Jim Yanik wrote in
:

"Jim Lacko" wrote in
:

I have an old Tektronix 3347A 100 mHz scope with an control problem.
Power-up is OK and runs fine for about 5 minutes then all buttons become
inoperative (all lighted buttons go dark) but CRT display is fine.

Anyone know of a website with ideas for this scope?

Thanks!




I never heard of a TEK "3347A" o'scope,old or new.

I suspect you mean "2247A".

First you need a 2247A SERVICE manual.
(At least those still had schematics in them!)

The top PCB is the microprocessor/digital board.
You may have a thermal problem with some IC on the uP board.


It's also possible that the PS filter caps for the 5 volt supplies have
degraded and ESR risen.Of course the first circuit checks should always be
the power supplies;DC voltage,ripple,and regulation.

--
Jim Yanik
jyanik
at
kua.net