Potentiometers TR20...
 
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Potentiometers TR20xx

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Pawel
(@pawel)
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Joined: 3 years ago
Posts: 116
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Hello

There are several types of potentiometers used in the TR20xx products. Below you may find information about the most common types with my comments. In general I may say that:

- I couldn't find any direct replacement;

- they are at least 42 years old, but still works quite good;

- majority of them you may open and clean;

- all of them having two separate potentiomenters inside;

- when you use the potentiometer cleaner ( spry ) use just a 'drop' not 5sec spry;

- you have to desolder it if you want to open and clean. If you want just spry it you may do it without desoldering;

Type 1, the most common for Balance/Bass/Treble at TR2025/30/40/45/60

It's easy to clean, you may open it and clean. One track can be de-assembled, the second one will stay in the chassis, but with good access for cleaning. If you want just spry there is a eyelet at the back and left side of the chassis and you may use it.

Type 2, the most common for Balance/Bass/Treble at TR2055/75/80

 

 The same comments as above, just the eyelet is on the top.

 

Pawel


   
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Pawel
(@pawel)
Member Moderator
Joined: 3 years ago
Posts: 116
Topic starter  

Type 3, the common for Volume at  TR2025/30/40/45/55/60

Well, I don't like this one. If you don't have special tools, do not even try to open it :). What you may do and it helps: just desolder it, use the IPA spry to clean it ( big hole at the top ), use the  compressed air and dry it, and then one drop of the potentiometer cleaner to each track. It usually helps. This one has the very delicate rings with the graphite pin and it maybe broken ...I didn't find the way how to repair it. If you have to open it contact me I will try to help. The one on the picture had been opened.

Type 4, the common for Volume at TR2075/80   

 

so far so good, I have not been forced to open it, one drop of the potentiometer cleaner solved all issues.

There are a few more types, but they are not very common and very similar to described above. One more generic comment reg Volume. As it is build based on two separate tracks and usually has 40 years + it may happen that the left or right channel starts a little bit earlier with the volume. It is how it is, no way to fix it is probably due to the micro-clearance on the plastic parts.  

Pawel


   
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Tandbergista
(@tandbergista)
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Joined: 3 years ago
Posts: 84
 

@pawel What a super informative post, thanks!

I have been looking for replacement pots, and ways to make them fit.
The biggest problem is the volume pot though because it has a center tap. There are NOS pots that can be adapted. I bought a bunch from The Tube Room in Canada.
For balance, treble and bass you can find replacement in Mouser and such places. I just bought a bunch from TME in Poland and managed to successfully replace a treble pot in a TR-200.

It seems there are Alps pots with center tap that are still being made in Japan. These should with some modifications be possible to fit in to replace a volume pot. I haven't been able to source these pots though. I hope to go to Japan maybe next year and I will try to find these pots there.


   
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koba
 koba
(@koba)
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Joined: 3 years ago
Posts: 55
 
Posted by: @tandbergista

It seems there are Alps pots with center tap that are still being made in Japan. These should with some modifications be possible to fit in to replace a volume pot. I haven't been able to source these pots though. I hope to go to Japan maybe next year and I will try to find these pots there.

Have bought these direct from Alps 3 or 4 years ago

https://tech.alpsalpine.com/prod/e/html/potentiometer/rotarypotentiometers/rk16/rk16_list.html


   
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Tandbergista
(@tandbergista)
Member Admin
Joined: 3 years ago
Posts: 84
 

@koba
These are for tone controls, no center tap for Loudness?

By the way, I have an interesting idea for how to adapt the original axles to new potentiometers. Have experimented with this. Now found these RC model motor axle adapters on ebay, they have them in different sizes. If you buy a 4mm-6mm adapter, it will probably fit the new pot axle and the old original Tandberg axle (which is just under 4 mm).

If you want to make a new axle for the knob (rather than saw off the old one), you can buy the 6mm-6mm adapter and make a new axle from 6 mm metal rods.

I have not tried this, but I am buying a bunch to test.

 


   
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koba
 koba
(@koba)
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Joined: 3 years ago
Posts: 55
 

@tandbergista

You can check specs by pressing the name of the product in the list below by the link


   
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