[This followup was posted to sci.electronics.repair and a copy was sent
to the cited author.]

In article ,
says...


If available, I would strongly recommend the use of a proper bench isolating
transformer when working on this. I'm sure that it is probably a case of
grandmothers and egg-sucking as you seem to be saying the right things, but
just in case ...

Switchers are of course extremely dangerous on a 'raw' line supply. I
usually have a variac connected as well. This can be either a help or a
hindrance depending on design, but I always initially make the assumption
that it is going to be a help, when I don't have a schematic. Although some
supplies have UVLO on the control IC, so won't start with a reduced input
voltage, it does at least allow you to carry out checks on - for instance -
the startup supply, in a safe manner, and without the risk of a Disney-esque
fireworks display, when your meter or 'scope probe slips, which it always
will sooner or later, depending on how urgent the job is, and how rare the
supply is to obtain a replacement for ... :-)

Good luck with it, and do let us know how you get on !

Arfa

I will post back here when more work on this power supply has happened.
Normal workweek obligations force one to set aside tasks like repairing
monitors.

--

Michael Karas
Carousel Design Solutions
http://www.carousel-design.com