"Ed G." wrote:

I have put an old Allen wrench into a stuck slug and heated it
with a
large soldering iron, then carefully remove the slug by turning the
Allen wrench with a pair of pliers while the slug was warm enough to
melt the wax.


That's a good way of transferring the heat. But care must be taken
not to tork the allen wrench too much. I've broken far too many slugs
with those inflexible steel tools.

One other thing, some coils are sealed with "Printer's Ink", a
water
based ink that chips easily. We used it on all the coils in the
PRC-77 radios built by CE.

Thanks for that reminder. Forgot about some water soluble sealers.


You have to be careful drilling holes in circuit boards. I have
worked on a lot of RF boards with traces run under coils that will be
destroyed with a drill bit.

That's a given, that care must be taken where you drill. I've never
damaged a trace yet, though I've opted not to drill some. Of course if
the board has internal traces (sandwich) forget it!!

Ed

The last boards I worked on were 16 layer. About the only place you
could drill was through a bad via the connected the top and bottom
layers. At up to $8000 per board, they were rather fussy about extra
holes in new boards.
--


Michael A. Terrell
Central Florida