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Why solder to the back of a guitar's pot?
Old 7th June 2012
  #1
Lives for gear
 
🎧 10 years
Why solder to the back of a guitar's pot?

Hey all,

I'm finally getting around to replacing my strat's dead tone pots. All the diagrams I see have the ground being soldered to the back of the pot, along with a pile of upset guitarists grumbling about the difficulty of achieving such a task. The first thing that comes to mind for me is to put a ring terminal around the neck of the pot, attach to pickguard, and solder to the open end. Saves the back of the pot, stops me from worrying about burning a hole through the back of the pot, and achieves the same goal (yes?).

Am I missing something or are guitarists just too finicky about this issue to change?


Thanks!
Old 7th June 2012
  #2
Lives for gear
 
🎧 10 years
not enough metal contact imho. The larger the metal surface the better the ground thus the quieter your guitar will be. You can also line the inside of the cavity with metal flashing tape or aluminum foil to help cut down RF hum buzz etc as well.
Old 7th June 2012 | Show parent
  #3
Lives for gear
 
🎧 10 years
Quote:
Originally Posted by doulos30 ➑️
not enough metal contact imho. The larger the metal surface the better the ground thus the quieter your guitar will be. You can also line the inside of the cavity with metal flashing tape or aluminum foil to help cut down RF hum buzz etc as well.

Hmm (or is it 'hummmmmm'). Thanks for the heads up. What about bending the ring terminal and soldering that to the back of the pot? I'm not trying to reinvent the wheel, just trying to find a way that's easier for me.

As for the foil, do I just position it so the pots hold it inside? It won't rattle or make mechanical noise? If it's thicker, will it be more effective? I've got a roll of handyman's steel that works great for hole covers on amps and would be stiffer and thicker.


Thanks for the help!
Old 7th June 2012
  #4
Lives for gear
 
🎧 10 years
A lot of the back of the pot deal is just a matter of convenience. Lining the cavity with metal and then having the ring terminal be in contact with the metal will be a far better solution.
Old 7th June 2012 | Show parent
  #5
Lives for gear
 
🎧 10 years
Quote:
Originally Posted by johnnyc ➑️
A lot of the back of the pot deal is just a matter of convenience. Lining the cavity with metal and then having the ring terminal be in contact with the metal will be a far better solution.

Interesting. I feel like I said that but didn't realize it, yet you said it and it made complete sense haha. So use the handyman metal to connect the three pots behind the pickguard and connect a ground lug to one of em for the wires that need to get grounded?

Thanks! Sorry, it's been a long week, I hope I'm not being incredibly dumb here.
Old 7th June 2012 | Show parent
  #6
Lives for gear
 
🎧 10 years
Quote:
Originally Posted by Torea ➑️
Interesting. I feel like I said that but didn't realize it, yet you said it and it made complete sense haha. So use the handyman metal to connect the three pots behind the pickguard and connect a ground lug to one of em for the wires that need to get grounded?

Thanks! Sorry, it's been a long week, I hope I'm not being incredibly dumb here.
A lot of times the backs of pickguards will have already have the metal foil, but if not you can (should) add it. Would look like this: http://2.bp.blogspot.com/-e8LzgzqDDX...0/IMGP2651.JPG

Then yes after that stick a ground lug somewhere and send all the ground wires there.
Old 7th June 2012
  #7
Lives for gear
 
🎧 15 years
Hi
Soldering to the back of a pot is CHEAP. It is quicker and less expensive than fiddling with a 'solder tag' approach and it won't work loose and become intermittent over time.
There would be merit in a solder tag to ensure the shaft gets earthed, AND solder to the back too. Add metallic screening to the cavity as well.
Matt S
Old 7th June 2012
  #8
Gear Guru
That's usually the only place to solder a ground. Can't solder to aluminum. If it's difficult, it's either because you need to file away some plating, or the pot is a POS asian jobby made with a slag-olium metal that won't take to solder.

I use conductive plastic pots which are plastic constuction, nothing there to solder to so that lug is an option. Bourns supplies a solder lug with their "guitar pots".

I screen the entire innards with copper foil tape. That is my ground plane. If you do that on a Strat, be fast and light soldering to it or you may melt the pickguard.
Old 8th June 2012
  #9
Lives for gear
 
🎧 10 years
Thanks for the replies


Got my guitar opened up in what little free time I had today. Interestingly, it has the foil, but just under the pots/switch. Not around the pickups.

