Re: tek 475 vertical position pots

Emanuele Girlando

An update.
I spent two hours in dismounting the vboard and un removing the pots
from it. What a nightmare! If any other people is about to start an
adventure like this, please be sure to have a perfect and efficient
unsoldering machine. I spent a lot of time trying to get rid of the
tin that was keeping the pots on the board. My solder sucking tool
was insufficient. I used a thin plaited wire to get the tin out of
the PCB holes by capillarity.
The pots are now in my hands and I am going to work on them the next
weekend (hopefully).
until next time

--- In TekScopes@y..., "Emanuele Girlando" <emanuele_girlando@y...>
I confirm: "the pots are Allen Bradly, and have a double section";
one section seems unused (not connected).
I confirm: they are "the ones which you can nicely open with four
So your tips are very very useful.
For the sake of completeness and want to say that I have already
tryed to turn them back and forth a lot of times but with almost no
Furtheremore it is impossible to squirt any form of conctact
without opening them.
Thank you very much for your contribution, I'll keep the list
on my activity.

--- In TekScopes@y..., pe1fbo@h... wrote:
--- In TekScopes@y..., Emanuele Girlando <emanuele_girlando@y...>
Vertical position pots on my tek475 are so noisy to make my
almost unusable.
Any suggestion on refurbishing those pots?
They are two sections pots, can I try to use the unused section?
Any source for them?
Thank a lot !


Emanuele Girlando (IW1DHI)

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Hi Emanuele,

Those pots are probable Allen Bradly, and and have a double
There are two type of AB pots, The plastic sealed ones, and the
which you can nicely open with four screws. To clean the pot, you
have to take it apart (first remove them carefully from the
amp board). Once you have opened them you need to cut the plastic
seal inside the black plasic section to get to the brown whiper

If you have everything apart, remove all the old grease and clean
sections with alcohol. Mind you that the whiper has a tiny carbon
pallet, which comes loose very easy.

Once this is done you need to re-apply new grease. I use for this
purpose lithium based grease from Dow Corning, Molycote DX. Other
types of grease I cannot recomend to use. This is probably the
stuff that Bourns uses.

After this, everything has to be assembled again.

There is one small remark on this whole procedure, that is, if
carbon conductive film is worn out, the result will probably
disapoint you.

I have personally used this procedure on a lot of AB pots. They
the ones usuly having problems due to the aging of the grease.
can be restored most of the time with a good result.

- Fred de Vries

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