[R-390] Removing 390 non-a varnish

[Dan Merz]

Hi again,   I noticed that a half-scratched away "MFP" was painted on the side
of the i.f. chassis,  so that answers part of my question - though I wonder
whether the "contains mercury" is a known fact or a rumor,  not that it's going
to matter much to me since I try to minimize inhalation of any fumes from any
unknown thing that I vaporize,  Dan.

Dan Merz wrote:

> Hi again,  looking around a bit in the archives,  I suppose this varnish is
> the MFP stuff.  Was this used on all 390 non-a's?  Evidently some types
> contain mercury with some potential hazard if overly consumed or inhaled.
> I'm not worried yet !! None on the switch solder joints so I guess they
> sprayed it before assembling the switches so the contacts wouldn't be coated
> - clever fellows that they were.  Anyway,  I gathered that this stuff is
> probably best just flaked off where heavy deposits lie if I'm going to
> solder there and make as many connections as possible without messing with
> the original coated soldered connections.  I'm open to other methods if
> there is some experience that would simplify this task,  thanks,  Dan.
>
> Dan Merz wrote:
>
> > Hi,  sure this has been discussed before - on a 390 non-a i.f. chassis,
> > there's what appears to be varnish on many of the solder joints (not
> > all,  none on selectivity switch).  I am doing considerable connection
> > modification to convert the filaments to the 390a  6 volt hookup.  Is
> > there an easy way to clean this stuff off prior to applying the iron?  I
> > have some solvents such as acetone, laquer thinner and alcohol.  This
> > stuff appears to be selectively applied to various connections and not
> > sprayed over the entire chassis though I can't be sure,  Dan.
> >
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