[R-390] Cleaning sub-chassis

[Bob Camp]

Hi

There are three items on a 390A that probably are not a good idea to 
drown in water. The crystal enclosure, the PTO, and the plug in crystal 
oven. All have insulating material in them and will be a bear to dry 
out.

Opinions differ on the value of water dunk cleaning the rest of the 
radio. Personally I would advise against it. The metal chassis parts 
and disassembled gears are fine to scrub and wash all you want. The 
modules full of electronics are not going to take a soak in water very 
well. You will not kill the radio this way - they have sat out in the 
rain and survived. It just doesn't improve them any.

Most of the dunk cleaning was done back in the days of big open tanks 
of solvents. The EPA frowns on almost all of the things that we once 
used for this kind of stuff. If you are a part of the world where Freon 
or Tri-chlor is still legal then dunking might be a reasonable 
approach. I still would not dunk the stuff with insulation in it 
though.

WD-40 or alcohol on Q tips seems to be the most common way to clean the 
modules. With the WD-40 you can get residue and the alcohol often 
contains water. In both cases less is better. Blowing the whole 
assembly off with compressed air is a nice touch once you are done. It 
will get trapped solvent out from under stuff and you have to get 
pretty wild before you will blow parts out of an R390 with an air hose 
...

	Take Care!

		Bob Camp
		KB8TQ




On Jan 10, 2005, at 4:16 PM, richard may wrote:

> Wonder if anybody can give me some tips on cleaning an R-390A 
> sub-chassis. I want to clean a crystal osc module. I think if I remove 
> the oven cover, the T-207 cover and remove the crystals, I can give 
> this thing a bath. I remember reading somewhere how this is done but 
> can't find the article. The inside is pristine but the outside is 
> really dirty.  Any tips? Richard, W8FCW
>
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