weird pot issue

G

Gish_85

New member
Both my volume and tone pots were acting like linear pots since I changed them... turns out they are log pots (checked them with a multimeter).
(By acting like linear I mean from 0-3 they go from full off to pretty much full on)

Anyone know whats happening. I checked the wiring and its all the right way round. I was thinking the pots could be antilog or something but I got them from a guitar shop so I figured it would be unlikely.

The pots say CTS500 0725 on the back in case that helps
I want to get a smooth continuous response from volume and tone controls does anyone have any suggestions?

I can't seem to get the diagram into the post but its a PRS with the 5 way selector

http://www.prsguitars.com/csc/schematics.html
(The pre-2007 wiring)

Thanks!
 
Re: weird pot issue

loose ground on your volume pot is what I would suspect

as both are doing it

if the ground on your volume pot were missing
your volume would go down then right back up ( like a tone knob )
because the pot has nowhere to shunt the signal to

if both are going from full off to full on in about a 1/4 turn then

some of the wiring is askew


but I'm just guessing

EDIT
Ya know I had the same trouble with a tone pot here a month or so ago
I beleive what happened was one leg of the cap on the tone was shorting to ground before the cap
at the short leg to the terminal
I can't be sure but I redid it taped over the legs of the cap
and the problem went away
 
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Re: weird pot issue

Thanks for the reply. You are probably right about wiring but its not the grounding, just checked with the ol multimeter and everything (tone, vol, bridge, jack) is connected.
 
Re: weird pot issue

nah its not that either, theres plenty of space and no uncovered wires anywhere near the cap. Lame
 
Re: weird pot issue

well on the pots
the outside terminals
think of those as one large coil of wire
the center terminal
is a wiper that moves along this coil and references back resistance

T-------000000000000000----------T
^here to^
T-------000000000000000----------T
^here to here^
T-------000000000000000----------T
^or here to here^

on the volume one outside terminal is to ground
as mentioned earlier
on the tone one outside terminal is left unused

if by chance the unused tone terminal was grounded
it may do something unexpected

we've already covered what an ungrounded volume pot does

if by chance, and I'm sure this isnt the case, you grounded the wiper of the volume
it would act strangely

could you supply a photo of the control cavity?

EDIT
the suddenly on isnt a function of linear or audio pots

the example I gave

T-------000000000000000----------T
^or here to here^

is an example of a linear pot
if I could have made the upper part arch it would have represented and audio or logarithmic taper

in linear
a 500k pot turned half way thru its ( I cant remember what thats called but halfway ) should read 250k
a 500k audio will read 250k about 75% thru

hmmm
maybe your right they are audio pots
 
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Re: weird pot issue

yeah the pot was reading under 100k at half way, and went up to 480k ish. Didn't check where it hit 250 though
 
Re: weird pot issue

dang
well I cant see the photo

try this
select the photo with a RIGHT click
move down to where is says
"Copy image location"
select that
come back here and in the
QUICK REPLY at the bottom of thread
you will see a yellow button that has mountains on it
select that
paste image location into the box that pops up
select ok

should post the image

on Photobucket.com
naviagating to the album and select a picture
in one corner it has all the selections pre arranged for posting
even includes the"
IMG ]"
 
Re: weird pot issue

sounds like an audio pot to me
even its behaviour now that I thinka about it sounds like an audio pot
I prefer linear pots for volume

I think I know what happened

does the hot in from the jack come to one side terminal or to the center wiper terminal?
 
Re: weird pot issue

Ah k thanks for that. I'm not sure exactly what you want to see so let me know if this doesn't cover it

4580352168_832862138e_o.jpg

4579719325_ec65ffb063_o.jpg

4580350646_0e90b3c6db_o.jpg
 
Re: weird pot issue

if you got a pair of dikes handy
clip that leg from the treble bleed in the last photo
it seems to be coming awful close to the pot body
and could ground out

no not those dikes,
side cutters, diagonal cutters
 
Re: weird pot issue

hmm
is that a braided ground running round there?

well I just don't see anything else
it looks like a fine, neat job you've done there
 
Re: weird pot issue

yeah that cap does look pretty treacherous in that photo.
Cheers, looks like i'll be needing different pots
 
Re: weird pot issue

oops

"well I just don't see anything else
it looks like a fine, neat job you've done there "

Cheers, looks like i'll be needing different pots

Thanks for your help dude
 
Re: weird pot issue

just for posterity, realized I was being an idiot, the reason for what was happening was my treble bleed capacitor! Took it out and everythings fine now
 
Re: weird pot issue

if you want an actual volume difference on every number of the volume knob you should check out the "Superpot" from rsguitarworks.net. by far the best pot i have ever used. i now have them in all my giging guitars and couldn't be happier. definately worth the price.
 
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