PL2000 S2 Balance pot.

[George S.]

Need to replace mine. I see two part#s listed in the manual. One is a 50k non linear dual gang, the other is a 100k linear I assume is single gang. I have the 50k dual gang which I assume is audio taper, or would it be logarithmic? Guess I need to pull it and measure resistance at each clock position to know for sure.
For a 50k dual gang balance pot, is the taper really critical?
And what about the 100k linear that's listed, I'm not understanding this one.

 

[Wheel-right]

You might check with Ed, oldphaser on this as he may possible have an original.

 

[Gepetto]

Balance pots are normally linear...

 

[MarkWComer]

Need to replace mine. I see two part#s listed in the manual. One is a 50k non linear dual gang, the other is a 100k linear I assume is single gang. I have the 50k dual gang which I assume is audio taper, or would it be logarithmic? Guess I need to pull it and measure resistance at each clock position to know for sure.
For a 50k dual gang balance pot, is the taper really critical?
And what about the 100k linear that's listed, I'm not understanding this one.

I think audio taper by nature are logarithmic. I noticed that the front panel sensitivity pots are specified as linear in the service manuals of the 400/700 S2, so I’m a bit confused. I once theorized that balance controls didn’t attenuate until the 12 o’clock position, opposing tapers by channel. Far too many of my suppositions and theories have fallen flat through the years, though.

Another theory here:

 

[George S.]

Thanks guys, good info. Really don't want to replace it with same as want to upgrade. Found 3 candidates, all linear, one mil-spec but pricey. Going to break out the calipers this weekend and measure. Solid shafts, shouldn't be too hard to make D shape.

 

[George S.]

I have the Monty Python box set on DVD, good stuff. My favorite is Bicycle Repair Man. My early career.

 

[marcok]

Need to replace mine. I see two part#s listed in the manual. One is a 50k non linear dual gang, the other is a 100k linear I assume is single gang. I have the 50k dual gang which I assume is audio taper, or would it be logarithmic? Guess I need to pull it and measure resistance at each clock position to know for sure.
For a 50k dual gang balance pot, is the taper really critical?
And what about the 100k linear that's listed, I'm not understanding this one.

Why do you want to replace pot ?
Generally it's sufficient to deox it.
The pot mounted in PL 2000 has no center position and so at 12 o'clock one channel
could be higher than the other one . If this is your issue you can compensate the tracking error
with a resistor connected in parallel on the lower leg .
I did this on my Dynaco Pat 4 preamp .
Remember that this is a D shaft type and probably it's not so easy to find it.
Ciao
Marco

 

[marcok]

I think audio taper by nature are logarithmic. I noticed that the front panel sensitivity pots are specified as linear in the service manuals of the 400/700 S2, so I’m a bit confused. I once theorized that balance controls didn’t attenuate until the 12 o’clock position, opposing tapers by channel. Far too many of my suppositions and theories have fallen flat through the years, though.

Another theory here:

Only volume pots must be logarithmic .
https://en.wikipedia.org/wiki/Equal-loudness_contour
All attenuators generally are linear.
In any case every linear pots can be easily modified to become log or anti log
https://www.google.it/search?q=turn...VEyqQKHRRHDiEQ_AUoAXoECAEQAw&biw=1366&bih=584
For example the volume pot of PL 4000 is linear with 2 resistors connected between gnd
and center pin .
Ciao
Marco

 

[George S.]

It's totally unbalanced looking at the two channels on the scope. Clocked to two o'clock it's best. Been cleaned with Deoxit many times and lubed with Deoxit fader grease. Think it's just a low quality pot. Bugs me.

 

[George S.]

Mark C., PL Repair Man! Or how about those mountain climbers climbing the sidewalk?

 

[George S.]

Only volume pots must be logarithmic .
https://en.wikipedia.org/wiki/Equal-loudness_contour
All attenuators generally are linear.
In any case every linear pots can be easily modified to become log or anti log
https://www.google.it/search?q=turn...VEyqQKHRRHDiEQ_AUoAXoECAEQAw&biw=1366&bih=584
For example the volume pot of PL 4000 is linear with 2 resistors connected between gnd
and center pin .
Ciao
Marco

Hey Marco, great info! Thanks for the links!

 

[marcok]

It's totally unbalanced looking at the two channels on the scope. Clocked to two o'clock it's best. Been cleaned with Deoxit many times and lubed with Deoxit fader grease. Think it's just a low quality pot. Bugs me.

Add a resistor . To find the right value use a 220 KOhm pot and measure .
It's the typical issue . At that time center snap pots probably did not exist or they were expansive
See my Dynaco PAT 4 . ( I had a 2dB tracking error ) Only one resistor to fix the problem.

Ciao
Marco

 

[Gepetto]

Adjust the pot for channel balance. Loosen the securing nut and rotate the pot so the knob dot lines up with center. Retighten the nut.

Does not work for those with OCD but it works

 

[George S.]

Adjust the pot for channel balance. Loosen the securing nut and rotate the pot so the knob dot lines up with center. Retighten the nut.

Does not work for those with OCD but it works

Yeah, I have a case of OCD. Going to change out that pot and post the part# for those likewise afflicted. Thanks everyone.

 

[MarkWComer]

Yeah, I have a case of OCD. Going to change out that pot and post the part# for those likewise afflicted. Thanks everyone.

Right... That wouldn't sit well with me, either...

 

[MarkWComer]

I have the Monty Python box set on DVD, good stuff. My favorite is Bicycle Repair Man. My early career.

I bought a used set from ebay, but disc 10 was missing- the one with Anne Elk, yet! I still have the episode from WETA 26 ripped to .mkv from an old VHS tape.

 

[Gepetto]

Yeah, I have a case of OCD. Going to change out that pot and post the part# for those likewise afflicted. Thanks everyone.

PDA241 HRT02 104B0 is the pot you want. Nice feel Bourns pot.

 

[Gepetto]

Yeah, I have a case of OCD. Going to change out that pot and post the part# for those likewise afflicted. Thanks everyone.

George
Let us know if it takes selecting through more than one to find a satisfactory pot. The halfway point of a pot is not specified mechanically

 

[George S.]

I bought a used set from ebay, but disc 10 was missing- the one with Anne Elk, yet! I still have the episode from WETA 26 ripped to .mkv from an old VHS tape.

On the road working until this Saturday evening. When I get home I'll check for that disc I'm sure I have, try to rip it for a "personal backup". If successful I'll PM you for your address.

 

[George S.]

PDA241 HRT02 104B0 is the pot you want. Nice feel Bourns pot.

According to Mouser, that's a 100k single gang. Can't decode the specs right now due to time and smart phone. I was thinking that the only way a single gang 100k would sub for a 50k dual gang is if the single gang had 2 wipers and 6 solder lugs. Last week I did go to the Bourne's website and configured a 50k dual gang plain shaft pot, but couldn't find that part# anywhere. Also tried some variations, no luck. Did find two Bourne's dual gang that might work on Mouser or Digikey. Can't recall the numbers was just looking.
I fail to understand how a 100k single gang can sub for a 50k dual gang. But the manual lists one.