Re: Advice on fixing 2465B slow horiz sweep


Siggi
 

Hey Grayson,

It'd be helpful if you could describe what you've done and seen in some
detail. Detailed observations are vastly more likely to produce useful
advice than writing up your conclusions.

Inline...

Siggi

On Sat, Jul 24, 2021 at 12:57 PM Grayson Evans <wa4gvm@gmail.com> wrote:

I suspect horizontal gain drift since that fits the symptoms and I don't
know of any other problem.
Like I said, if you have the *same exact* offset at *all* sweep speeds, and
on the cursors, then this could plausibly be horizontal gain. From what I
can see, the 1X and 10X CRT gain are adjusted separately, so you can
further verify that it's the 1X gain that's out if the sweep is OK at 10X.
This is a case where you can describe what you've done and what you've
observed in order to get better advice.

The horizontal gain is adjusted first in the CAL01 procedure with R860 (1X)
and R850(10X).
Note that the sweep speeds are under software control through
control voltages from the DAC on the A5 board. These are adjusted
throughout the rest of the CAL01 procedure.


I replace all the electrolytics in the power supply and everywhere else I
could find one.

Do you have surface mount electrolytic caps on your A5 board? Had they
leaked?

Join TekScopes@groups.io to automatically receive all group messages.