Re: Stuck switches on 453


n4buq
 

If those are Clarostat pots, I have had good success just disassembling, cleaning, and reassembling those.

Thanks,
Barry - N4BUQ

----- Original Message -----
From: "Gary Robert Bosworth" <@grbosworth>
To: TekScopes@groups.io
Sent: Friday, July 31, 2020 1:58:55 PM
Subject: Re: [TekScopes] Stuck switches on 453

Be extremely careful when drilling into potentiometers. You will almost
always drill into the resistive wire or element and ruin the pot. I cannot
stress this enough. Gary

On Fri, Jul 31, 2020, 07:21 Abc Xyz <yawrdanza@...> wrote:

Richard,

I know a guy who told me he immerses Stuck Potentiometers/Switches in
Solution to free them up. I personally have not Witnessed the
Procedure...so take it for what its worth.
Also, I have Read where one Drills a Very Small Hole in the Body of the
Mechanism and Dribbles Solution in...again, I have never tried it or seen
it done.
I have tried turning the Scope where the Potentiometer Shaft is Vertical
and place a Few Drops of Deoxit on the Shaft itself thinking Gravity would
pull the Cleaner down into the Part...didn't work for me but it may be one
of those things where a Great Deal More Patience is Needed!

JR

On Thu, Jul 30, 2020, 10:46 PM Richard P via groups.io <wb5nen=
yahoo.com@groups.io> wrote:

I’ve used my Model 453 for years for basic audio but it has always had a
problem. The rotary switches on each of the variable sweep rate
potentiometers (one on the front panel, and one on the side) are frozen
in
the uncalibrated positions. Therefore, the “Uncal A or B” light is
forever
lit, and the sweep rate for either A or B is uncalibrated. These combined
switch/potentiometers are like a rotary volume control with an on/off
switch. But stuck. I’ve tried to loosen them up with DeOxit, contact
cleaner, even liquid wrench. But these guys are pretty-well sealed up,
and
access to them in the 453 chassis is very challenging. I can see the
shafts
moving a bit, so I believe the problem is inside the switch/pot
assemblies,
not that shafts are stuck in bushings. Any thoughts on this one?

Richard







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