Frying Pan Guitar - Need R value for Pot

[mpm]

Does anyone happen to know the potentiometer value used in the
Rickenbacher "Frying Pan" electric steel guitar? Or a website that I
might be able to find this value?

My brother has one of these electric guitars (the first electric model
ever produced I'm told, though he has the 1946 edition - the earlier
ones did not have a volume control...)? His pot is noisy and also
has a broken knob, so I offered to install a new one.

I did not have a meter with me to measure it's resistance (which might
have been problematic anyway as it is very worn?), and it was not
marked, or at least not anything I could see. I am assuming it is a
linear taper pot, but I really don't know. It looks like a regular
1/4-inch single turn pot. Thanks! -mpm

 

[mpm]

Radio shack has meters for less than $10.

If the pot is just noisy, then you should be able to measure it's
resistance just fine.

You'll probably want to go to a guitar shop to get a pot and a knob;
they may be able to tell you the value, although you want the meter anyway.

--

Tim Wescott
Wescott Design Serviceshttp://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" gives you just what it says..
See details athttp://www.wescottdesign.com/actfes/actfes.html- Hide quoted text -

- Show quoted text -

Thanks Tim, but I already knew all that.

I have several Fluke meters, all of which were back at the shop (in
another city), so obviously NOT available to me at the time. And I'm
not going to buy any Radio Shack $10 meters. Frankly, I have enough
aggrevation in my life than to deal with that....!!

It's a very famous guitar. Somebody will have the answer.

-mpm

 

[Mycelium]

Does anyone happen to know the potentiometer value used in the
Rickenbacher "Frying Pan" electric steel guitar? Or a website that I
might be able to find this value?

My brother has one of these electric guitars (the first electric model
ever produced I'm told, though he has the 1946 edition - the earlier
ones did not have a volume control...)? His pot is noisy and also
has a broken knob, so I offered to install a new one.

I did not have a meter with me to measure it's resistance (which might
have been problematic anyway as it is very worn?), and it was not
marked, or at least not anything I could see. I am assuming it is a
linear taper pot, but I really don't know. It looks like a regular
1/4-inch single turn pot. Thanks! -mpm

What? No ohmmeter? You would still get a proper reading since the
scratchyness is related to wiper contact, so the full span reading should
still be viable. If it were not, the circuit would not work at all.

To determine if it is linear or audio taper, you should be able to take
readings at a few point throughout the rotation, and plot them to see the
taper, if any.

 

[Mycelium]

Thanks Tim, but I already knew all that.

I have several Fluke meters, all of which were back at the shop (in
another city), so obviously NOT available to me at the time. And I'm
not going to buy any Radio Shack $10 meters. Frankly, I have enough
aggrevation in my life than to deal with that....!!

It's a very famous guitar. Somebody will have the answer.

-mpm

Yeah... like a decent guitar shop or music chat forum.

 

[Eeyore]

Yeah... like a decent guitar shop or music chat forum.

Plenty of guitar groups on Usenet.

Graham

 

[Martin Griffith]

On Sat, 21 Jun 2008 12:22:18 -0700, in sci.electronics.design Mycelium

sniiip

To determine if it is linear or audio taper, you should be able to take
readings at a few point throughout the rotation, and plot them to see the
taper, if any.

Nah set the pot to central, see if the left side = the other side


martin

 

[mpm]

�What? �No ohmmeter? �You would still get a proper reading since the
scratchyness is related to wiper contact, so the full span reading should
still be viable. �If it were not, the circuit would not work at all.

Actually, only two leads are connected (wiper and one end), so knowing
the full-open isn't all that helpful, and even if the other end were
open it would still work.

I am amused by all the comments & suggestions that on the surface,
would seem to suggest I don't know how to use a meter, or how to
measure an unknown pot value, or even that 65 year old (+/-)
mechanical parts exhibit noise. For the record, I was up for my
father's funeral and did not bother to pack a voltmeter. (I know, the
true sign of a nerd if ever there was one. Well, that and pocket
protectors. But I digress...)

