The King is tone deaf!

[Sowhat]

I've got a King… it's a bass guitar and it has the strangest problem I have ever come across, the tone control don't do anything. I looked at the wiring and it's all good, I've checked the pots which are both 500KA's and even swapped the tone one in and out with new 500KA's and 250KA's, I've tried caps from 10nf to 100nf, I even altered the wiring with the tone cap coming right off the pickup or right off the volume wiper and all with no change in the tone… I'm not getting any tone function period.

This bass uses 2 TV Jones Thunderblade pickups which measure about 4 to 4.2 killohms DC. These go to a Gibson style toggle switch who's output goes to one side of the 500KA volume pot, the other side goes to ground. The tone control originally came off the volume pot terminal the pickup feed was hooked to but I have tested it on the volume pot wiper as well, this volume wiper goes straight to the output jack. The tone pot is 500KA with one end being fed from the volume pot, the other end unhooked (open) and the wiper attached to a 33nf cap to ground, right now I have a 47nf cap in there.

Both the volume control and pickup switch work perfect but the tone control is D.O.A. … any ideas?

[Tom Phillips]

The photo is confusing. I don't see any tone cap and it looks like the bare wire soldered to the back of the tone pot could short to the center lug of the tone pot.

[J M Fahey]

Same here.
Please *draw* the actual schematic/wiring.
I see no tone cap and the tone pot seems to have only one lug connected (ground ), the wiper may or may not be touching a bare copper wire joining both pot grounds, blue-gray and dark grey wires prtly cover bottom pot body, etc., picture is somewhat fuzzy so I see shielded cables presumably coming from pots but not sharp/close enouugh to sparate center conductor from shield, etc.

Just draw it

[Sowhat]

Yeah guy's the picture stinks, all I have is an old G4 iPhone. The tone cap is there from the center terminal to the case of the tone pot, it's just so small it has disappeared in the picture but it's a good cap that measures out O.K. The wire that looks like it's shorting to the center pin is indeed close but there is no contact with the center pin of the tone pot. Although the wiring as far as interconnect is bare solid wire (weird!) it is all proper circuitry. I guess I can draw out the schematic but it will be identical to what you would expect from a proper circuit, this ain't rocket science. I was thinking about the impedance of the pickups versus the resistance of the pots and the value of the capacitor that is throwing this thing out of whack but that seems just silly... it's not a wiring problem this has been exhaustively examined already. Like I said, in over 1,000+ guitars that have come across my bench over the years, I have never experienced something this obviously impossible. Just as a side note I have subbed out everything except the pickups in this guitar a few times so far without any success in changing it's performance. Could it be the TV Jones's? Seems that's the only thing left, but how could they be effecting this, it just don't make any sense to me.

[rjb]

Notes:
1) Original wiring or not, I'd feel more comfortable if you'd put heat shrink over those bare interconnects.
2) That must be some tiny capacitor!
3) With DCRs of 4 to 4.2 kOhm, the pickups' inductance must be pretty low. But I would expect to hear some tone change with a 100nF cap.
4) I got nothin.

-rb

Edit: Maybe try a 1uF cap. What have you got to lose?

[Sowhat]

Here's some schematics I whipped up but I can't see how these can help. Here's how it came in the door...



This is an alternate wire up I tried as well...



Hey RJB, yeah that bare wire has to go but I want it to work first before I go pulling all the bare solid.

[olddawg]

The switch is different but look at the tone pot and cap value.

[Sowhat]

Hey olddawg, Yeah, I see that and 47nf is kind of standard as is 22nf or even 33nf depending on the pickup impedance, I have bins of them. The wiring is switched on the tone cap from the King but the net effect on the filter network (the pot and the cap) is the same... a cap to ground to bleed off high frequencies moderated by a variable resistor... a garden variety passive RC low pass filter. RJB suggested just what I was thinking about before I closed up the shop for the weekend and that's was to slap a 1uf cap in there... that's just crazy and you never ever see that but what the heck! I'm getting desperate, I hate things hanging around for days taking up valuable bench space.

[big_teee]

If that rig came through my piddle shop?
I would start by cleaning up the wiring, and use insulated colored wire.
I too see no tone cap!
I usually wire the tone pot directly to the jack output, or to the center of the volume pot. (50s style wiring)

T

[Sowhat]

I too see no tone cap!

It has a tone cap, it's had several tone caps, maybe when I shot this picture I was in between swapping out tone caps but believe me, it has a tone cap and it's in the right place in the circuit. This problem is only one of a host of problems with this bass. It came in with a wish list and I'm addressing issues one by one. I actually started by checking the truss rod and making sure it worked... no sense in doing anything if the truss is shot.

[big_teee]

It has a tone cap, it's had several tone caps, maybe when I shot this picture I was in between swapping out tone caps but believe me, it has a tone cap and it's in the right place in the circuit. This problem is only one of a host of problems with this bass. It came in with a wish list and I'm addressing issues one by one. I actually started by checking the truss rod and making sure it worked... no sense in doing anything if the truss is shot.

I believe you!
I get things like that from time to time.
Sometimes I just rip it all out and start over.
You'll get it!
I've been the Strat mechanic lately.
All things Strat! lol
Pickups, electronics, and partcasters.
T

[rjb]

I know you've got a lot more experience than me, but here's the only thing I can think of:
Are you absolutlely sure the cap isn't floating?
(Yes, I know the pots and caps tested good.)

I recently found out the hard way that many newer Bournes pots don't tolerate soldering temperatures over 500F.*
The carbon traces don't burn up, but the whatever-it-is substrate weakens.
In a while, the riveted legs loosen, causing intermittant or no connection between the terminals and the trace.

* The latest data sheets at Bournes' website specify a Soldering Condition of 260C max for 3 seconds max.
But who reads spec sheets for something as trivial as a pot?

-rb

[Sowhat]

Hey, RJB, good thought but I have checked that out and it is indeed connected (I shot some sine through it). I don't know about everyone but I run my iron at 750 degrees F. I'm lightning quick with it and naturally any 750 degree tips temperature drops like a stone once you touch it to a joint and sink the heat. I do everything from soldering pickup covers to the frames all the way to putting 0204 capacitors on a surface mount pattern and I never change my temperature... I guess it's really dwell time more than temperature that makes the day and with tiny SMD's not drinking too much coffee. :-)

[olddawg]

Hey olddawg, Yeah, I see that and 47nf is kind of standard as is 22nf or even 33nf depending on the pickup impedance, I have bins of them. The wiring is switched on the tone cap from the King but the net effect on the filter network (the pot and the cap) is the same... a cap to ground to bleed off high frequencies moderated by a variable resistor... a garden variety passive RC low pass filter. RJB suggested just what I was thinking about before I closed up the shop for the weekend and that's was to slap a 1uf cap in there... that's just crazy and you never ever see that but what the heck! I'm getting desperate, I hate things hanging around for days taking up valuable bench space.

My point is the high cut filter is the last thing before the jack. If you have a ground and the pot is wired correctly it has to work. I would redo it like this.

[Sowhat]

My point is the high cut filter is the last thing before the jack.

If you saw the two schematics I posted then you know that I tried that configuration with "alternate king wiring" and it made no difference. Thing is, I don't ever remember seeing 4KDC pickup windings before, more like 8KDC or even 14KDC. I think this has something to do with the filter not being in range with standard value caps. I have no indication that this tone control ever worked since the bass was new... maybe a design flaw? Tuesday morning I open up the shop for the new week and I'm going for broke with a 1uf cap and see what that does... I'll keep you posted.