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teegar

idiot in need of wiring help, please

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So I'm on the verge of soldering my way into trouble with the Wilshire reissue upgrade. All new pots, switch, jack, and of course minihums. A few dilemmas I hope you folks can straighten me out on.

 

1) Seymour Duncan wiring shows the tone cap soldered to the back of the tone pot, while Stew Mac shows the cap soldered to the volume pot grounded lug. No difference I assume, any advantage either way? (See pics below)

 

2) Stew-Mac alternate control wiring shows that if the pickup and wire to tone pot come in on the middle (wiper) lug, and output to switch on the end, this will allow independent volume control when both pickups are on in the middle switch position. Does this work as advertised? This will sound very naive, but as you turn the volume pot down, if the signal is coming in through the wiper, couldn't it travel in either direction, would you be losing more to ground than other wise if the pickup output were on the end lug?

 

3) Finally, the S-M wiring kit gives you a good length of shielded coaxial cable to connect switch to pots and jack, rather than a shielded 4-wire (which would be easier). I almost dread sending 3 lengths, from bridge volume and neck volume pots, and jack, to the switch; and then how best to ground? Should I send a plain old unshielded wire from the switch ground to the back of a pot? What about the shielding in the coaxial, does each shield need to also be grounded? Seems like there won't be any room on the back of pots for all this grounding! Do I need to bite the bullet and just get some 4-wire (and if so, why doesn't Stew-Mac put THAT in their wiring kits?)

 

Really appreciate any thoughts, pics below.

 

sdwiring.jpg

 

smwiring.jpg

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I'm an idiot when it comes to wiring as well, I do know the difference between the two capacitor configs, though.

 

The SD configuration is the "modern" way of wiring a tone pot. When the volume is rolled off it results in a loss of tone.

 

The Stew Mac is the "50s" style wiring. This method retains the tone when the volume is rolled off.

 

That's basically the gyste between the two. I'm sure some of the more experienced members will be able to chime in.

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So I'm on the verge of soldering my way into trouble

with the Wilshire reissue upgrade. All new pots' date=' switch, jack, and of

course minihums. A few dilemmas I hope you folks can straighten me

out on.

 

1) Seymour Duncan wiring shows the tone cap soldered to the back

of the tone pot, while Stew Mac shows the cap soldered to the volume

pot grounded lug. No difference I assume, any advantage either way?

(See pics ABOVE)

 

2) Stew-Mac alternate control wiring shows that if the pickup and wire

to tone pot come in on the middle (wiper) lug, and output to switch on

the end, this will allow independent volume control when both pickups

are on in the middle switch position. Does this work as advertised? This

will sound very naive, but as you turn the volume pot down, if the signal

is coming in through the wiper, couldn't it travel in either direction, would

you be losing more to ground than other wise if the pickup output were

on the end lug?

 

3) Finally, the S-M wiring kit gives you a good length of shielded coaxial

cable to connect switch to pots and jack, rather than a shielded 4-wire

(which would be easier). I almost dread sending 3 lengths, from bridge

volume and neck volume pots, and jack, to the switch; and then how

best to ground? Should I send a plain old unshielded wire from the switch

ground to the back of a pot? What about the shielding in the coaxial, does

each shield need to also be grounded? Seems like there won't be any room

on the back of pots for all this grounding! Do I need to bite the bullet and

just get some 4-wire (and if so, why doesn't Stew-Mac put THAT in their wiring kits?)

[/quote']

 

 

I had to "shrink" your post for readability, it went all the

way across the page, making it a "booger to read"...

Following are just my thoughts, this might be a good lesson

to slap in the DIY thread if answers are satisfactory.

 

Question 1: Ground is ground - 2 diagrams, just soldered in different spot,

still ground, Cap still coming from "wiper lug" on tone knob. You are right,

no difference regarding tone contols.

