Atmegatron: Potentiometer (distortion)

[rio]

Hi paul,

Can you tell me which potentiometer is used for the distortion (which is on the far right)?
That Potentiometer is scratching a bit with me. Maybe I like to replace it.

Is it "Logarithmic" or "Linear"? Please, can you tell me the resistance value, the shaft-height in mm, the type (pin count, identification/product/model number)?
thank you.

Greetings,
rio

[paulsoulsby]

Hi,
The spec is:  10k, linear, 6mm diameter, D shape, 25mm height. 
I think Bourns and Alps both make one. 
Possibly worth a bit of contact cleaner first?

[rio]

ok thx.

greetings,
rio

[rio]

I think ALPS RK09D1130C2P should fit.

The 6 potentiometer at the top are all the same, right?
What are the "values/parameter" for the volume and boost potentiometers?

Greetings, rio

[paulsoulsby]

oh - no 3 of them are different.  You'll see they are bigger.  Here's the part:  Alps RK12L12C0A0E

The bass boost pot is 1k:  Bourns PTV09A-1025F-B102
Rest are 10 k.

[rio]

ok, it looks like they are: "Cutoff", "Reso", "Filter LFO":



1. So can I use "Alps RK12L12C0A0E" as a replacement? - they have 15A taper -> they are logarithmic - Are you sure? I ask, because the 3 others are linear.

2. For the boost poti: I don't find Bourns PTV09A-1025F-B102  --> only PTV09A-4225F-B102 (can I take these as replacement therefor?)
they are linear, right?

PS: With that middle number 1025F, I can only find these "logarithmic" ones: "PTV09A-1025F-A203" <--- but these are not the right ones, right?

Please, I need more details about these both potentiometer types...

Greetings,
rio

[paulsoulsby]

1) Yes these 3 are definitely logarithmic.  The others are linear
2) The codes are explained in the datasheet: https://www.mouser.co.uk/datasheet/2/54/tv09-777818.pdf
The 4 in "4225F" means that there is no sleeve to the pot, so it will wobble (some early units actually have this type, because I could not get stock of the other type)
The first 2 in "4225F"  means that there is a centre detent.  There isn't any need for a centre detent with any of the pots.  You use a detent when middle = 0 (but the Atmegatron only uses anti-clockwise = 0).
So technically and electrically PTV09A-4225F-B102 is fine, by you may find the differences annoying!

PTV09A-1025F-A203 will not fit the logarithmic pot holes.  They must be "dual gang" with 6 pins.

[rio]

ok thanks, for your great explanation...