Re: 2445 “A” sweep Issue


Siggi
 

Hey Christopher(?),

inline.

Siggi

On Tue, Sep 8, 2020 at 9:59 PM <christopherbath@hotmail.com> wrote:

I am having issues with a 2445 Oscilloscope that is not showing the A
horizontal sweep.

This is a base 2445 as opposed to 2445A or 2445B?


The “B” sweep appears when the B delayed time base is used. The readout
shows some dots on the bottom line of text on the CRT. And the A sweep
appears to have a starting dot which is offset to the left of the CRT.
You may need to post a picture of what you're seeing on the CRT, and don't
forget to show the front panel control settings. You'll need to create a
new album in photos (https://groups.io/g/TekScopes/photos) and please link
the new album from your post.



I had wondered if the 2445 has issues with the horizontal output hybrid
(as the “A” sweep is offset to the left) or the Z-axis hybrid (as there are
dots on the CRT).

Depending on how this is manifesting, it could be that the dots are
signifying that the scope has lost calibration. Does it go through power up
self-tests at power-up, or do you need to press a button before you get to
sweeps?


As the “B” sweep and readout appears however this seems to imply that the
horizontal output hybrid may be working?

If you get a readouts and/or a sweep, that'd indicate your
horizontal/vertical output hybrids are working.


I am not sure is there could be a failure mode of the horizontal output
hybrid which results in the “A” sweep not appearing.
You've verified that triggering works? More likely than an output hybrid
would be a trigger or some kind of a control problem.


I have swapped the “A” and “B” sweep hybrids which did not resolve the
issue.

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