Replacement problem for Goodrich Pot

ajm · From: Los Angeles

I recently ordered some pots from Newark for my passive Goodrich pedal.

I thought I was very careful when taking the old pot out to note down how things went. I had a devil of a time with the new pot, though. It seems that the string would slip and the pot setting would gradually move away from the full off setting when using the pedal.

I finally found a method that seems to work for winding the string, but what is the right way to do this?

Also, I noticed that the pots I got from Newark had a little more rotation that the old pot. That is, they turn a little closer to a full circle than the old ones. I ended up setting the new one to full off one way, which gives it about 80-90% voltage in the full on position. This probably doesn't matter much to the ear, because 80-90% on a linear pot is about equal to a volume of 9.5 out of 10 on an audio taper pot.

By the way, the pot works well and is quiet.

Any thoughts/instructions would be appreciated.

Steve Feldman · From: Central MA USA

AJM -

I don't know if there is a way to get these rascals to come both full on AND full off at the same time. It's usually a case of either/or. I run my string through beeswax and then wind it 2-3 times around the shaft and that usually does it. I also usually go for the volume and live with a slightly open pot at the 'off' position. My preference, anyway.

Bill C. Buntin · Posted 31 Dec 2001 5:04 pm

I think it better to have the pot go to zero ohms (Full on) rather than full off and some resistance when you reach full travel. That way the pickup gets to load up all the way. I'm sure there is a more eloquent way to say this, but thats' the way I wind mine when I replace them.

Bill Moore · From: Manchester, Michigan

Scotty has instructions for installing the string on his web site. Here is the link: http://www.scottysmusic.com/info/goodrichstring.htm I also think it's best to have it rotate to full on, rather thanpartly on.

Cairo Zoots · Posted 31 Dec 2001 7:43 pm

AJM-"Changing the Pot in the Volume Pedal
Written by Jeff Newman" is a pretty good source for doing it right.....go to.....http://www.steelguitarinfo.com/other/volumepedal/pot_change.html

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ree-00-dee-doo

ajm · From: Los Angeles

I knew that the Carter/Newman thing existed but couldn't find it when I looked for it. The Scotty's picture was just what I needed. Unfortunately I had to solve it on my own through a couple of days of trial and error. Thanks anyway, guys.

The main thing that the Scotty's picture seems to elude to is that you want as few winds around the shaft as possible. That makes sense to me, because I found that the string was harder to get tight and would tend to slip with more winds. The beeswax tip might help here also.

Here's a technical tip I got off of the 'net some time ago. I tried to get the website so I could post it here but it's no longer available.

The other thing I found were that the Newark pots were linear, not audio taper. (I got the part numbers off of a post here about a year ago.) I did not like this at all, because most of the apparent volume would happen at the early stages of pedal travel. It wasn't a gradual change.

As luck would have it, for some reason I ordered a 500K, 1 meg and a 5 Meg pot at the same time. (Probably to experiment with the effects of different loading.) I solved this problem by using the 5 Meg pot, and soldered a resistor equal to 20% of the pot value between the center terminal and ground. This changes the taper of the circuit to an audio taper which is IMHO much better.

So for a 500K load like the Goodrich comes standard, you'd need about a 3 Meg pot and a 600K resistor. As long as the pot is bigger than 3 Meg and the resistor you pick is 20% of the pot value you should be fine.

Thanks for the help. I thought someone may benefit from this tip.

Russ Wever · From: Kansas City

ajm,
You're correct in that there is no reason
for excessive turns of cord around the
shaft.
When I drew the illustration for Scotty
perhaps I should, for better clarity, have
indicated that the pedal is shown in
it's 'off' position.
When securing the cord to the 'tang', be
certain that it goes around the screw
clockwise so that when the screw is
tightened no cord-tension will be lost.
Also, it wouldn't hurt to deflect the tang
very slightly toward the shaft when
tightening the cord under the screw so
that a slight amount of tension will
be applied to the cord, eliminating any
potential slack.
Too much tension on the cord will cause
undue friction and premature wear in the
bushing of the pot.
~Russ

Bill Crook · From: Goodlettsville, TN , Spending my kid's inheritance

In all the pedals I have worked on, there is a threaded rod/screw/pin that will allow you to adjust the travel of the pedal itself. This wil allow you to setup the travel lenght of the pedal to the rotation degree of the pot. This results in a perfect 0 to 100% signal level. (Or at least the best of the pot)

These passive Volumne pedals arn't all that complicated,take a good look at it. Strings are allways wrapped in a clock-wise rotation,starting with a full "OFF position. Then 3 wrapes of the string, then pull tight,loop around the setscrew, or hook onto the spring to set the tension. On the rack and pinion units, simply adjust the travel of the moveable scetion. None of this applies to the electronic V/P . The varied setups of these pedals are often not dependant to the travel of a pot or trimmer.

[This message was edited by Bill Crook on 03 January 2002 at 06:16 AM.]

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