In article et,
says...

"Dick" wrote
My Tek 465 scope has developed a minor but annoying fault in its
triggering circuitry

It sounds (reads) like a bad connection.

By Ole Occam's razor, and a description of the problem - 'it works
till I touch the knob' - my first guess is a dirty and/or worn
synch selection switch or trigger level pot. The pot wouldn't
happen to have one section for Ch. A and one for B and get
bypassed in Auto, would it?

If it were mine, I would first try a spritz of contact cleaner into
the switch via the front panel slot (IIR465C). All contact
cleaners are the same - mineral oil and alcohol - so the cheapest
Radio Shack stuff works as well as anything. WD40 also works well.

NONONONONONONO!!!! DEFINITELY NOT!!!!!

All contact cleaners ARE NOT the same! Never have been, never will
be, and the proper ones for degreasing electronic equipment do NOT
contain any mineral oil!

I speak from knowledge gained over 25+ years of pro experience in
the fields of radio, electronics, and computers. NEVER, under ANY
conditions, use WD40 inside a Tektronix 'scope or any other electronic
device! It leaves an oily residue which will actually ATTRACT dirt and
gunge, and make the problem worse.

If you value your test equipment, don't cut corners on the stuff
you use to maintain it. Check the Tektronix service manual for the
recommended cleaner formulation, and get it from a quality electronics
supply place (Radio Shack does NOT come under that category as far as
I'm concerned).

I can tell you from personal experience that CRC 'CO Contact
Cleaner' works very well, and it is plastic-safe so you won't damage the
innards of the vertical attenuator assemblies.

It may cost a little more up front, or be a little harder to find,
but you won't be risking the long-term life of said equipment.

Happy hunting.

--
Dr. Anton T. Squeegee, Director, Dutch Surrealist Plumbing Institute.
(Known to some as Bruce Lane, ARS KC7GR,
kyrrin (a/t) bluefeathertech[d=o=t]calm -- www.bluefeathertech.com
"If Salvador Dali had owned a computer, would it have been equipped
with surreal ports?"


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A number of the switches on the 465 use PC board pads as contacts. They
have heavy gold plating, but eventually the gold wears off. When that
happens, the switch is dead and as far as I know can't be repaired. You
might be able to squeeze a little more life out of it by cleaning, but
in any case I'd be very careful not to use a cleaner with any abrasive
qualities. If cleaning doesn't cure the problem, worn pads might be the
cause.

But by all means check with the 'scope newsgroup. I'm sure you'll find
folks who have had a lot of experience with the 465, and some might even
know of some kind of fix or replacement for worn switch contact pads.

Roy Lewallen, W7EL