 

Question 2: I wired both my EPI upgrades like the S. Duncan diagram, have not tried

the Independent Vol control Stew-mac version. Hoping someone who has tried/uses

this can jump in here... HOWEVER, I did find this, fron which perhaps we can both

learn - good explanation of both types of wiring!

 

http://www.stewmac.com/freeinfo/Electronics/Misc/i-4000/i-4000_4.html

 

Question 3: Have not seen what comes in a stew-mac kit, initially sounds like

overkill in the COAX cable??? Do you have a picture of the parts in the kit?

By COAX, you mean the BIG, FAT-@zz cable/like what you would wire your

home cable with? Shielding in cables should be grounded to do it's job,

but I'm scratching my head here...

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Thanks animal farm and JB - That 50's wiring looks OK, but I'm still wondering about where exactly the signal goes if the input (pickup output) goes to the wiper, and if the pot is at say 5, it seems to me the signal could travel towards the ouput to switch, and towards the ground, and so attenuate more to ground than if the input were on the end. [biggrin]

 

I was watching a vid with Dan Erlewine, who kept referring to the shielded cable as coax, so that's what stuck in my mind. This is what it looks like, compared to 4-wire.

 

wiret.jpg

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wiret.jpg

 

I understand now.

Yes' date=' if using the stew mac "coax", you'll run 3 wires, then solder the

"shields together, then jumper it over to Switch Ground pin. Definitely

make sure shield/ground don't touch "hot" parts of circuit (heat shrink,

electrical tape). The OTHER ends of the wire shields will be soldered to ground,

and center conductors will go to respective connections...

 

[b']OK, While looking at your Schematics, I just had a "BANG HEAD against WALL"

moment - came from remembering Military Electronics training.

MAJOR "D-u-u-u-h-h-h".....[/b] :D #-o #-o

 

Here's the deal with the WIRING at the pots:

 

***S. Duncan - pup input at tab 1, output to switch at tab 2 (WIPER)

 

The FULL electrical output of each pup is wired to each volume pot, then off to switch

via the wiper arm. The way this is wired makes it a PARALLEL resistance

electrical circuit. Huh?

In a parallel circuit, both "legs" mathematically combine to produce an output

LESS than the value of the lowest leg's resistance.

If I have 2 500K ohm resistors in parallel, the output of the circuit will be 250K ohms.

The lower the resistance, the more signal sent to ground, meaning less signal being

sent out to amp.

 

In the S.D. diagram, if you drop the volume of either pot with switch in MIDDLE position,

the overall resistance ouput value of circuit DROPS, sending more of BOTH pot signals to

ground, causing volume of BOTH pots to DROP.

 

***STEW-MAC Diagram Input on tab 2 (Wiper), output on tab 1.

 

Pic inserted for "Visualization Aid"!

4000_03.gif

 

Same thing as described above will happen to overall circuit, BUT, the way it's wired

into the WIPER allows you to vary the OUTPUT OF THE PICKUP at the point it's wired into

the circuit!!!!! The INDIVIDUAL VOLUME CONTROL comes from the fact that you're

controlling how much of the pickup signal is making it into the circuit! By controlling each

individual pup's input INTO the circuit, you're seperately controlling each pup's

VOLUME!!!!!!!!!

 

EUREKA!

 

Ehhhhhhh, make any sense??????

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Ehhhhhhh, make any sense??????

 

You're the best animalfarm. I finally got someone from stewmac on the phone and they assured me there really was no difference with wiring pickup to wiper or end lug, other than the individual control, so I'll go with it.

 

Thanks much for the help, I'll post with pics of my mess when it's done!

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These pics will include "as you go", too?

Would be great for documentation. There have been

similar requests in past for "what's the difference?", or

"why do both pup volumes go down in switch middle posit"?

 

Good luck!

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Teegar - gonna take an idea from your OP, create a new

topic regarding Vol pot wiring: Regular, and Independent Volume.

Question comes up occasionally, would be useful topic to put in

DIY Sticky. The info is actually in the Tech tip portion, but you've gotta dig for it.

Get around to it later tonite, I hope...

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