Grounding to back of pot

[davent]

That's how i would do it and i would use a star washer on the bushing between the jack and the inside of the enclosure, helps keep things tight and you've better connectivity between the two surfaces. Any metals in contact with the metal box will be connected to that jacks tab.

This style of star washer, i think 3/8"/10mm is the size for a 1/4" metal jack bushing.


dave

[skern]

That's how i would do it and i would use a star washer on the bushing between the jack and the inside of the enclosure, helps keep things tight and you've better connectivity between the two surfaces. Any metals in contact with the metal box will be connected to that jacks tab.

This style of star washer, i think 3/8"/10mm is the size for a 1/4" metal jack bushing.


dave

Nice! And if I understand correctly, that means I can get 2 of those washers and do the same thing on BOTH 1/4" jacks so that I don't have to solder either of their sleeve contacts. So now I'm down to just 2 ground connections, i.e. wiring the 9v DC ground and the pot ground to either one of the 1/4" sleeve contacts. Does it really matter if I connect one wire to one of the jacks and the other wire to the other jack, to avoid having to solder two wires to one lug? That's not really a big deal, but I remember reading that it's advisable to have a "common" ground point, but I don't really understand why, since everything is connected electrically anyway.

EDIT: Uh oh, I think I got ahead of myself. I realized on one of the jacks I am NOT connecting the sleeve contact to ground. So if it can't be grounded, that means I can't have the box grounded, unless I replace the jack with one of those completely isolated 1/4" jacks.

EDIT 2: Ok so, if I want to rig this up in some way that doesn't ground the enclosure, is it possible? Do I just connect all ground connections to the ground lug on the 9v DC jack?

[bluebunny]

Don't rely on the jack's bush (or washer) to make your ground connection to the enclosure.  If the jack becomes loose, then so does your ground connection.  Make the solder connection properly.  This isn't a competition: there are no prizes for fewest ground connections. 

[skern]

Don't rely on the jack's bush (or washer) to make your ground connection to the enclosure.  If the jack becomes loose, then so does your ground connection.  Make the solder connection properly.  This isn't a competition: there are no prizes for fewest ground connections. 

Yeah that's true, I'm just trying to minimize wires cause I'm using one of those tiny square enclosures.

So I can just solder everything to the ground lug on the DC jack?

[bluebunny]

Just pick somewhere you can actually put all your ground wires (the lug on a DC jack is unlikely to be big enough).  BTW, it's not strictly necessary to put them all in the same place.  (Someone will doubtless shout "ground loops!" at this point...)  I often split duties between the input and output jacks, joining them together with (ideally) a fat piece of wire if I'm feeling virtuous, or just the same stuff as all the other connections.

[skern]

Just pick somewhere you can actually put all your ground wires (the lug on a DC jack is unlikely to be big enough).  BTW, it's not strictly necessary to put them all in the same place.  (Someone will doubtless shout "ground loops!" at this point...)  I often split duties between the input and output jacks, joining them together with (ideally) a fat piece of wire if I'm feeling virtuous, or just the same stuff as all the other connections.

Nah, I just realized I'm screwed. One of the jacks must be grounded, and the jacks I'm using have the bushing connected to the sleeve, which means the box will be grounded, which means my other jack will be grounded, which ruins the circuit.

EDIT: I don't suppose there's a way to somehow isolate the bushing from the box...

[GibsonGM]

If you CANNOT have the other jack grounded, you can use an isolated jack (they use them in amps all the time, but it means you have to wait to get it); it doesn't make chassis contact.  Or just use a screw thru the enclosure w/the star washer if that's not totally out of the question...

[antonis]

You can use ANY ground point as common ground, as long as it's somehow connected to power supply ground.. 

edit: Wrong page answer.. 

[davent]

Don't rely on the jack's bush (or washer) to make your ground connection to the enclosure.  If the jack becomes loose, then so does your ground connection.  Make the solder connection properly.  This isn't a competition: there are no prizes for fewest ground connections. 

Marc you've lost me here, i read it as you are soldering a wire to the enclosure to connect it to circuit ground?

I wire power ground directly from the power jack to the pcb. Signal ground i've always run a wire from the ground tab of 'one' of the open frame jacks to the pcb and i'm done.

Nice! And if I understand correctly, that means I can get 2 of those washers and do the same thing on BOTH 1/4" jacks so that I don't have to solder either of their sleeve contacts. So now I'm down to just 2 ground connections, i.e. wiring the 9v DC ground and the pot ground to either one of the 1/4" sleeve contacts. Does it really matter if I connect one wire to one of the jacks and the other wire to the other jack, to avoid having to solder two wires to one lug? That's not really a big deal, but I remember reading that it's advisable to have a "common" ground point, but I don't really understand why, since everything is connected electrically anyway.

EDIT: Uh oh, I think I got ahead of myself. I realized on one of the jacks I am NOT connecting the sleeve contact to ground. So if it can't be grounded, that means I can't have the box grounded, unless I replace the jack with one of those completely isolated 1/4" jacks.

EDIT 2: Ok so, if I want to rig this up in some way that doesn't ground the enclosure, is it possible? Do I just connect all ground connections to the ground lug on the 9v DC jack?

I'll use the star washers for all 1/4" jacks & pots (take a smaller size).
dave

[skern]

If you CANNOT have the other jack grounded, you can use an isolated jack (they use them in amps all the time, but it means you have to wait to get it); it doesn't make chassis contact.  Or just use a screw thru the enclosure w/the star washer if that's not totally out of the question...

Think I'm gonna go with a couple of these fiber shoulder washers. I'd get a fully insulated jack but it's a tiny bit larger than my current jack, and I've got things right up against the walls as it is, so I'd rather not risk it.

[bluebunny]

Marc you've lost me here, i read it as you are soldering a wire to the enclosure to connect it to circuit ground?

I think I said it back to front.      Don't rely on the enclosure conferring a ground connection on the jack.

[amptramp]

Just don't do what they did in my Cort guitar.  They soldered the ground connection of the three pots (neck volume, bridge volume, tone) to their respective pot backs then relied on a piece of foil for the connection between the three pot backs.  So you had an interface that consisted of the pot backs mechanically folded over the pot fronts then the pot fronts going to the foil.  Any corrosion changes the connection and resulted in a lot of noise and day-to-day variations in performance.  Then I soldered the three grounded tabs of the pots together and to the jack and on the other side, the pickups.  Now the guitar is quiet and a professional guitarist who works part-time at a musical instrument shop has decreed it to be a great blues guitar.

It is shown on page 16 of the "show us your guitars" picture thread in an image damaged by photobucket.  The added ground wire is yellow: