[Test-Equipment] Tektronix 2235 Wierd Problem/Question & Availability

[Dave Wood]

Robert, I had an issue similar to this with a scope plug in for a Cushman
service manual.  Turned out to be power supply ripple from some bad caps.
Try there first.  73  Dave

On Tue, May 8, 2018 at 2:40 AM, Robert Downs via Test-Equipment <
test-equipment at mailman.qth.net> wrote:

> Last summer, I bought by accident a 2235, when what I really meant to buy
> was a 2335.  Before I try to re-home the 2235, I need to mention the one
> problem it has (I didn't have a chance to do anything more than turn it on
> and confirm that it had a trace when I bought it).
>
> When I got it home and installed it above the work bench, I discovered that
> when I connected it to the audio sig gen, the horizontal channel/sweep,
> trigger, intensity, etc. all worked as expected.  However, the vertical has
> a problem that I can't offhand even think of a way to make it do.  About
> the
> left 60% and the right 20% of the display looks fine.  But between about 60
> and 80 percent across, it looks like the vertical sensitivity is modulated
> or decreased by one cycle of a rather low frequency sine wave.  Weird
> looking.  It starts off with no effect, the vertical amplitude decreases
> symmetrically to about 20% and then it goes back up to where it was.  It
> stays in sync with the triggered sweep and doesn't move if I change the
> sweep rate.
>
> Has anyone ever seen anything like this?  Everything else about the scope
> looks or works fine.  But no one would want to have to use it with it
> misbehaving like this.  I'm not really interested it fixing it and intend
> to
> offer it as a parts set but wanted to make sure that that no one can think
> of anything wrong with the CRT itself that could cause this.  The scope is
> in Houston.  If it were a 2335, I'd use it for parts to fix my original
> 2335
> (no trace).
>
> Robert Downs
>
>
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