dangerous voltages inside

Scott Stevens chenmel at earthlink.net
Sat Jan 14 00:58:11 CST 2006


On Sat, 14 Jan 2006 01:15:07 -0500
"Richard A. Cini" <rcini at optonline.net> wrote:

> Interestingly, there is no fuse holder at that location (bridged with a
> jumper). Instead, there is a standard 1-1/4" glass fuse holder in the back
> panel. Certain spots of the power supply board I've glued-over with
> insulating plastic (salvaged from the HV section of various power supplies
> over the years).
> 
> Very bad design indeed. The pads at the top are very close to the metal cage
> and the HV traces on the power supply board are uninsulated.
> 

The worst high voltage design I have ever seen was a Fluke
Digital Voltmeter that I used to have.  I think it was an 8300.
It used Nixie displays, and the high voltage for the Nixie tubes
ran on a trace that just weaved it's way across the circuit board
(with feedthroughs, etc,) without isolation or anything about it
to differentiate it from other traces.  The board was not
solder-masked, so the metal was bare and exposed.  Adjacent
tracks were low-level signal lines.

Granted, it was a high-end precision DMM so nobody was supposed
to go inside except the high-priest calibration dude, but
still....

Does anybody else here appreciate old Fluke gear?  My newest
piece is an 8060 DMM, which is late-70's 4-1/2 digit meter.  What
I really like are the Fluke Differential voltmeters.  I currently
have a nice 881AB.  The John Fluke Company made their name with
Differential Voltmeters and high-end lab-grade meters.  (I'm
biased against anything in a Fluke DMM without a 4-digit model
no., the 8060 is the best handheld they ever made, the newer
'autorange' lines have always been a disappointment to me.)



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