* On Fri, Apr 08, 2016 at 02:33:25PM -0400, Mouse <mo...@rodents-montreal.org> wrote: > > Today, for whatever reason, my Variac was turned down to 110V, and I > > didn't notice. I turned on the ADM 3a, and... it's fine. [...] > > Fascinating! > > I have trouble imagining what sort of fault could cause those symptoms. > I would have agreed with whoever (tony, I think) said that if you have > HV then the horizontal scan is almost certainly operating in some > sense, but this makes me doubt that. I have trouble coming up with a > failure mode in that design that could kill the horizontal scan but not > the HV based on the power supply input voltage, so there is probably > something very unusual in there.
It IS odd. One more observation: Two of the three +5V regulators cut out when their input voltage exceeds about 11.5V. The input voltage comes from a 9.4VAC winding on the primary transformer. Input ripple is VERY low, maybe 200mV. So, I suspect those regulators need to be replaced. I'm sure it needs to be recapped, too, so I'll do that before I investigate too much furtther. -Seth -- Seth Morabito s...@loomcom.com
