Getting erratic voltage reading near and around IC901 (over voltage detection IC). Voltage goes from 0v - 4v back and forth at the base of Q902 and generally around that area. On the schematic the voltage at that point should be 0.4v. I have checked all capacitors and can't seem to find any bad ones, infact I've checked for bad caps or transistors on most parts of the set but can't seem to find what is causing the problem. I thoght that I should mention the erratic voltage though as that is about the most promising thing that I have found. At first I though it may be an over voltage problem on the horizontal output circuit which was tripping out the over voltage protection cicuit but now I'm beggining to wonder if the problem may actually be the over voltage cicuit or the chopper circuit which are both connected and the same cicuit really.
I was also wondering if it may be something breaking down under load due to the fact that the set will not trip out when the HOT is removed. So it seems that the problem only happens when the set is under load.
Would really appriciate some help with this as I've been trying to get this set working for a long time now and it's starting to do my head in.