I'm copying this from my own instructable about tube amp rebuilding
DISCHARGE THOSE POWER FILTER CAPACITORS!!!!!
Seriously. Do this EVERY TIME you work on the amp.
If you don't, DO NOT complain if you loose the use of your hand. DO NOT come back
and haunt me
if you die....
The power 'filter' caps can store fatal amounts of electrical current, and are sometimes termed "reservoir" caps. The caps are connected near the rectifier and are part of the power supply, and aid in converting AC to DC. In fact, they are a standard component in any power supply.
If you're completely lost, and don't understand this
, DON'T MODIFY YOUR AMP
. You haven't enough knowledge to work on high voltage/current circuits safely...
There are several ways to discharge caps, but here's the easiest:
FIRST, UNPLUG THE AMP!
(But that doesn't make it safe....)
-- Jumper the positive (+) lead of each large cap to GND for several seconds. A jumper with a built-in resistor (10K or so) will help prevent sparks here... If your jumper has a resistor, leave it connected for at least 30 seconds
before you touch anything.
-- OR short the caps with a screwdriver. Lay the shaft on the chassis, then bridge to the positive (+) lead of the cap. Be sure the screwdriver handle is insulated (if it's painted, it might not be.)
This may result in a spark... Obviously, your flesh can act as a jumper also (that is NOT a challenge.)