I'm trying to replace the poteniometers 1no Volume and 1no Tone on a 1970s Sonorama M390 vintage record player.

Im struggling to find the right components, or even where to start with this. (few images included below)

Volume: 1M Ohms B (as printed on the component), I'm unsure what Wattage this will be for a replacement part.
Tone: 2K2A (as printed on the component), I have no idea what this means.

Having tested the current on both potentiometers, the volume one seems fine but there's no current running through the tone. If I'm going to replace the once I may as well replace both.

Please could someone give me advice as I literally have no idea whats going on and I'm really struggling.

 

Hello,

The 1M B is a linear potmeter.
The 2K2 A is an audio taper (log) potmeter.



https://eepower.com/resistor-guide/resistor-types/potentiometer/

Are both sections of the potmeters on the same axis?
If so they are stereo potmeters.

This page will tell you more about potmeters:
https://www.circuitstoday.com/potentiometer

Bertus

 

The 1M B is a linear potmeter.
The 2K2 A is an audio taper (log) potmeter.

That seems the wrong way round. The 1M is for volume (per TS) and the volume pot I would expect to be log taper.

 

Having tested the current on both potentiometers, the volume one seems fine but there's no current running through the tone. If I'm going to replace the once I may as well replace both.

If you have a multimeter, with the power off, connect the meter between one end connection and the centre connection. The measured resistance should change smoothly between zero and the pot value (1M or 2.2k). Repeat this measurement centre to each end for each section of each pot.

 

1Meg log, and 2.2K Lin , 1/4W pots..

 

I would clean them before going through the work of replacing them.

 

That seems the wrong way round. The 1M is for volume (per TS) and the volume pot I would expect to be log taper.

I have it wrong. Looking at the pictures, the 2k2a is the volume and the 1M is the tone. Which then makes sense what Bertus says..

 

1Meg log, and 2.2K Lin , 1/4W pots..

1/4W pots .. thats exactly what I was looking for. Would it be 1M Lin, and 2.2K Log if as per the pictures the 2K2A pot is infact the volume and the 1M Ohms B is the tone?

Volume = Log
Tone = Lin .. ?

 

Are both sections of the potmeters on the same axis?
If so they are stereo potmeter

They are both wired onto the top three terminals of each pot? .. not sure if this means theyre on the same axis. It is a mono record player with only one speaker don't know if this has anything todo with the pots being stereo or not

 

Hello,

On a stereo potmeter both sections are moved by one axis:



On a dual potmeter the sections can be moved independend by the two axis that are over each other:


The thin axis will move the back potmeter.
The copper colored axis will move the front potmeter.


Bertus

 

Hello,

On a stereo potmeter both sections are moved by one axis:

View attachment 216309

On a dual potmeter the sections can be moved independend by the two axis that are over each other:

View attachment 216308
The thin axis will move the back potmeter.
The copper colored axis will move the front potmeter.


Bertus

In that case to answer you're question from earlier -Yes they're both fixed on the same axis as the first picture shows.

 

I have it wrong. Looking at the pictures, the 2k2a is the volume and the 1M is the tone. Which then makes sense what Bertus says..

Ok , 1Meg Lin and 2k2 log..