De-energizer

[TIMBO]

Hi guys, What do you guys use to de-energize large filter caps. Thanks

[John]

A dead bunny.




Well, actually... a jumper wire with a 50k (or so) resistor in the middle, alligators on the end. Use a cheap resistor, because you'll forget and turn the amp back on with it still clipped in place. At least, I have . Several times. 

[DummyLoad]

47K 3W wirewound and a pair of clip leads.


--pete

[tonepumpamps]

A dead bunny.




Well, actually... a jumper wire with a 50k (or so) resistor in the middle, alligators on the end. Use a cheap resistor, because you'll forget and turn the amp back on with it still clipped in place. At least, I have . Several times. 

I thought I was the only one who's left that resistor hooked up 

[shooter]

Better than leavin the bunny hooked up, they only smell good 1st time around

[HotBluePlates]

Hi guys, What do you guys use to de-energize large filter caps. Thanks

A simple jumper cable with alligator clips on either end. After power is off, one end goes to ground, the other to the plate of V1. The series dropping resistors along the power supply rail limit discharge current enough to not risk arcing, and everything naturally gets discharged.

After a measured 0v at the main filter cap, you can move the jumper to that cap, just to make sure it doesn't "remember" a charge and build up voltage again.

Just remember to remove the jumper before applying power. Or don't; 1 or 2 blown fuses will teach you to check for it.

[ThomasE]

Hi guys, What do you guys use to de-energize large filter caps. Thanks

As you've read. There are many ways to accomplish this. In my opinion it's best to discharge caps "politely". I like using a "high" resistance although it takes longer to discharge your not dealing with arc discharge. (I'll also say that I've used just a jumper wire many times to accomplish this.) A while back I built a CDBB (cap discharge black box). It's 5 - 33K 2watt resistors wired in parallel. This results in around 7.5K of total resistance. For example if discharging a cap that might have 300VDC on it, you would have around .04 amps to deal with. However, take that resistance down to 10 ohms, now you're dealing with 30 amps. As you can see I have alligator clips and also a point of attachment for a vom to actually watch the voltage discharge. This topic is very debatable and there are a lot of guys out there that know more than I probably ever will about electrical theory but this is how I handle discharging caps. Good luck with whatever approach you go with. JUST BE CAREFUL!

[TIMBO]

That's COOL, Thanks

[HotBluePlates]

As you've read. There are many ways to accomplish this. In my opinion it's best to discharge caps "politely". I like using a "high" resistance although it takes longer to discharge your not dealing with arc discharge. (I'll also say that I've used just a jumper wire many times to accomplish this.)

Check out a Deluxe Reverb schematic (as a sample amp). Between the 1st filter cap and V1's plate, there are 2x 10kΩ resistors, a choke and V1's 100kΩ plate resistor. So you get 120kΩ plus the choke's surge-current-limiting to discharge the caps slowly.

No special tools needed!