[R-390] RF Deck, Module Washing (dishwasher)

Thu Mar 24 17:24:54 EDT 2011

Hi, 
I guess that there is a simple solution and we can keep using the dishwasher
idea.
It had to be with the PH of the dishwasher cleaner, it is Alkaline and the
remanent of it make surface dark after a while if there is not a good
rinsing and neutralization with a lot of water.
Tray to put the aluminum in a solution with acetic acid, Vinegar (the one
you use for you salad) and water, this will neutralize the alkaline
detergents remanent on the surface of the chassis and parts.

I work in a factory were we chrome plate brass, and if we did not neutralize
after the cleaning were we use strong cleaners (detergents and caustic soda
(alkaline), the parts will get dark or brown in minutes this is normal, this
did not happens if parts are neutralize after the cleaning with a 5% h2so4
solution and then it is important to rinse all with neutral water ( water of
the tap).
Instead SO4H2 solution I suggest to use water with Vinegar of your salad
dressing ( acetic acid ). Rinse all with water after that and later maybe
you can put in a previous warm oven, at a low temperature or dry it with hot
air from a hairdryer machine (so low temperature as possible,thinking in
caps.
All metals will oxidize after cleaning them, with the acid solution you are
neutralizing and taking out the small surface oxide that also stop the
oxidation specially in a aluminum. The small oxidation of the surface
protect the aluminum and stop the oxidation (this is not true en steel
because the oxide of ferrous parts is like a sponge ( esponja) that absorve
water and the corrosion keep going).

Maybe it will work. I did it, but not in a dishwasher.
I will try to do it with one of my audio 390A module that I have for
discard.

It is possible to start trying this with a old aluminum chassis before doing
it with any module of the r390a.

There are products to pasivate metals, in case of brass is a solution of
water and chrome, what I don't suggest to use because chrome solution should
be carefully treated after discarding them. I don't think Aluminium need to
be passivated it will create a small amount of oxidation over it after the
acetic acid and cleaning and rinsing with water.

I will ask our engineer in the galvanic and came back on this topic if still
is a issue.Until Monday we have holiday here in Argentina. That's why I can
not ask him earlier. 

Regards,
Francisco
LU3eec

-----Mensaje original-----
De: r-390-bounces at mailman.qth.net [mailto:r-390-bounces at mailman.qth.net] En
nombre de Barry
Enviado el: Thursday, March 24, 2011 4:28 PM
Para: r-390 at mailman.qth.net; Tisha Hayes
Asunto: Re: [R-390] RF Deck, Module Washing (dishwasher)

I try never to run aluminum-handled untensils in the dishwasher for that
reason.  I don't know if the recent change to dishwashing detergents have
stopped this, but it really made a mess out of one of my knives.

Barry - N4BUQ

 On Thu 24/03/11  1:33 PM , Tisha Hayes tisha.hayes at gmail.com sent:
> While reviewing the latest draft of the R-390A inspection process I found
> afew references to cleaning the RF deck in a dishwasher (Page 9, Section
> 4,activities 8,9). This brings up an interesting point for discussion and
> Iwanted to share with the reflector on my experience with cleaning a radio
> inthe dishwasher.
> 
> I have a bunch of ARC-5 stuff, one item that joined my collection was one
> ofthe ARC-5 transmitters that was in pretty rough condition as far as
> beingloaded up with dirt. Worried about things like Haunta-Virus (from
> rodentdroppings) or the many other things that can go wrong I decided to
give
> thisthing it's own cycle in the dishwasher. I pulled the tubes and the
> crystalreference plug-in and set it all by itself in the dishwasher. Since
it IS
> adishwasher you cannot use detergents that foam up so I dropped a Dawn
> dishwashing packet into the machine and let it run through a cycle.
> 
> This was set to the most aggressive cleaning cycle on the dishwasher
> (heavy)with heat drying at the end. What came out looked really nice, the
> aluminumwas even shiny. I had pulled off the bottom plate so the soap and
water
> could get up inside, below the tube sockets and removed the tube
> removalplate on top and left open the front IF coil adjustment window and
the
> little flip-door at the back top of the radio. The antenna tuner worked
> really nice and it even cleaned up most of the tarnish on the contact
> wheeland the turns.
> 
> Not thinking much more about it, and wanting the thing to sit for quite
> awhile before I applied B+ to wiring that still had some moisture in the
> cloth I left it to sit on top of a heating register in my office for a
> fewweeks.
> 
> When I got back to it the aluminum had taken on a terrible, tarnished
> look(greyish-black in appearance). It seems that the aluminum did not like
> thedishwashing method. Strange since my kitchen cookware is also aluminum
> andit does not seem to mind.
> 
> The point I am trying to make is that a dishwasher is probably not the
> bestway to wash radio modules or the RF deck. Any kind of detergent that
is
> rated to run in a dishwasher (non foaming) is fairly aggressive. I do
> notthink you can run Simple Green in a dishwasher, at least not MY
> dishwasher.
> Can other folks elaborate upon their attempts to clean modules in a
> dishwasher? (if you have tried it) What were your experiences?
> 
> It is one thing to mess up an ARC-5 (that I have almost a dozen of),
> something completely different to put an RF deck or R-390/A module in
> there.
> Maybe it is best to stick with the Simple Green, parts brush, garden
> hose,followed with distilled water routine. If the dishwasher is a bad
idea
> wemay want to remove references to that technique from the R390A
> InspectionProcess guide.
> -- 
> Ms. Tisha Hayes/ AA4HA
> -
> Optimist: *The glass is half full.*
> Pessimist: *The glass is half empty.*
> Engineer: *The glass is not sized correctly AND we need a backup
> system.*______________________________________________________________
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