While there, my brother asked me to look as his lapsteel guitar. We
took the back off, it looked like a standard pot, unmarked, and that
was the end of it. Mistakenly, I thought that since this was supposed
to be a very famous guitar model, it would be a snap to locate the
replacement value online. So far, I have heard recommendations for
everything from 10K to 250K, both linear and audio tapers. (In short,
nobody seems to know.)

Add to this, the US Patent Office does not seem to have the schematic
scanned. (#2089171).
Bummer. I can always do in the hard way... (measure voltages off
the pickup, and select value from there - though it would be nice to
have the parts handy next time I'm home and not have to wait on their
subsequent arrival.) But thanks for the help.

-mpm

 

[Mycelium]

Actually, only two leads are connected (wiper and one end), so knowing
the full-open isn't all that helpful, and even if the other end were
open it would still work.

If it is being used in rheostat mode (it is), then you can use virtually
ANY value high enough to attenuate the output to the desired "zero"
level. Then, working toward zero ohms on the "stat" takes you toward max
output.

Rheostat choice here is no brainer. A nice one or two turn wire wound.
I'd start with a 50K and reduce value of pot till your amp starts to pick
up the output jack signal, then read the pot for the value ballpark.

Likely less than 10k.

 

[Mycelium]

I don't recall anybody inferring that you don't know how to use the meter, but
it's becoming increasingly more obvious that you don't.

Yes, he does. If you had read a bit, you would have noted that he has
several very expensive meters. Perhaps he can even read one better then
you.

What he may be doing is assuming that a noisy pot would give an
improper reading across its end to end terminals.This is generally not
the case, but I can see where a completely scratched up, OLD OLD style
and technology pot could gain resistance value if some of the pot
resistance medium was scratched off.

What one would gain is a ballpark figure for the pot.

Since he stated that it is hooked up in rheostat mode, it will be easy
to arrive at a sufficient value to solve his needs.

At least he knows how to make a proper post in Usenet. That shit news
reading client you are using cannot quote properly, OR you were so stupid
that you went into the settings and made the quote character a blank
field.

 

[mpm]

Maybe you can explain why it isn't possible to measure the pot's resistance with
an ohmmeter? � And what is your procedure for measuring the voltage from the
pickup and arriving at the pot's value?

I don't recall anybody inferring that you don't know how to use the meter, but
it's becoming increasingly more obvious that you don't.

Dave,
Get a life.
The damn thing is nearly 70 years old, and in really bad shape.
I wouldn't trust any reading it gave me anyway, even if that reading
were correct.

I wish I had a photo of it, then you'd understand.
QUIT thinking this is some pristine part out of a Digikey order. It
is not.

Yes, I could have measured it - but I did not have a meter with me.
What is so god-damned difficult about understanding that very basic
fact?

And **** you anyway. Seriously.
It is becoming increasing obvious (to me) that you can't understand
what I previously posted.
This was never about how to measure a pot. That is basic electronics
101.
All I wanted was the value, and if you don't know it, then just shut
the **** up.

As for your comment that a direct measurement is the "easiest,
quickest and most reliable method...." Possibly, if you count the
$140 in gas, and the 10 hours on the road it would take me to actually
get back to the guitar with meter in hand. And of course, even that
would assume that the device in question had never been replaced by
previous owners over the past seven decades. I think you make way too
many assumptions here!

Respectfully, (to the extent I can be after a post like yours..)
-mpm

 

[mpm]

�If it is being used in rheostat mode (it is), then you can use virtually
ANY value high enough to attenuate the output to the desired "zero"
level. �Then, working toward zero ohms on the "stat" takes you toward max
output.

�Rheostat choice here is no brainer. �A nice one or two turn wire wound.
I'd start with a 50K and reduce value of pot till your amp starts to pick
up the output jack signal, then read the pot for the value ballpark.

�Likely less than 10k.

Thanks.
That sounds about "right".
This is a very, very early pickup design.
Cutting edge at the time, involving a pair of horseshoe magnets.

