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Vintage threads from the first ten years
discharging caps....
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 9/9/2004 2:39 PM |
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nathan hiltz |
discharging caps.... is turning up your guitar, strumming the strings repeatedly, and then turning the power off on the amp an effective way to dishcarge the caps on my 5e3? THanks alot! |
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| 9/9/2004 2:45 PM |
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| Chris @ CMW amps |
Hi Nathan It should but most of the time caps do "recharge" themselves. Sometime ago there was a thread about putting a 220k resistor on the 1st e-cap ( to centre tap OT ) for discharging duties but even in that case there will be some voltage again.... I do the following when working on an amp; - put the amp off while playing - then put a 470/5W resistor between B+ and ground - then check for voltage ( usually below 20 Volts ) - again the resistor between B+ and ground Altough this should be a bench-rule for me I do forget it about a couple of times a year..... 
Chris |
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| 9/9/2004 2:48 PM |
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| nathan hiltz |
i got my first zap the other day - i was trying to track down some cabinet rattle so i had the amp open, power on, guitar strapped to make the rattle happen, and chopstick in hand. I then proceeded to accidently touch the fuse post with my thumb while poking tube sockets. Ouch! |
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| 9/9/2004 8:50 PM |
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| TJ | Here is what I am going to use...What do you think? http://bwilliamson.home.mchsi.com/discharg.htm |
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| 9/10/2004 7:28 AM |
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| Newt |
I use a rig like that. I have a 1k cement block resistor and insulated alligator clips. Just remember to take it off before you power up! |
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| 9/10/2004 1:34 PM |
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| Carl Gigun |
On my amp with a 220k bleeder resistor the voltage goes down from 400 to zero within 15 seconds after turning off the amp. The voltage does begin to grow again, but it only gets to 4 volts then goes back to zero. The clip leaded resistor is definitely the way to go for amps that don't have a bleeder. You're not supposed to discharge the caps by shorting them with an insulated screwdriver or whatever, it's bad for the caps. -Carl |
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| 9/10/2004 1:47 PM |
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| bnwitt | 1. Take an insulated alligator clip jumper wire. Ground one end to the chassis at the green wire from the power cord ground point. 2.Connect the other end to pin 1 of the first preamp tube (V1). Leave that jumper in place for about 20 seconds. This will discharge the amp slowly and safely through the tubes internal resistance. Courtesy of Geral Weber |
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