[Amps] SB-220 Submerged

[Paul Whatton]

Hi Bill

An amateur friend of mine has a business hiring out PMR radios. As you 
can imagine they sometimes come back from hire in a terrible mess having 
been dropped into everything you might imagine, the least of which is 
dirty water. His solution is to drop them into an industrial ultrasonic 
cleaning bath and then, as Gary suggested, oven bake them dry. Over the 
years he has "subjected" hundreds of radios to this treatment and, 
without fail, if it is done carefully, they work fine afterwards. The 
ultrasonic cleaning bath is filled with tap water and a splash of some 
commercial additive is added. I can find out what it is if you want.

One day he suggested I might want to clean my transceivers by dropping 
them in the bath. I was very reluctant but, what the hell, I trusted 
this old friend. I did remove the mains transformers for reasons which 
will become clear but otherwise I dropped whole rigs in the bath and 
then oven dried them. Bingo! Not only did these radios work but they 
worked better because the ultrasonic cleaner had got to all the contact 
surfaces in the plugs, relays etc. The front panels sparkle like they 
are new.

The only reason I removed the mains transformers was drying time. When 
water gets inside the windings it is difficult to dry out.

What have I learnt from this? Water itself, even tap water, isn't a 
problem provided that the radio is FULLY dried out. Dirty water, the 
kind you have experienced is a problem because the impurities make it 
conductive. Even if it is dried out you may experience problems from 
conductive deposits and/or corrosion.

What to do? In my opinion you should wash the SB-220 very thoroughy. I 
think that means taking it out into the yard and very thoroughly hosing 
it down. There is nothing to loose by doing this, it already has dirty 
water in it. If you can find someone with a big enough industrial 
ultrasonic cleaner then put the whole amp in it. Then dry it. And then 
dry it again. It will take hours and hours., days and days. By all means 
oven bake it or use the hot Sun. Total drying is vital. Last week I 
dropped a friend's 2m mast-head preamp which was badly corroded and, he 
thought, a write off, into the ultrasonic cleaner for 20 minutes. After 
3 hours oven baking there was still sufficient moisture inside the tuned 
circuits to de-tune it. After a week in the hot Sun in my shed it worked 
perfectly. Thorough drying is crucial.

Good luck! With patience I am sure you can save the amp.

Paul G4DCV

Bill Smith wrote:

Other than the obvious "dry it out" what should a guy
do to get a SB-220 back on after having been submerged
in a basement for over a week?

A friend of mine was away when a very bad storm
flooded his basement.  The water flowed up the stairs
and out the front door!!  So much for living at the
bottom of the hill and having no check valve on his
sump pump connection to the city sewer!!  Against city
rules many people had connected their sump pumps to
the city sewer.  That in turn over loaded the system
as well as the water coming down the street filled a
lot of basements.
73,
Bill

Bill Smith KO4NR


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