Knob control issue

[Jazz Rock]

Oh yeh ! Oh yeh Brave gens !

I wrote a thread last month in which I was having doubt about the good functionning of the knobs on my Studio, after hearing the difference I can make by playing with the new knobs of Epi.

So this week I decided to open the knob cavity to see what it looks like. My knowledge wiringwise being close to zero with a negative value, is there anything I can do to improve the functionning of these knobs by tweaking the wiring (see picture)? Or is it only an issue of pots quality?

 

[Amateur]

Re: Knob control issue

I think you can switch to single point grounding and that's about it, unless you want to fool around with the value of the capacitor. Definitely not in side the pots.

 

[amputee]

Re: Knob control issue

Jazz,
I agree with the above..except I hate shared caps I tend to have one per tone pot.. Is there any problem with the pots themselves eg notchy in operation or noisey.If you want to switch to single point grounding .. get a hot iron 50 watt plus about it good luck its not as hard as it looks ( honest)

 

[Jazz Rock]

Re: Knob control issue

Thank for the input Amateur and Amputee.

I am totally new to this and am actually in the process of finding a soldering iron. In another thread I was told you should be able to do all soldering works on a guitar with a 25w iron. Do I really need a 50w for the single point grounding?

Now, if you got more spare time for a little explaination...
I think I understand the concept of single point grounding but which wires would it involve? What is the benefit of this?

On my other LP, I have seen the capacitors are plugged only to the tone pots. What difference does it make?

The handling of the pots has no problem, it's just the effect they got on the sound I'm not happy with:
+ With the volume pots, I am exagerating a wee bit but they pretty much work as a switch on/off.
+ The tone pots just cut the trebble and make each pickup sound dull.

Finally, could it be the pots themselves that are faulty?

 

[Amateur]

Re: Knob control issue

If you do single point ground, you should take all the ground wires and the shieldings and solder them to ground at one location. I did mine at the back of one of the tone pots.

The capacitor and the tone pot combined to form what we usually called an RC (resistor and capacitor) circuit, which breeds the high frequencies to ground. It does not matter if the capacitor or the pot (which is an adjustable resistor) is connected to the sound source first before the circuit is grounded. You have two tone pots in your LP and that is why you have two capacitors.

I don't know exactly what kind of problem you are having so I can't tell you exactly what to do; but to find out whether a pot is defective, you can hook up the positive wire of an ohm meter to the center tab of the pot and the other wire to either tab on the side and then turn the knob, you should see the resistance change when the knob is being turn. Hunbuckers usually have 500K pots and 0.047 uf capacitors. The resistance change should be somewhere from 0 to 500K +/- 10%.

The volume pots control the voltage that comes from the pickups. The higher the resistance, the lower the voltage you will get and that means lower volume.

From the look of the pic, you have changed your pickups and something looks suspicious at the middle tab of the pot located at the lower left coner. I don't know what that is. It may be just the angle that makes it look that way. It should be nothing there except a wire soldered to the tab.

 

[amputee]

Re: Knob control issue

Jazz. again I agree with amateur.Re looking at the pic it does seem slightly non standard . The reason I suggest a hot iron for the earthing is the time takem to heat the body of the pot can take ages with a 25 watt as the body acts like a heat sink . If your realy are worried pop it to your local store and see a guitar tech most are great people (plug) . The trouble is we all have different ways of doing the same thing and they are normally all right ... confusing isnt it .. if you want any help e-mail me will be happy to advise.

 

[ErikH]

Re: Knob control issue

A good variable temp iron from 5-40 watts will do, and is nice to have around because you don't need the full 40 watts to solder the tone caps and wires to the lugs but you do for the back of the pots. However, rather than grounding everything to the back of one of the pots, a better way is to star ground.

http://www.guitarnuts.com/

See the Quieting the Beast mod. The instructions are for a Strat but can easily be done to any guitar. Ignore the big 400v cap in the instructions and just put a wire in its place.

