[TenTec] Omni VI Rubbery crud on PCB

[Ken Brown]

I recommend all who own Omni VI inspect their rigs to see whether they have
this stuff on them.

If they do remove each board that has it and use tiny tweezers and
dentist's picks to remove it. Wash with isopropal alcohol.

You can see it on the TX audio/BFO board just by opening the top of the
Omni VI. To check the XTAL osc board requires a lot more dissassembly,
since it is in the enclosure under the low level driver and FM boards.

It is a lot of work, and will require realignment of the BFOs at least, but
it could make the difference between your radio failing due to the
corrosion this stuff causes over the long term or not.

DE N6KB

On Tue, Jul 18, 2017 at 2:18 AM, Gary F <dukeshifi at comcast.net> wrote:

> That stuff IS conformal coating!
>
> It it put there to reduce microphonics in VCO's.
>
> Paraffin wax would have worked as well and would not have been acidic.
> EE's are not chemists...
>
> Gary
>
>
>
> Sent from my iPad
>
> > On Jul 17, 2017, at 9:22 PM, Bwana Bob <wb2vuf at verizon.net> wrote:
> >
> > Yuk!  I've seen brown crud on the foil side of the circuit boards  my
> Paragon and another one that I worked on. In those cases the crud was
> excess soldering flux. I cleaned it off with isopropyl alcohol and cotton
> swabs.  The white stuff may be some kind of oxidation or corrosion.  Mold
> would be black.
> >
> > 73,
> >
> > Bob WB2VUF
> >
> >
> >> On 7/15/2017 7:32 PM, Ken Brown wrote:
> >> My Omni VI had some dark brown rubbery stuff on the XTAL osc and BFO
> >> printed circuit boards, It is sort of like rubber cement and reminds me
> of
> >> similar stuff I found in Kenwood TS-440s. There is also blue green
> copper
> >> corrosion on the edges of the rubbery crud along with with white powdery
> >> stuff. I think the powdery stuff may be mold or fungus. I have spent
> >> several hours on each board trying to remove it as best I can.
> >>
> >> It is not on every board, and not on any of the boards in an older Omni
> VI.
> >> I am wondering if it is something that was put there by the Ten-Tec
> >> factory, or if some previous owner did it? I guess it's purpose may be
> to
> >> dampen possible microphonics in the oscillators. It definitely caused
> some
> >> undesirable, unintended consequences in a humid climate.
> >>
> >> Has anyone else seen this in an Omni VI?
> >>
> >> DE Ken N6KB
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> >>
> >
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