So what would be better as the cavity lining: Aluminum foil from my kitchen or 28ga sheet metal (~1/64" thick). I'm guessing copper foil tape would be better than both of those?

The sheet metal would be a bit of a pain to do, but I think it'd be possible. Probably can't solder to it but I've got tons of those ring terminals and several screws that I could stick one to.
I'm guessing the copper foil tape would be easiest, but I don't have that on hand.
Old 8th June 2012
  #10
Lives for gear
 
3 Reviews written
🎧 5 years
go with the copper foil tape. it is the best and easiest product to use. sometimes you can get it from a garden center, people use it to keep slugs off plants (apparently slugs dont like copper). otherwise ebay has a bunch of sellers that will sell you a foot or two for a couple of dollars... i think there is a lady in vancouver bc canada who sells this on ebay, she is very nice and ships VERY fast.

you want to make sure that the whole inner cavity is continuously covered, and that the copper makes connection somewhere to your ground. it can make great improvements!
Old 8th June 2012
  #11
Lives for gear
 
🎧 15 years
Hi Enginefire
Just read your post and somehow this bit caught my imagination:
[i think there is a lady in vancouver bc canada who sells this on ebay, she is very nice and ships VERY fast.]
It conjoured up an image of a little old 'granny' in a rocking chair in an 'out back' stereotypical 'Western movie' house saying, 'hello little boy, so you want to buy some copper foil?'
OK it's raining here, I'm bored and should be designing a PCB.
Watched 'Green fried tomatoes at the whistle stop cafe' the other night, perhaps that inspired the thought.
Matt S
Old 8th June 2012
  #12
Lives for gear
 
3 Reviews written
🎧 5 years
yeah Matt, shes at the old copper ranch on PCB way, a couple miles out of town!
Old 8th June 2012
  #13
Gear Guru
Around here, copper is a precious metal at $3.50 a pound. The locals have taken to removing it anywhere they can. Copper pennies are long out of circulation, those have already been melted down.

Street lights, traffic lights, any infrastructure with copper is targeted.

The "coppers" have been very busy lately trying to catch them.
Old 8th June 2012
  #14
Lives for gear
 
🎧 10 years
Alrighty, went to my local hardware store first thing today and got some Corry's Slug and Snail copper foil. 15ft roll, 1" thick for ten bucks.

Thanks for the help!
Old 8th June 2012 | Show parent
  #15
Lives for gear
 
Boschen's Avatar
 
🎧 10 years
Quote:
Originally Posted by Jim Williams ➑️
Around here, copper is a precious metal at $3.50 a pound. The locals have taken to removing it anywhere they can. Copper pennies are long out of circulation, those have already been melted down.

Street lights, traffic lights, any infrastructure with copper is targeted.

The "coppers" have been very busy lately trying to catch them.

Denver meth-heads have taken to stealing man hole covers, to the danger of the street-walking public.

This is no easy exercise; you need the right tool, and some muscle to move the covers... Christ, considering the effort involved, you'd imagine these folks could have started a business or some other legit enterprise...

Oddly enough, there's a segment of the meth community that also likes to scavenge for arrowheads in agro fields... something about being up at dawn, and eyes that never stop roving... go figure.


Lol at the 'Slug n' Snail'.... good name for an album... shades of 'Spartacus', or was that oysters and snails? Good ol Tony Curtis...
Old 9th June 2012
  #16
Lives for gear
 
analogtodd's Avatar
 
🎧 10 years
Bastards ripped a whole run of copper off the back of my building.... I good 150ft of runs.
They'd tried earlier in the year... (January) and the conduit was dead frozen and not going ANYWHERE. But they tried!!!!

Came back a few weeks later, when it was warmer and yanked it.
Old 9th June 2012
  #17
Gear Head
 
pzp9999's Avatar
 
🎧 10 years
Where im from the junkies steal hvac units. When they replace them theyve been mounting them on the walls of the building high off of the ground so as to make them harder to steal. Its easy money i guess considering the metal scrap place is a few blocks away. My roommate pulled a 12 gauge on one of them attempting to kick one off of its base in back of the tattoo shop i used to live beside. Pretty sure they got every business on the block eventually.