I am probably just going to order a small assortment of pots (luckily,
it appears to be a 1/4" shaft variety...) One of them will be
"close enough". It's not about the dollars, it's about being able to
fix it next week when I'm up there again. Regardless, any pot is
going to better that what's in there now, but it'd be nice to get it
right.

-mpm

 

[mpm]

� What he may be doing is assuming that a noisy pot would give an
improper reading across its end to end terminals.This is generally not
the case, but I can see where a completely scratched up, OLD OLD style
and technology pot could gain resistance value if some of the pot
resistance medium was scratched off.

...For that matter, there's really no guarantee that there is end-to-
end conductivity.
It is totally possible, though I agree unlikely, that the far end of
the pot has no conductivity to the far terminal. But the question as
to whether or not this is even the original pot is still there, which
is one of the (unspoken) reasons I was asking in the first place.

Absent a definitive answer, my current "plan" is to acquire a 10K, 50K
and 250K and see what shakes. (hopefully, not literally.) Ha!!


-mpm

 

[mpm]

Naa, he's an engineer, so he's too cheap to buy a meter at Rat Shack for
a one-time job.

He just hasn't thought that he could leave it in his glove box for those
'just in case' moments

Sorry Tim, No more room in the glovebox. (Too much Viagra in there
already!!).
Let's see that get through Jim's filters.....

Actually, it reminds me of a joke:

A lady goes into the Pharmacy and starts to ask about Viagra.
Woman: Does this stuff actually work?
Druggist: Oh sure. It's works really well!
Woman: That sounds great. Can I get it over the counter?
Druggist: Well yeah, if I take two......

-mpm

Actually, I have no idea what is in my glovebox. But I do know I have
a couple of spare, new, 8-pin RS-485 transceiver chips I ordered in
there somewhere that go to our church's Strand lighting
controller.... Does that count??

Might make for a curious "inventory experiment" next time I'm in the
mood.

 

[mpm]

Apologies to the OP... �I should have been more polite.

Apology accepted. So please ignore my last post.

I use Google Groups to post, (which I understand is the worst ever).
Character substitutions do not bother me. Character assinations do.
Plus, I'm in a major funk anyway I guess. I usually just let the
comments roll off....

Mental note to self. Do not post late at night.

-mpm

 

[Mycelium]

...For that matter, there's really no guarantee that there is end-to-
end conductivity.

Yes... given the way you said that it is hooked up, there is no
guarantee. Good observation.

It is totally possible, though I agree unlikely, that the far end of
the pot has no conductivity to the far terminal. But the question as
to whether or not this is even the original pot is still there, which
is one of the (unspoken) reasons I was asking in the first place.

Absent a definitive answer, my current "plan" is to acquire a 10K, 50K
and 250K and see what shakes. (hopefully, not literally.) Ha!!

Yeah... someone even mentioned 500k. Dial down till you start hearing
it and take a reading.

 

[JosephKK]

Actually, only two leads are connected (wiper and one end), so knowing
the full-open isn't all that helpful, and even if the other end were
open it would still work.

I am amused by all the comments & suggestions that on the surface,
would seem to suggest I don't know how to use a meter, or how to
measure an unknown pot value, or even that 65 year old (+/-)
mechanical parts exhibit noise. For the record, I was up for my
father's funeral and did not bother to pack a voltmeter. (I know, the
true sign of a nerd if ever there was one. Well, that and pocket
protectors. But I digress...)

While there, my brother asked me to look as his lapsteel guitar. We
took the back off, it looked like a standard pot, unmarked, and that
was the end of it. Mistakenly, I thought that since this was supposed
to be a very famous guitar model, it would be a snap to locate the
replacement value online. So far, I have heard recommendations for
everything from 10K to 250K, both linear and audio tapers. (In short,
nobody seems to know.)

Add to this, the US Patent Office does not seem to have the schematic
scanned. (#2089171).
Bummer. I can always do in the hard way... (measure voltages off
the pickup, and select value from there - though it would be nice to
have the parts handy next time I'm home and not have to wait on their
subsequent arrival.) But thanks for the help.

-mpm

My best guess is 50k or 100k log taper. And it is exactly that, a
guess; but typical for then normal "Hi-z" audio equipment.