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
> >
> > >
>
>
>
>
>
