Potentiometer Question

[Les Dickson]

• I’m working on a Rogers Majestic R221 and I’m puzzled by the volume control.
• I suspect the switch portion is broken because when the radio is on and working if I turn the knob counterclockwise to turn the radio off the knob continues past the normal stop point.
• I haven’t opened the unit up to physically inspect it.
• It’s a type of potentiometer I’ve not worked on before because it appears to have two wipers if I’m reading the schematic properly.

So my main question is what do I specify when ordering a new potentiometer with a switch.
In the attached photo the white arrow shows the location of the second wiper.
I’ve also attached a section of the schematic

Attachments:

1. 

   switch-pot-R221.jpg
   

2. 

   switch-volume-CDN_Rogers-Majestic_R221.gif
   

[John Greenland]

Les,

I have always found that type of connection shown on a drawing has always been a tap off of the resistive element not a wiper.

I believe that it is used for equalization purposes on the audio.

Good luck.

[Ralph Spracklin]

Hello Lee

I have seen one of those Volume Control/ Switches with what seemed to be a second wiper. But I never pulled it apart to examine how it worked internally; You could pull it apart. What do you have to lose?? It is already broken as to the switch itself! I had a similar problem with a Cdn. Westinghouse volume control/switch. I pulled it apart but could not fix the switch. So I simply disconnected the leads to the switch and hooked up a tempory On/Off toggle switch until I find another/proper Volume/On/Off switch. The problem with taking the switch assembly apart , is that you must drill out the rivets (usually two). You may get lucky and find that it is just a bent stop caused by someone using brute force. If that is the case all you may need to do is just re-straighten it. However in reassembling it you may not be able to use screws to put it back together. As I said, It is already broken! Nothing to lose!

Ralph

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