The volume control is specified in the service manual as 200k linear. That is possibly an error but either way, you won't be able to buy a centre-tapped pot unless you luck upon a copied or NOS ALPS RK27 or perhaps a similar vintage type.
A standard 220k value will also be fine, bearing in mind that most pots are now terminated for PCB insertion - not wire-wrap. However, the shaft size of modern pots will only be 6mm and the mounting bush will be be smaller too. Unfortunately, you can't rely on stocks of obsolete components. They come and they go quickly.
I suggest trying a standard, 27mm dual 220k log. pot and simply ignore the loudness tap connection. It's cheap, simple and if it works satisfactorily without the loudness feature, is an easy fix. Personally, I dislike loudness controls but if you want the receiver in original condition, good luck with the search.
A standard 220k value will also be fine, bearing in mind that most pots are now terminated for PCB insertion - not wire-wrap. However, the shaft size of modern pots will only be 6mm and the mounting bush will be be smaller too. Unfortunately, you can't rely on stocks of obsolete components. They come and they go quickly.
I suggest trying a standard, 27mm dual 220k log. pot and simply ignore the loudness tap connection. It's cheap, simple and if it works satisfactorily without the loudness feature, is an easy fix. Personally, I dislike loudness controls but if you want the receiver in original condition, good luck with the search.
Try cleaning the carbon track and wipers first with Electrolube Switch Cleaner/lubricant. You will be pleasantly surprised.
I use EML200F | Electrolube EML 200 ml Contact Cleaner Aerosol | RS Components
I use EML200F | Electrolube EML 200 ml Contact Cleaner Aerosol | RS Components
)? Does your unit possibly feature a muting clamp or something like that?
Basically, nobody replaces this sort of pot unless they absolutely have to. Tapped volume pots tend to be custom orders, replacements not generally being available beyond the original manufacturer... and you can probably guess what that means for a device from the 1970s.
Cleaning pots is a bit of a science in itself, you need to be very picky with what you use (it should not degrade phenolic board for one thing). That said, with the right stuff they usually come back nicely. More severe cases may appreciate flushing with cleaner first and using sealant later.
Cleaning pots is a bit of a science in itself, you need to be very picky with what you use (it should not degrade phenolic board for one thing). That said, with the right stuff they usually come back nicely. More severe cases may appreciate flushing with cleaner first and using sealant later.
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