[R-390] ReCapping R-390A

[Kavanagh, George]

All:
Well there _are_ a few newbees out here (me for one), and I'm _very_
grateful to those list members who have gone before and for their
willingness to document and share their vast amount of R-390A knowledge and
lore.

I obtained a Collins R-390A last month (Serial#3319 of Order#8719-P-55).  It
was "known good" by its previous owner, so I fired it up and delighted in
its features and operation for several weeks).  I've obtained the
documentation (Y2K, Rev2, etc.) to which list members directed me, and have
begun to digest it.  Having discovered the potential of a lurking timebomb
in C-553, I resolved to open up the box & see if it had ever been recapped.
After purchasing a set of Bristol Spline L-wrenches (from McMaster-Carr) I
removed the IF subchassis and discovered that no recapping had been done.  I
think.  There are several "VitaminQ" caps in the IF  ( C531, 533, 536, 547,
548, 549) but C-553 is _not_ a "VitaminQ", it is marked "ASTRON" "TQFP 4982"
".01 mF 300 WVDC".

** I'm sure that this C-553 should be replaced by an OD, as recommended, but
am curious: was this ASTRON cap factory installed? 

Also, the shaft coupler on the Bandwidth shaft was a real bear to loosen; I
was afraid I would strip out my nice new spline wrench!  In the end, a drop
of LiquidWrench on the coupler's nut, and a touch of heat from a soldering
iron on the nut did the trick.  I don't think this thing has been opened up
in 50 years!

** All the tube shields are silver colored.  I have read that Collins
started using black IERC shields at some point in production - when was
that?

Recent posts to the list suggest replacing all brown color-banded caps - the
IF has 11 of these, several in quite inconvenient locations that would
require significant disassembly to do properly.

** Just how big a project _is_ completely recapping an R-390A?

Thanks for any & all comments and suggestions

George Kavanagh; KB1HFT