Sent from my DROIDX using Gearslutz App
Old 9th June 2012
  #18
Lives for gear
 
🎧 10 years
Got it all plated up, how's it look?

Took a few hours since I wanted to be extra careful with it (nobody's gonna see it but I'll know if it looks like crap). Tons of cuts on the tip of my finger, don't really know what part of the process was doing that though...


We've got a handful of somebodys out here stealing gas from the neighborhood cars. Was much worse when gas cost more, seemed to happen to at least one household a week among the 10 houses on this side of our hill. Locking gas cap seemed to stop that some.
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Old 9th June 2012
  #19
Lives for gear
 
3 Reviews written
🎧 5 years
man i must live in paradise, or some place that is pretty close... still lots of copper pennies, i get about 4 of them each morning when i buy my coffee. into the copper penny jar they go, the new ones get sent back into circulation. I went to an electrical supply store the other day to buy a couple bucks worth of solid copper wire to use as grounding bars, and the owner gave me 12 meters for free, like it wasnt really worth his time to write up an invoice. the week before he gave me a used copper buss bar, its like 4 feet by 2 inches by 1/4 inch thick. thanks for making me appreciate my surroundings and situation.

Torea, the pickguard looks good. dont forget to do the inside cavity of the guitar body as well, so that all the electronics are surrounded by a cocoon of sweet delicious copper!
Old 9th June 2012 | Show parent
  #20
Lives for gear
 
🎧 10 years
Quote:
Originally Posted by enginefire ➑️
man i must live in paradise, or some place that is pretty close... still lots of copper pennies, i get about 4 of them each morning when i buy my coffee. into the copper penny jar they go, the new ones get sent back into circulation. I went to an electrical supply store the other day to buy a couple bucks worth of solid copper wire to use as grounding bars, and the owner gave me 12 meters for free, like it wasnt really worth his time to write up an invoice. the week before he gave me a used copper buss bar, its like 4 feet by 2 inches by 1/4 inch thick. thanks for making me appreciate my surroundings and situation.

Torea, the pickguard looks good. dont forget to do the inside cavity of the guitar body as well, so that all the electronics are surrounded by a cocoon of sweet delicious copper!

Come to think of it, my parents have two 8 gallon water jugs filled with pennies. They've been ploppin em in there for something like 35 years. Wonder if they're worth more at the bank or the copper refinery...

I'll probably save the cavity lining until next time, since this time I was only originally planning on fixing my tone controls. I have a feeling I'm going to be popping the pickguard back off sometime soon to tinker with the controls and maybe add push/pull pots for the tone. I've been living with volume only for years, I have a feeling I might want to go back to that. Thanks though!

While looking for some examples of the cavity lining (I like examples), I found this site - GuitarNuts.com - Shielding a Strat(tm) - where it's recommended to add a .33uf/400V cap between the lug of one of the pots and a ring terminal with everything else attached, for protection in the event some amp dies and sends DC along the ground. I've never seen that recommendation before. Any thoughts?
Old 9th June 2012
  #21
Gear Guru
U.S. copper pennies have been made from zinc for decades now, just a copper plating. Problem now is the zinc in them is now worth 1.5 cents!

Time to melt those down.

Pickguard looks good. I solder all connections of the pieces together to retain electrical continuity. Oxidization will make those copper pieces not conduct after a few years. Now, continue with lining the wood body.

I also add the copper around the pickups or I line the plastic covers with it. Then there is no buzz.
Old 9th June 2012
  #22
Lives for gear
 
crosscutred's Avatar
 
🎧 10 years
Shielding is a good thing to do.

I wouldn't want to use that in place of a solder to make my earth connection.

I repair guitars for part of my income and I had a batch of budget guitars in recently from a school that relied on the screening for earthing and all 4 had earthing trouble that was repaired by soldering a wire across the back of the pots. That problem won't happen again on those guitars.

It isn't uncommon to encounter this and for the solution to involve adding a soldered wire on the pots.

Remember guitars take alot of stick sweat and beer spilt in them etc.
If it's not bullet proof it will fail on a working gigging guitar.

