No hum when touching either cable jack

Started by gutsofgold, March 10, 2008, 12:35:35 AM

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gutsofgold

I'm getting some serious humming from a recent build. When I touch one of the cable jacks (either in or out) half the hum goes away. Then I touch the other and there is no hum at all. I've been through my wiring a hundred times and the grounding is fine. Its running from the battery ground to the input ring, input sleeve runs to output sleeve and to the board ground. The board also runs ground to appropriate pots and to the center post on the 3DPT switch.

I should also note that I am using the cliff style jacks this time. Do I have to connect anything to the three lugs on the stereo jack that my cable jack does not touch?

gutsofgold

These are isolated jacks!  ;D Can you tell I am still new to this?

Would it be reasonable to run a cable from any of the grounds and solder it to the enclosure?

gez

#2
Quote from: gutsofgold on March 10, 2008, 12:43:05 AM
These are isolated jacks!  ;D Can you tell I am still new to this?

Would it be reasonable to run a cable from any of the grounds and solder it to the enclosure?

Assuming the enclosure is metal, then yes.  A wire directly from the negative of the power would be best, but anything is better than nothing. 

PS  It's almost impossible to solder to aluminium (although someone once posted a method on how to do it), so you'll probably have to use a 'solder tag' (metal ring with a tab for wire to solder to), attached via a small bolt or an existing feature (your jack sockets, for example).

[Edit] these things:

http://www.maplin.co.uk/Module.aspx?ModuleNo=29815&C=Froogle&U=29815&T=Alias&MA=tin%20solder%20tag
"They always say there's nothing new under the sun.  I think that that's a big copout..."  Wayne Shorter

gutsofgold

Thanks.

Could I connect ground to the nut or washer on the 3DPT switch?

gez

Quote from: gutsofgold on March 10, 2008, 11:26:08 AM
Could I connect ground to the nut or washer on the 3DPT switch?

So long as there is connectivity between the box and what you attach the wire to, then sure.
"They always say there's nothing new under the sun.  I think that that's a big copout..."  Wayne Shorter

gutsofgold

Hmm grounding to there isn't going to happen anytime soon. I also tried soldering the ground lug of one of the pots to the pot body but the solder simply would not stick.

I guess I will try those solder tags...how do they attach to the case though?

I've seen these jacks used on many pedals posted on here, could someone offer some advice?

Chawk

One way would be to drill a hole in the box and attach the tag with a small nut and bolt.
"Why don't those stupid idiots let me in their crappy club for jerks!"--Homer Simpson

gez

Quote from: gutsofgold on March 10, 2008, 02:14:18 PM
I also tried soldering the ground lug of one of the pots to the pot body but the solder simply would not stick.

A wire to your pot's casing would be a good way to do it.  Use flux and a nice hot fat tip (stop snickering at the back!)  Alternatively, sand the area before soldering.

QuoteI guess I will try those solder tags...how do they attach to the case though?

As mentioned, drill a hole and bolt the tag to the box.  What I would do is drill a hole in each corner of the base and attach bolt on feet.  Use one of the bolts to kill two birds with one stone.  A wire to the pot casing is going to be easiest, though.
"They always say there's nothing new under the sun.  I think that that's a big copout..."  Wayne Shorter

gutsofgold

Ahh so I grounded to the pot. Used lots of flux and lots of heat and that glob of solder stuck!
This however brought about problem number two. Whenever I touch any metal part of the enclosure, the pots, the switch, either cable jack, etc... The sound phases in and out. I can touch even any part of the enclosure itself and the signal sort of waves in and out.

gez

#9
You must have miswired something.  Are you sure it was ground that you soldered to the pot?
"They always say there's nothing new under the sun.  I think that that's a big copout..."  Wayne Shorter

petemoore

  Check that all the ground connectionss are common.
Convention creates following, following creates convention.

gutsofgold

Quote from: petemoore on March 12, 2008, 06:47:45 AM
  Check that all the ground connectionss are common.

Does mean that all ground connections EVENTUALLY make their way to the top of the potentiometer? For example, just bridge the ground lug of the pot to the top of that pot. Thats essentially a ground connection and that is connected to all other grounds. That is exactly what I did before and it lead me to the problem I explained in my previous post.

Or would it be correct to take the - connection of the battery, run that sleeve of the input which then gets run to the sleeve of the output and run those to the pot for ground. And also run the board ground to the pot as well???