Power Supply

I have no output on the secondary. Thus not having any voltage at the Opto coupler and that in turn should make the IC try to compensate for the loss. But it doesn't. Now I checked all the voltages and the 168 V was fine. Looking up the IC infor I found out that its only supposed to have 10-16v in, but instead it has 68v. Why, I don't know. I checked the resistor and it is fine. And it drops voltage. At one point I remember checking the in voltage to the IC and it was varying 11-15v. Good, but where did it go? Now the output of the IC is supposed to be a square wave into the gate of the MOSFET. Pulsing it. Thus making this power supply and switching power supply. I really don't know how to explain my problem, except that I know it is in the primary and I have 0v out of the transformer. What I need help from you all who enjoy power supplys, is what, where, how, and why. What is causing this and why, where could the problem lie, and how should I go about checking it.

I know it is kind of hard without a schematic to look at, but if you know anything about switching power supplys, you should know the schematic. Or maybe you could find one.

Now I replaced the IC with a new one and it still didn't work. But I was hoping that that would fix the problem in the first place. Now I am stuck.

Also, the reason why this is all happening is because in the product it is in was struck by lightning.

I would appreciate any advice anyone of you can give me. Or maybe some insites.

When this IC is UC3842 check the 50...100uF on supply pin.

Everything checks okay. But I still don't get an output. Why.

Send me a circuit diagram for study,please.

can't do. Sorry. I'm going at this blind. But if you can find a schematic of a switching power supply, it should be around the same.