discharging a G07 B+ cap

Zork2

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Can someone explain to me the "proper" way to discharge a B+ cap on a G07? I hear they can give you a hell of a shock!
 
It would actually be great to see a quick video of it. I don't know what the hell I did wrong, after I touched the leads to the cap and got the pop I thought I was ok to go. I still got a little bight from it. I have not touched it since, in fact I got so ticked off I almost threw it in the dumpster.
 
lol... I had a bunch of G07 chassis sitting on a metal shelf. Had my friend move / sort them and "POP" ;-)

Sounded like a gun shot... He wasnt pleased
 
Discharge it just like you discharge the tube. Attach a jumper wire between the frame and a screwdriver (with insulated handle) and touch both sides of the small fuse. Get ready for a big POP that will scare the crap out of you even if you expect it.

Usually you get this if the fuse is blown, but not always...
 
yeah it's an impressive sound. gets me every time and like mod said, I am expecting it.

It can be a little awkward getting your screwdriver to touch both posts on the filter cap, but it should just take a few seconds.

If a guy got zapped after discharging it, treat it like a monitor from now on and discharge it 2 or 3 times before messing with it.


every time I do this I say to myself, "damn I am glad I didn't get bit by that" :)
 
Use a 60 to 100 watt common household light bulb (120 volt) to discharge the cap. Much safer that way and it won't hurt the bulb.
 
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you need to get loose socket to use with it. Then put Aligator clips or something on the end of the wires then just touch both sides of the fuse. That's how I understand to do it. I never done it before where I seen the bulb lit. Is a 12v car bulb alright to use? That what I got with my make shift tool for this.
 
How exactly would you do this, Ken?

I use my work light.....alligator clip the metal part of the chassis (or any ground point) to one prong of my work light's plug.......alligator clip the other prong to the positive side of the cap. Flip my work light's on/off switch to the on position........light will illuminate for a second or so......cap is now discharged.

Edward
 
No.. theres 100+ volts on the cap. it will smoke a 12v bulb.

Caps don't have volts, only stored charge. The voltage seen at the bulb will be a function of the resistance presented and the charge stored. A much more important metric is the wattage of the bulb.
 
use a 10k resistor, maybe a larger valued one across both cap leads.. experiment..
put your millimeter across the cap leads to watch the dc voltage drain.
a direct short will cause a vicious pop.
 
Very true..Sorry for the confusion. My intent was that it was part of the 100v B+ circuit.

However a 12v bulb will have a much lower resistance then a 120v bulb with the same wattage.
 
You can discharge any cap very easily with a pair of needle nose pliers. Open the pliers to match the lead spacing of the cap, and short it out.

-Ian
 
Can anyone explain why my HV probe wont discharge the filter cap? In cases where the fuse is blown I have tried to discharge the filter cap with the HV probe and it does not work. I usually use an alligator lead and a screwdriver but I think I will start using the light bulb method. Even when you know the pop is coming it still scares you.
 
I have discharged the filter cap, waited a minute and discharged it a second time and gotten a smaller spark out of it. Be careful if you only discharge it once.
 
Thanks guys, great thread.
I hope this clarifies things for more people than just me.....
Think I'll use the light bulb method, that POP just scares the H3LL OUT OF ME every single time! :)
 
If you have a small table lamp that uses a normal light bulb, use that (make sure the lamp is on and the bulb works). Unplug the lamp, get a couple alligator clips, attach one between one prong on the lamp plug and the other to the monitor frame, attach the othe to the other prong on the lamp plug and then touch the far side of the blown fuse. If there is a charge, the bulb will light up, then dim as the charge bleeds off. Once the bulb is dark, it's safe to mess with...
 
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