[Hallicrafters] Re: [Hallicrafters]V4#529 - Battery Holder cleaning

[Phil Barnes-Roberts AD6PQ]

At 04:04 AM 4/14/04 -0400, hallicrafters-request at mailman.qth.net juggled 
the keys to produce...
{snip}
>Message: 1
>Date: Tue, 13 Apr 2004 09:04:02 -0700 (PDT)
>From: T Wentkie <twentkie at yahoo.com>
>To: hallicrafters at mailman.qth.net
>Subject: [Hallicrafters] Battery compartment cleaning and SX-100 "S" meters
>
>
>Does anyone have any suggestions on how to clean up a
>battery compartment on a plastic portable radio. Also
>where can one get a SX-100 "S" meter fixed as the coil
>is untangeled? Thanks. Tony
{snip}

Hi, Tony & All--

After looking all over the Web and swapping e-mail with several vendors 
(battery vendors _really_ don't want to talk about cleaning-up leakage 
damage!) the following seems to be a consensus.

Alkaline batteries and NiCads have one thing in common; the white crust 
they ooze after death is alkaline, which means a base (as opposed to an 
acid.)  So the first thing I will use on a calculator, [or portable plastic 
whatever] battery box is some vinegar.  One vendor suggests watering it 
down 50-50, from 5% acetic acid to 2.5%.  If it's awkward to put together a 
dropper bottle of 2.5%, just put a little in a cup.

The second tool is an old toothbrush.  This with some of the vinegar will 
fizz the crust on your contacts and should help keep further corrosion from 
happening once all the crust is removed.  I should add at this point that 
it is _very_ advisable, if it's at all possible, to remove the 
battery-holder from the unit.  If it just can't be done, I try to hold the 
item up so any runoff is _away_ from any other electronics.  Acid, after 
all, is yet _another_ corrosive chemical that we don't want to expose our 
circuit boards, etc. to if it's avoidable.

Once all the white crust is gone, you may have some green corrosion 
products on your contacts.  Any of this that won't go away with vinegar is 
a continuing open hazard area, since it's now below any protective plating 
that was ever there.  It will need protected.  More on that later.  Oh- and 
look carefully _behind_ all these contacts, since some crust can hide back 
there and continue the erosion of your metal.

OK, so now you've got all the crust off, including the other side of the 
plastic where wires go, and carefully inspected the rest of the unit and 
removed (in the same way) anything that's there (including on PC boards.)

The next step is a rinse with distilled water, maybe several rinses, trying 
as before to keep it out of unwanted places.  Paper speaker cones are 
especially to be protected.  A little squirt bottle is helpful here, in 
directing the stream.

Once you're satisfied the acid has been washed away, a final rinse in 
alcohol is in order.  Drugstores and supermarkets (at least here is SoCal) 
now carry 99% isopropyl alcohol, about as pure as you can get.  Again, 
don't get it on your speaker, and remember the idea is to scavenge the 
remaining drops of water here and there.

Dry it off; lay the parts, open, on a towel in front of the heater 
(obviously not too close!) or warm the oven to 150oF and turn it off, put 
it inside (with the light on as a reminder!) or with a fan blowing warm air 
across it, overnight.

Last step; I like to put a little toothpick smear of petroleum jelly as a 
protectant on any metal that's been corroded.  Ambient warmth will cause 
this to ooze a bit, and continue on into the little inaccessible places as 
an oily film.  Don't use too much, you don't want it on everything, just a 
film on damaged areas.

I've brought back several flashlights this way, and a few calculators and 
other hand-held items.  If something is eaten through, more repair will 
obviously be in order, but you should be able to arrest it if it's not been 
fatal.
===========

Rebuilding S-meters is something usually best left to the meter-movement 
surgeons already recommended.  It's possible to do it yourself, if you feel 
like being a watchmaker for the day, but be prepared for frustration and 
oopses.  And then send the carcass to the pros, with loose parts wrapped in 
another separate box.

It's a hobby; have fun!

-- 73, Philip Barnes-Roberts AD6PQ | mailto:pbarnrob at acm dot org
The difference between Death and Taxes?  Death doesn't
get worse every time the Legislature meets!