PCB milling machines and shorts...

[Hallgeir Helland]

Harry Bissell wrote:
> 
> Yeah: I like a BIG capacitor charged up to 50 volts or so (more if you have
> "big brass ones")... Tie them to the board... Its like the Trauma Center....
> Nurse, we're losing him... Paddles... Clear... BLAM !!!!   :^)  Harry (semi OT)
> Bissell

Sorry, I feel I have to share something I did a few years ago..... I'll be
brief.

Had made a tube preamp. And a high tension (420 V approx) PSU with two 200 V, 
1200 uF caps (= 600 uF @ 400 V). Had tested the circuit, it worked. Pulled the
plug, decided to wait for the high tension to "go away", as I thought. It
didn't. (I had no bleeder.) So I put on a 10 kohm resistor, waited 10 minutes.
Still 420 V. Got fed up. Poked it with a screwdriver. Bang. Smoke and sparks.
Veroboard tracks GONE. Still 350 V across the caps and 200 BPM heart rate.

We live and we learn.   :-)

Hallgeir
-- 
.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.,.
 Hallgeir Helland   hhelland at mailandnews.com     
    Evlogia           http://fly.to/evlogia
'¨'¨'¨'¨'¨'¨'¨'¨'¨'¨'¨'¨'¨'¨'¨'¨'¨'¨'¨'¨'¨'¨'