Friday, January 23, 2009

Discharging Filter Caps - The Basics Pt 2



Here's hows how a discharge probe is used to bleed voltage off of a capacitor. This cap is completely removed from the circuit for illustrational purposes, but the procedure is the same when a cap is installed in an amplifier. The meter is tough to read here but I hope it's good enough to get the general idea.



The resistor at the clip end of the probe is a 56K 3 Watt one covered in two layers of shrink tubing for safety. The resistor will limit the current from a 450 Volt supply to under 10 ma but it is still a very good idea not touch the alligator clip end of the probe while connecting the other end to the B+. I'll cover the probe construction in a later post.

THE UBIQUITOUS DISCLAIMER: AKAVALVE ASSUMES NO RESPONSIBILITY FOR THE SAFETY OF ANYONE IMPLEMENTING THESE INSTRUCTIONS. IF YOU ARE NOT FAMILIAR WITH SAFE PRACTICE IN HIGH VOLTAGE CIRCUITS, DO NOT ATTEMPT THIS YOURSELF.




2 comments:

Fernando fdi@ran.es said...

I'm enjoying, learning... thank you so much!
Won't you add the "one hand in your pocket" traditional golden rule here?

Rich Parker said...

Excellent, thanks - looking everywhere for a clear explanation of how to discharge caps safely, using correct tools, methods and common sense.

I'm going to build a small tube amp (Champ/Princeton or Deluxe) so reading lots first - will look around your blog for more good info!

Cheers!
Rich