Re: 475 questions


Hi Ernesto!

Thanks for the excellent advice! I have been looking at new and used variacs with that in mind. However, after I built the incandescent bulb current limiter this morning, I felt that I could probably get away with turning on the scope, which I did without any (to me) known negative consequences. I let it run for several minutes. The bulb just glowed faintly. I would have preferred that it glow even more faintly or not at all, but I did not have a larger wattage bulb than a 150. My guess is that for this scope, 200W would be the ideal bulb. After seeing no ill effects, but all voltage readings low, I shut it off and replugged it into the wall receptacle. It ran fine (no trace, but nothing seemed to pop, get hot, or release smoke) for the half hour or so that I ran it. The voltage readings I took when it was plugged into the wall rose with the bulb removed, but did not reach spec. The measurements I got are recorded in my post #167295 below. My 50V didn't get above 40, so only 80% of what it should have been.
Yes, I wish I knew how to isolate the problem(s) better. At this point, I think I'm just going to start changing out old capacitors and rectifiers.

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