NOBLE (dangit) pot wiring

[pabbi1]

Took a flyer on some of these. 4 pins, and marked as 204y50k

It seems like a really sweet pot, but we'll see. Question is, where to find wiring diagram (yeah, emailed the seller)? And, it is a 4 pin unit.

The oddity is, looking at the shaft side of the pot, pins up, is seems opposite the rk27, and... well, pins 1 is source and 2 wiper to get increasing resistance.

Allegedly, pin4 is a loudness pin, but how do I tell pin 3 is Ground for sure? I do notice that resistance decreases between pins 2 & 3 - is that right?

 

[luvdunhill]

Al:

Perhaps you posted an incorrect link? Your title references a Bourns pot.

The important thing here is there really isn't "source" "wiper" "ground". A potentiometer doesn't really know that it's being used as an attenuator, or really care.

I'd refresh your memory on how a standard potentiometer works (via Google, or find another one in your junk box and play with it) and then brute force the pins until you find analogs with the mystery device to your known device.

This is more or less what Tangent suggests in one of his tutorials and it's good advise. Once you understand how the general part works, it's easy enough to "pin-out" an unknown device.

this might help as well:

http://www.hificollective.co.uk/images/noble.pdf

 

[pabbi1]

Yep, backwards again. Thats why I ask... and struggle.

Bet you don't want to hear my question about a switched & fused IEC, huh?

 

[luvdunhill]

Quote:

Originally Posted by pabbi1 /img/forum/go_quote.gif Yep, backwards again. Thats why I ask... and struggle. Bet you don't want to hear my question about a switched & fused IEC, huh?

"backwards" doesn't hurt anything, give it a try

I'm up for IEC questions, shoot!

 

[MoodySteve]

The diagram that luvdunhill posted is correct.

I have some of the same pots that you have, but mine came with a Pinout Instructions sheet. From the sheet:

"The 'Not Connected' pins are just that - they make no internal connection. Noble used this pin for versions featuring 'loudness contour' or 'on-off' switch."

 

[pabbi1]

Quote:

Originally Posted by luvdunhill /img/forum/go_quote.gif "backwards" doesn't hurt anything, give it a try I'm up for IEC questions, shoot!

Pffft... I have plenty of wall sockets and meters - this one I can figure out eventually...

 

[spritzer]

Marc's diaphragm is correct for the normal Noble pots I've used.

 

[tangent]

Watch this: How a Potentiometer Works

 

[Steve Eddy]

Quote:

Originally Posted by luvdunhill /img/forum/go_quote.gif The important thing here is there really isn't "source" "wiper" "ground". A potentiometer doesn't really know that it's being used as an attenuator, or really care.

Just one caveat here.

It doesn't matter which end you use for input and ground if it's a linear taper pot. But it most definitely matters if it's a log or audio taper pot.

k

 

[tangent]

True, but the penalty is low: you just get reverse volume control. This is easy to diagnose, and the fix is also easy: swap the input and output wires.

 

[Steve Eddy]

Quote:

Originally Posted by tangent /img/forum/go_quote.gif True, but the penalty is low: you just get reverse volume control. This is easy to diagnose, and the fix is also easy: swap the input and output wires.

Aye, yes. Rotation would be an issue as well.

And the penalty there could get a bit expensive if someone has built a real scorcher of an amp and decides to check it out with a pair of headphones and the volume control turned fully counterclockwise thinking they had the volume turned all the way down.

Surprise!

k

 

[pabbi1]

Been there...

Now, since the seller was gracious enough to NOT include nuts with these beautiful units, anyone know where those can be sourced? The threads measure 9/32", but 5/16" (18) will not thread, as 18 is too coarse. Looks to be maybe 32 (or 28), but that is just a guess.

 

[Steve Eddy]

Quote:

Originally Posted by pabbi1 /img/forum/go_quote.gif Been there... Now, since the seller was gracious enough to NOT include nuts with these beautiful units, anyone know where those can be sourced? The threads measure 9/32", but 5/16" (18) will not thread, as 18 is too coarse. Looks to be maybe 32 (or 28), but that is just a guess.

Went digging through my junk box and found that I have one of those very same pots.

Near as I can tell, it's an M8 x 0.75 thread.

McMaster-Carr didn't have any 8mm nuts with that fine a pitch. But I did find an online guitar parts store that sells some cheapie pots with M8 x 0.75 nuts. Might want to buy a couple of those and neuter 'em.

Radio Shack may even have some cheapie pots with M8 x 0.75 nuts, though you'd have to open the packaging to find out for sure.

Good luck!

k

 

[sachu]

heh...I am starting at 5 of these beautiful NOBLE 204Y10k pots..

I don't know if they are superior to the PEC carbon which I like a lot..but will give it a shot sometime.