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!

"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.

--
Jim Yanik
jyanik
at
kua.net

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

Jim Lacko wrote:
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!




While I'm not familiar with that series, by the description of the
problem I'd start my search at the power supply.

In article 9%rCf.1150$Ix.89@trnddc07, (known to
some as James Sweet) scribed...

Jim Lacko wrote:
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!




While I'm not familiar with that series, by the description of the
problem I'd start my search at the power supply.

That's good advice. The second thing I'd do is pull and re-seat
every single socketed IC. You'd be amazed how many problems result from
simple pin oxidation.

Keep the peace(es).


--
Dr. Anton T. Squeegee, Director, Dutch Surrealist Plumbing Institute
(Known to some as Bruce Lane, KC7GR)
http://www.bluefeathertech.com -- kyrrin a/t bluefeathertech d-o=t calm
"Salvadore Dali's computer has surreal ports..."