 

[amputee]

Re: Knob control issue

Had a re re look .. the wiring seems to make no sense would you like a wiring schematic jazz.. The tone caps seem to be connected to earth on both points or is it just my eyes... I can do a schematic and and realistic layout if you would like...

 

[ErikH]

Re: Knob control issue

Had a re re look .. the wiring seems to make no sense would you like a wiring schematic jazz.. The tone caps seem to be connected to earth on both points or is it just my eyes... I can do a schematic and and realistic layout if you would like...

Lug 1 of each tone pot is bent and soldered to the shell. This looks weird because all the controls are mounted to a metal plate. That plate is the common ground point. Hence why it appears to have missing ground wires. that's actually a cool way to eliminate ground loops.

 

[Jazz Rock]

Re: Knob control issue

Had a re re look .. the wiring seems to make no sense would you like a wiring schematic jazz.. The tone caps seem to be connected to earth on both points or is it just my eyes... I can do a schematic and and realistic layout if you would like...

Actually it would be really nice from you.

I am starting to be a little puzzled. I bought this Gibson LP Studio new in 1997 in a shop whose dishonesty is not to be proven anymore (I learned this afterward... of course).
I got it for 6200 francs (~£620) instead of the 8000 francs (~£800) on the tag. I thought it was a current practice in a guitar shop but I am starting to wonder. What have they done with my Paul, before it was mine. From the serial, it has been built a year and four month before I bought it.

I personally never touched any wires on this guitar and it has never seen a tech before last May, when I had a setup @ sound control.

Your remarks quite surprise me. Do you think that this anomaly you spotted in the wiring can be the cause of my unefficient knobs?

I could pop it to a tech but I would quite like to do the work myself. The money meter is not at its highest and I really feel like I would benefit a lot from getting my guitars to play fine by myself, as a player.

 

[Amateur]

Re: Knob control issue

You should let us know what kind of pickups you have in your guitar, different pickup manufacturers use different color codes for their wiring.

 

[ErikH]

Re: Knob control issue

You should let us know what kind of pickups you have in your guitar, different pickup manufacturers use different color codes for their wiring.

From the pic in his first post it's pretty obvious that they are 2-conductor.

 

[Jazz Rock]

Re: Knob control issue

The pickups are the stock pups, 490R and 498T. I read on Gibson's
website that they are 4-conductor???

Now when I compare the cavity of my Epi and my Gibson, there is certainly
less wires in the Gibby than in the Epi. The Epi has 4 wires '59s with pull/push pots.

Now speaking of comparing both guitar and schematic. I was wondering if the wiring I got in the Epi was peculiar as it gives a nice twangy, bright sound when all the pots are on 10. Than if you turn back the volume to 9, you still got the power but with a more balanced sound. Finally if you turn the tone knobs gradually to 1, you got a nice gradation of sounds getting more bassy. But than when you are on 0, you got a really bassy sound. Kind of... the 10 and 0 position are quite strong whereas the position in between are more balanced and give a good gradation. Those it make sense to the naturally English speaking people that you are???

Anyway, I actually love this behaviour. Could I rewire the Gibby so to have a similar system?

 

[ErikH]

Re: Knob control issue

What value are the tone caps in the Epi compared to the Gibby? It could be just a simple change. I like .047uF for a tone cap myself.

There are less wires in the Gibby because the ground plane is the metal plate that all the knobs are mounted to and your pickups are 2-conductor. I had an LP Studio from the same time frame and they stock pickups were 2-conductor. Also, like you said, your Epi has dual 4-conductor '59s with push-pull pots. That'll add a few more wires right there.

 

[amputee]

Re: Knob control issue

eeee humble pie time... erik is right ... just need to check the pots for functionality took a glancing look at the picture ... what a plum I am... Is a good way to wire up the guitar I also like the use of the tag board just worry about oxidisation if thats the earth for the jack .... will slink off to the corner now...