Hi,
it takes 5 tau to get it discharged....well, better use a resistor, here is a rule of thump:
R (Ohm) x C (Farad)= ½ dischagetime
A 10 or 20 Ohm resistor can do the job. Check the rest voltage!!! Have a look at wikipedia for the schematics aswell! Be shure that you disconnected the amp!
Please be very careful what you are doing! If I where you I would better visit a tech and watch what he is doing!
Greetings
Oli