Well, we've all heard the term "magic smoke". While tinkering in a 2500Vdc supply, I did just that to my Fluke 8050A bench top multi-meter. It let out that sorta of hollow sound of air blowing. Its not rated for that kind of voltage. I usually use an old HP VTVM & high voltage probe, but totally spaced out and crammed the + probe of the Fluke in there.
Oh well, I downloaded the schematics, cracked it open, and found that the Fluke has 3ea 430v MOVs in series across the input for protection. Yay! I clipped them open, and all was well, so it was an easy repair.
While I was at it, I made a couple of "down and dirty" HV probes to allow me to poke around in maybe up to 3kv. The DVM has an input impedance of 10megohms. A couple of junker probes served for this quickie mod. To the tip of one, I soldered a 10 meg 5w resistor to the end, using the resistor as the probe tip. To the other, I soldered 2ea. 10 meg resistors in series. The probe with one is /2, 900 v measured is actually 1800 v. The probe with two is /3, so 900v measured is actually 2700 v. This is DANGEROUS, be careful if you try my foolish trick, but it works for me.
Dave WB4IUY
