I'm not sure exactly what the "57" represents, but I
think at least part of it specifies the phosphor --
which, I believe, is a longer persistence type. Note
the blue color.
David
--- In TekScopes@...,
Cliff White wrote:
>
> Question: Why does his scope say "Type 532-57"?
My 532 just says "Type
> 532"... ?
>
>
> On 04/10/2013 03:30 PM, Steve wrote:
> >
> > --- In TekScopes@...
,
> > David Sligar wrote:
> > >
> > > Hello, Group --
> > >
> > > As possibly many new members do, my
first post is a plea for help.
> > Once my very nice 532 is working again, I
might decide that I prefer
> > "reliable" to "elegant" -- and trade this
one in for something a
> > little newer.
> > >
> > >
> > > I've been using this scope on a daily
basis for about a month. On
> > Friday morning I tuned it on and suddenly --
no sweep. I've been
> > going through the beast as carefully
> > > as I can, looking for the bug.
> > > Tubes all check good, no visible damage
/ exceptions, "all" voltages
> > measure
> > > correctly. I suspect one might need a
(working) scope to figure out
> > > where the sweep waveform disappears. I
decided I'd try running my
> > > function generator as external sweep --
it worked, so that says at
> > least
> > > the horiz. amp is OK. I've now spent a
couple of days
> > > and I'm not sure I'll be able to find
what's wrong.
> > >
> > > Amazing how helpless we are without
tools! I hope one or more of you
> > will be able to suggest where I should look.
> > >
> > > Thanks very much,
> > > David Sligar
> > > Grants Pass, OR
> >
> > David,
> >
> > A second scope would be very helpful, but
you may be able to do some
> > things without it. Selecting a very slow
sweep speed (1 div/sec) would
> > allow you so see the sawtooth on a DMM.
> >
> > First you need to isolate the main area not
working. It could be at
> > least three -- trigger, timebase, or
blanking. Turning the Trigger
> > Stability control to the far right should
force the scope to free run.
> > This does not isolate the trigger circuit
however. It only biases the
> > multivibrator in a way to have it reset when
the sweep length
> > comparator trips at the end of the sweep.
> >
> > With another scope, you can trace all of the
trigger circuit fairly
> > easily. I usually use line trigger mode when
doing this, as I know
> > this gives a reliable signal, eliminating
the possibility of a problem
> > in the trigger pickoff circuit in the
plug-in. Trace the signal
> > through the comparator(V308), and verify the
Trigger level control
> > moves the grid voltage around (pin 9 for all
+ polarity settings, pin
> > 2 for all -- mode positions).
> >
> > I was hoping to disable the unblanking pulse
to rule that out, but I
> > don't see a way to do that simply by pulling
tube, as the signal is
> > generated in a dual triode (V430B) that is
shared with the trigger
> > multivibrator. Unfortunately, the AC
coupling to differentiate the
> > pulse occurs before these tube stages, so
there is no place you can
> > easily short to ground or a supply to get a
stable DC bias voltage.
> >
> > If the trigger is going through OK, then you
need to focus on the time
> > base. Use the circuit description in the
manual to guide your
> > troubleshooting.
> >
> > Let us know your progress. Your scope looks
really clean and is worth
> > preserving.
> >
> > - Steve
> >
> > >
> >
> >
>