As for the cap to prevent electrocution.... if that was a real danger then why don't all the the guitar makers fit them?
Old 9th June 2012
  #23
Lives for gear
 
🎧 15 years
Hi
Some of the thought behind that cap 'mod' seems a little bizarre as the chances of getting high voltage DC out of a guitar amp are pretty remote as it would have to be referenced to something (ground) to have any great effect, by which time the whole amp chassis is 'live'.
This is on the basis that the amp has no ground conductor or has been 'tampered with', illegal in many countries.
Regarding to thefts of metals, it is not unusual for a half mile of underground telecomms multicore to 'disappear' overnight (dragged out of the ducting) and even great lengths of 11KV overhead power for the trains to vanish (presumably live at the start of the theft!).
Matt S
Old 9th June 2012 | Show parent
  #24
Lives for gear
 
🎧 10 years
Quote:
Originally Posted by Jim Williams ➑️
...

Pickguard looks good. I solder all connections of the pieces together to retain electrical continuity. Oxidization will make those copper pieces not conduct after a few years. Now, continue with lining the wood body.

I also add the copper around the pickups or I line the plastic covers with it. Then there is no buzz.

I added some solder between the pieces. The top 3 pieces weren't conducting with the rest of the pieces so I soldered in two places on each seam. Do you mean you go all the way across the seam with solder?
I'll probably add some around the pickup covers, since that's very easy to do.




As for the cap: Yeah, I figured it was kind of out there, but as I use Leslie connectors that send B+ to the Leslie amp using the ground line I wasn't sure. Made me curious
Old 10th June 2012
  #25
Lives for gear
 
🎧 10 years
To ground the copper in the pickup covers, do you just wrap it out and let it contact that suspension spring?

Doing the guitar cavity today. Hoping to get it done by tonight
Old 10th June 2012
  #26
Gear Guru
Use a DVM to check continuity. One piece of solder is enough. I hang a small piece of foil off the side of the plastic pickup cover after it's wrapped insides and ground that. Check with the meter to avoid any shorts. I usually wrap the coils in electrical tape first to insulate the coils. It can be tricky to do this successfully, but the results are zero buzz.

Which way the coils are run can also affect noise pickup. If the inside turns are hot, then the magnets become noise sensitive, check that by touching the magnets with your fingers. If run outside coils as hot, then the magnets are closer to ground potential and are less likely to pick that noise up.

In stuff like a p-bass, one coil will always be inside turns hot so I place a piece of electrical tape across the pickup pole pieces to avoid touching them.
Old 10th June 2012
  #27
Lives for gear
 
🎧 10 years
Alrighty, got them grounded to the spring by leaving a little bit of copper out. Everythings continuous.

The pickups are covered with something thin, couple of winds with tape still fits under the cover. Bit tight.


Doin the cavity after lunch. Thanks for the help!
Old 11th June 2012
  #28
Lives for gear
 
🎧 10 years
So I just finished doing my tests. Decided to skip the cavity lining for now, my fingers are too beat up and I have a feeling I'd mess it up somehow. Anywhos, the copper lining worked out quite well, very little buzzing, though there is some hum above 7 on the volume knob. Seems as long as I keep it at 7 or below it's pretty quiet (even if I turn up the amp).

One issue: The bridge pickup doesn't work. Don't know what happened, I checked everything for good solder joints and continuity before putting it all back together. I think I'll wait until I restring it or it starts bothering me to fix it, since I'm poor and don't want to buy new strings after 15 minutes of playing. Luckily I usually use the middle pickup for lead and the neck/middle combo for rhythm so I think I'll be OK. Oddly enough, there is less hum at the bridge/middle setting of the 5-way switch then there is at the neck setting even though the tone doesn't change at all. Any ideas as to what happened?


Thanks again for the help! Eventually the cavity will get lined and that will hopefully remove the remaining hum, but seriously, my right hand fingers are all cut up!
Old 24th June 2012
  #29
Lives for gear
 
lame pseudonym's Avatar
 
🎧 15 years
Interestingly, the pots that Mouser sells as "Guitar Pots" solder (on the back) very readily. Which was not the case with the previous generic pots that they sold.

If you don't ground the pot, there'll be a little antenna (the shaft) coming out the front of the pickguard, which will hum a bit when you put your hand on the knob. You can't really trust a foil contact to keep this secure.

LP
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