----- Original Message -----
From: "john" <[email protected]>
To: <[email protected]>
Sent: Tuesday, February 22, 2011 5:24 PM
Subject: Re: [Drakelist] Dishwasher
Just a quick comment on this perennial topic.
If you clean a Drake in the dishwasher or the sink, you
may get a nice clean old radio.
_or_
You might ruin a nice old radio... but at least it
wouldn't take you long!
On the other hand, if you clean it by hand, you'll take
longer, but you'll not likely destroy a nice old radio.
As a part of this careful cleaning, you'll probably learn
more about how your radio is laid out, notice the cracked
insulator here and there, the loose wire someone forgot to
reconnect, the scorched resistor that bears investigation
and the suspect looking electrolytic, the missing hardware
here and there and perhaps a loose ground connection here
and there.
Of course it won't be fast.... (which is often a very
good thing).
John K5MO
I tend to agree with John, my worry about using a
dishwasher is the heat; both the hot water temperature and
the drying cycle although I suppose one can eliminate that.
Dishwashers are supposed to leave the dishes germ-free which
requires rather high temperatures.
I think there is a middle ground, namely the method
I've described here before using a spray gun with hand type
dishwashing detergent and warm water followed by a warm
water rinse and blowing out retained moisture with
compressed air. This is followed by baking in a low
temperature oven (about 130F) for a day or two.
There are a lot of things can be damaged by exposure to
either water or heat. Obviously, meters and loudspeakers
should be removed but there are also hidden things like
coils on paper formers. At Hewlett-Packard we also removed
hermetically sealed transformers and chokes. Why; because we
found that they often had very small leaks which would allow
some moisture to enter but then trap it causing arc-overs
even after extended baking out.
Probably plastic dials or glass dials with stencilling
on them should be removed. I could probably think of some
other stuff. Anything that can dissolve, melt, trap moisture
must be removed. This sounds discouraging but the results
may be worth it.
Liquid dishwashing detergent is quite mild but
surprizingly effective. I think the powder stuff made for
machine washing is rather more alkaline. Probably makes no
difference in a lot of places but should be tested.
Getting oxidation off usually requires the use of a
reducing agent and often abrasives, again, effective by
should be used with testing and cautions. The two most
common reducing agents are oxalic acid and phosphoric acid,
both are found in commercail rust-removers and tile
cleaners. Naval Jelly (the original kind) employes
phosphoric acid as do a number of tub and tile cleaners.
Barkeeper's Friend and Zud (and undoubetly others) use
oxalic acid. The two are not quite the same in action and
sometimes one will work better than the other. Both are
capable of removing thin chrome or nickel plate completely.
I am not sure what is in Brasso, I think phosphoric acid
along with a solvent and jeweler's rouge. I find it too
strong for many purposes plus it leaves a residue behind
that is sometimes hard to remove. I've also observed that
the residue seems to promote oxidation over time.
There are lots of polishes but plain toothpaste is a
surprizingly effective one and quite mild. It is slightly
abrasive but obviously not enough so to damage teeth.
Toothpaste will work on all sorts of plastics incuding
Bakelite. I've found it about as effective as the special
"magic" plastic polishes. Also works fine on chrome and
nickel.
Sometimes the use of steel wool is unavoidable. Brillo
has a detergent and fine jeweler's rouge in it but there are
much finer grades of plain steel wool available often in the
paint department of a hardware store. Also, try a plastic
scrubber like Scotch-Brite since they are softer and less
likely to take off too much metal or leave scratches.
Scouring powder is much milder than Brillo and will often
remove stubborn oxidation.
Sometimes one encounters surfaces coated with lacquer
of some sort. Most of this, with the exception of MFP
lacquer, will come off with either a 2% to 10% solution of
washing soda (sodium carbonate) or methyl alcohol or mineral
spirits, there are two types of varnish so you must test to
see which kind you have. I have never found anything which
is strongly effective on MFP lacquer, paint remover seems to
be best but is slow.
I quote an old friend who was CE of Westinghouse
Broadcasting here. He used to stress keeping things clean to
begin with (beyond our control with old equipment) pointing
out that more equipment is damaged by cleaning it than in
any other way.
--
Richard Knoppow
Los Angeles
WB6KBL
[email protected]
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