[R-390] R-390 alignment attempt #1, need advice

[Tisha Hayes]

That long, multi section rotary switch beneath the RF deck can be a real
challenge to work on. Be very careful not to bend of break any of the
contacts if you attempt to clean it.

Remember that those are silver coated so it is not unusual for them to look
black. That is silver oxide and it is still conductive. Unless you know
that it is a wiper contact issue with a certain wafer I would at the most,
spray it down with de-ox-it and leave it alone. Accidentally hooking one of
those contacts will take the spring out of the connection and then it will
be really intermittent or open.

The trimmer caps near the crystal deck are problematic. I usually make a
little cheat sheet of trimmer positions, then turn the deck over and give a
concentrated shot of something like de-ox-it (cleaner) with the nozzle tube
right into the trimmer. Then while it is still wet I will spin that trimmer
capacitor around a bunch of times, and give the trimmer another shot of
de-ox-it and set it back to the position it was originally in.

Of course you are going to need to do a complete realignment of the
oscillators and you not only want trimmers that get you on frequency but
ones that do it without being all jittery and intermittent. Oftentimes it
is dirt or contaminants in the trimmer that makes it behave spooky.

The same holds true for crystal sockets and pins, clean them off and
re-seat them snugly.

I have never tried to disassemble the trimmer capacitor itself. I have
enough hangar-queen modules that I will cannibalize for spare parts.

-- 
Ms. Tisha Hayes. AA4HA

*""In this denial of the right to participate in government, not merely the
degradation of woman and the perpetuation of a great injustice happens, but
the maiming and repudiation of one-half of the moral and intellectual power
of the government of the world." -- Fredrick Douglass"*