[Hallicrafters] Tuner Cleaner (Radio ShacK)

[Barry H]

The answer isn't that it doesn't happen because it hasn't happened to you (yet).  The answer is -- as with most things -- it depends.

Whether a switch will bind or not depends on the specific design and condition of the stationary wafers and rotors.  It also depends on which contact cleaner is used and exactly how it is applied. There has to be enough excess to reach the die-cut edges and enough to saturate the wafers.

Rotary switches vary quite a bit - different designs, and even between samples of the same switch in just how close the rotor wafer -is to the stationary one.  In many switches, there's plenty of room and no problem if any swelling were to occur.  In others, the edges are very close, nearly touching, and yet in others, there may even be some overlap.

Also probably depends on the specific composition of the phenolic, how it was die-cut, whether or not it was sealed with anything, existing wear, etc.  The flat, semi-glossy surfaces do not absorb much if anything -- fairly impervious.  It's the cut edges where the cleaner could be absorbed into the stuff.

The cleaners vary quite a bit.  One known to cause swelling is DeOxit D5 in the aerosol can.  I'm told that version contains naptha as the primary solvent and cleaning agent.  There are one or two other D5 formulations that uses something other than naptha -- a non-flammable alternative, and a different formula is marketed in Europe, etc.  D5 works initially as a cleaner -- which is what we usually need, which evaporates leaving a thin protective coating which provides lubrication and prevents further oxidation.  

D100 -- which comes in smaller applicators -- has no solvent.  It is for use on switches and connectors that are new or already clean.  You wouldn't spray that on or use very liberally as you'd run out of it before you finished the typical bandswitch and it is very expensive by volume.  I doubt if there is any risk of swelling with D100 -- it's probably the naptha solvent in the D5 aerosol.)

I had a single or double wafer switch swell up after using D5 once and I've read of a few other cases.  It could barely be turned and there was a risk of breaking the switch if you force it.  Fortunately, in my case, it was not a huge bandswitch.  It did free up after a while.  Also read the same in one or two other cases that were posted -- the cleaner/solvent will evaporate out and the phenolic will shrink back down.  So, in the rare event that it should happen, just swab up what you can and wait a few hours or a day or two -- just don't force the switch.

Blind spraying should be avoided for other reasons -- for one, you just waste the cleaner and this stuff goes for more than $10 a can these days.  Second, you should attempt to see all the wafers and rotors with a bright light and clean off any dust.  Also check for signs of arcing -- a bit of char.  That will not come off with cleaner and should be scraped off.  It may be indicative of a failing component.  The char -- carbonized phenolic -- can be conductive and cause a short.

Wherever possible, I try to apply D5 only to the metal part of the rotor and the stationary contacts.  f there is a bit of overrun of the cleaner onto the wafers, it's not generally necessary to clean that up.  However, if there is a part where it has formed a slurry with dust, etc. that could be a problem -- as someone else pointed out.  Really dirty switches should probably be cleaned with denatured alchohol or 90% isopropyl, etc. first.

Basically though, if you study the switch first and can pretty much see that there's a clear gap between the parts - not edge-to-edge or overlapping -- there is practically no risk of the swelling/sticking problem.  

There are some switches where it's impossible to see all of the parts or control the application of cleaner -- such as the bandswitch towers on tube Transoceanics.  They're all sliders and I've blasted them with no problem.

Binding switches due to use of cleaner may be a rare problem, depending on a bunch of things.  I do recommend you look before you "shoot"  -- or don't look, but ask yourself "Do I feel lucky?"

(heh heh)

Barry



















-- Bill Gerhold <k2wh at optonline.net> wrote:
I have to put my .02c in on this.  Wafer swelling was debated a while back
on this site.  Except for the poster who said wafer swelling was a problem,
all other respondents, to the man, disagreed.

After performing restoration on many receivers and transmitters with the
phenolic wafer switches, I have never had this problem even when soaking the
wafer switch.  Of course caution should be observed when cleaning these
wafer switches, but I think the wafer swelling may not be entirely accurate.
I am not saying it cannot or never happened, but I think the incidents of it
happening may be very scarce.

K2WH

-----Original Message-----
From: hallicrafters-bounces at mailman.qth.net
[mailto:hallicrafters-bounces at mailman.qth.net] On Behalf Of Clayton L.
Nicolsen
Sent: Sunday, November 20, 2005 9:10 AM
To: Hallicrafters at mailman.qth.net
Subject: re:[Hallicrafters] Tuner Cleaner (Radio ShacK)

One other important point about using spray tuner cleaners...

As you already mentioned, spraying it liberally on wafer switches, 
especially old ones, can be a problem as it can frequently cause the wafers 
to swell and the switch won't work properly.  As a previous thread stated, 
use some alcohol to remove some of the solution from the wafer.

However, a bigger issue is the tuning capacitors.  Never, never spray any 
kind of contact cleaner that leaves a residue on tuning capacitor fins.  
This will change the dielectric constant of the capacitor and dramatically 
change the alignment of the radio.  You also will need to clean the tuner 
residue from the capacitor fins.  The alcohol will work, or you can use any 
commercial spray cleaner.  Keep it out of the shaft bearings.


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