on this board, now to question,
Is it possible that your conclusion was wrong on your IC about it being bad ???
I read all your post and I know your capadility is very good, but I ask because the coincidence of them all being bad on diffrent boards is strange, and if you are right then I have a couple of hard tasks on my hands that I am not looking forward to, so I am hoping that is not so, I wait for your reply,