Re: Tek 454 Ch1 Vertical Drift


Stan or Patricia Griffiths <w7ni@...>
 

Hi Terry,

Comments inserted below:

Terry Brown wrote:

Stan, I removed and reseated all the Nuvistors I could find and also checked
transistors in the sockets to see if loose. That seems to have solved the
drifting issue. I'll let it cool down completely and retry later.
That may be all that is required to fix the drift.

Are the 454's very sensitive to movement...i.e., do the
transistors/Nuvistors and other parts move around with just normal carrying and
storing of the scopes?
No, not normally. But you have to remember all 454's are now at least 30+ years old
and things like nuvistor sockets and transistor sockets can get a little oxidized
after that much time. Sometimes all that is required to fix an intermittant socket
is to remove and reinstall a transistor or nuvistor a couple of times.

I also noticed that the leading edges of the calibrator square waves have a
slight upward/downward curve to them (even using a straight patch cord in place
of probes). Is that normal or does it indicate some need for recalibration?
You may looking a the calibrator signal in the "AC" postion of the vertical input
coupling switches. (These are the horizontal lever switches near the input BNC
connectors.) Try the "DC" position and see if it doesn't look a little better.
The calibrator will look a little slanted in the AC position.

Glad to help, Terry. Let me know if I guessed this one right . . .

Stan
w7ni@...

Thank you, again, for all your help and sharing of knowledge.
Terry

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