TEK 532 --


David Sligar
 

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



ditter2
 

--- In TekScopes@yahoogroups.com, David Sligar <d.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




Cliff White <w5cnw@...>
 

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

>



Don Black <donald_black@...>
 

It's always good to remember the basics. If you don't have a second scope, measuring the circuit DC voltages will often point to the problem area.

Don Black.

On 11-Apr-13 6:30 AM, 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

>



David Sligar
 

Thank you, Steve.
Just one comment, I have a dual trace plugin (53/54 K) as well as the
53/54 C. Neither of these gives a sweep, so I maybe can eliminate the pickoff circuits. (?)
Otherwise, I'll try what you suggest. I do think it's too soon to see this one ascend (descend?) to scope heaven.

I feel a bit over my head with this, but I'm not ready to give up. I'll let you (and the group) know how things progress.

Thanks again!


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


Cliff White <w5cnw@...>
 

Did you try setting the trigger to line or external?

Respectfully,
Cliff White, W5CNW
w5cnw@...

On 04/10/2013 10:04 PM, d.sligar wrote:
 

Thank you, Steve.
Just one comment, I have a dual trace plugin (53/54 K) as well as the
53/54 C. Neither of these gives a sweep, so I maybe can eliminate the pickoff circuits. (?)
Otherwise, I'll try what you suggest. I do think it's too soon to see this one ascend (descend?) to scope heaven.

I feel a bit over my head with this, but I'm not ready to give up. I'll let you (and the group) know how things progress.

Thanks again!
> >
> > 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
> >
> > >
> >
> >
>



David Sligar
 

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@yahoogroups.com, Cliff White <w5cnw@...> 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@yahoogroups.com <mailto:TekScopes%40yahoogroups.com>,
David Sligar <d.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


Cliff White <w5cnw@...>
 

Mine's also blue, probably P11, and only says "532" w/o the 57. Strange.



On 04/10/2013 10:12 PM, d.sligar wrote:
 

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
> >
> > >
> >
> >
>



David Sligar
 

Hi, Cliff --
No trigger setting has any effect on the beam (spot). No settings were changed from the day before, when I used the scope normally. The sweep just wasn't there Friday morning when I powered up.
Thanks,
David

--- In TekScopes@yahoogroups.com, Cliff White <w5cnw@...> wrote:

Did you try setting the trigger to line or external?

Respectfully,
Cliff White, W5CNW
w5cnw@... <mailto:w5cnw@...>
On 04/10/2013 10:04 PM, d.sligar wrote:

Thank you, Steve.
Just one comment, I have a dual trace plugin (53/54 K) as well as the
53/54 C. Neither of these gives a sweep, so I maybe can eliminate the
pickoff circuits. (?)
Otherwise, I'll try what you suggest. I do think it's too soon to see
this one ascend (descend?) to scope heaven.

I feel a bit over my head with this, but I'm not ready to give up.
I'll let you (and the group) know how things progress.

Thanks again!

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


Cliff White <w5cnw@...>
 

If you connect a dc voltmeter (preferably analog) to the sawtooth out jack, then set the sweep speed to the slowest it goes, can you see the voltage changing as a ramp? You might also try the same thing with the delayed gate out.


Respectfully,
Cliff White, W5CNW
w5cnw@...

On 04/11/2013 12:19 AM, d.sligar wrote:
 

Hi, Cliff --
No trigger setting has any effect on the beam (spot). No settings were changed from the day before, when I used the scope normally. The sweep just wasn't there Friday morning when I powered up.
Thanks,
David

--- In TekScopes@..., Cliff White wrote:
>
> Did you try setting the trigger to line or external?
>
> Respectfully,
> Cliff White, W5CNW
> w5cnw@...
> On 04/10/2013 10:04 PM, d.sligar wrote:
> >
> > Thank you, Steve.
> > Just one comment, I have a dual trace plugin (53/54 K) as well as the
> > 53/54 C. Neither of these gives a sweep, so I maybe can eliminate the
> > pickoff circuits. (?)
> > Otherwise, I'll try what you suggest. I do think it's too soon to see
> > this one ascend (descend?) to scope heaven.
> >
> > I feel a bit over my head with this, but I'm not ready to give up.
> > I'll let you (and the group) know how things progress.
> >
> > Thanks again!
> > > >
> > > > 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
> > > >
> > > > >
> > > >
> > > >
> > >
> >
> >
>



Cliff White <w5cnw@...>
 

One other thing I just noticed: yours has a extra toggle switch below the external horizontal input, and what looks like an extra light above it. What do those labels say for those two? Mine has neither, but is still a P11.


Respectfully,
Cliff White, W5CNW
w5cnw@...

On 04/10/2013 10:14 PM, Cliff White wrote:
 

Mine's also blue, probably P11, and only says "532" w/o the 57. Strange.



On 04/10/2013 10:12 PM, d.sligar wrote:
 

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
> >
> > >
> >
> >
>




Tim Phillips <tim@...>
 

from Tim P (UK)
I think that is a single-shot option - the original 532 didn't have one.
Some of them may have had P7 phosphors - the 'scope was popular
in the BioMed / Engineering fields, where 5MHz was plenty.
The Delayed  Gate was useful for driving Stimulators.
Tim
 

----- Original Message -----
Sent: Thursday, April 11, 2013 4:51 PM
Subject: Re: [TekScopes] Re: TEK 532 --

 

One other thing I just noticed: yours has a extra toggle switch below the external horizontal input, and what looks like an extra light above it. What do those labels say for those two? Mine has neither, but is still a P11.


Respectfully,
Cliff White, W5CNW
w5cnw@...
On 04/10/2013 10:14 PM, Cliff White wrote:
 

Mine's also blue, probably P11, and only says "532" w/o the 57. Strange.



On 04/10/2013 10:12 PM, d.sligar wrote:
 

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
> >
> > >
> >
> >
>




David Sligar
 

Hi, Cliff --
I did this, sawtooth out jack is steady at ~ 19 volts, delayed gate out, zero. I switched to "Single Sweep" (speed at 1 cm/sec) and saw the spot move to the right -- once. After a few seconds, spot is stationary, whether on single sweep or normal. Looks like the problem is solidifying. Are these clues?
Thanks!!
David

--- In TekScopes@yahoogroups.com, Cliff White <w5cnw@...> wrote:

If you connect a dc voltmeter (preferably analog) to the sawtooth out
jack, then set the sweep speed to the slowest it goes, can you see the
voltage changing as a ramp? You might also try the same thing with the
delayed gate out.


Respectfully,
Cliff White, W5CNW
w5cnw@... <mailto:w5cnw@...>
On 04/11/2013 12:19 AM, d.sligar wrote:

Hi, Cliff --
No trigger setting has any effect on the beam (spot). No settings were
changed from the day before, when I used the scope normally. The sweep
just wasn't there Friday morning when I powered up.
Thanks,
David

--- In TekScopes@yahoogroups.com <mailto:TekScopes%40yahoogroups.com>,
Cliff White <w5cnw@> wrote:

Did you try setting the trigger to line or external?

Respectfully,
Cliff White, W5CNW
w5cnw@ <mailto:w5cnw@>
On 04/10/2013 10:04 PM, d.sligar wrote:

Thank you, Steve.
Just one comment, I have a dual trace plugin (53/54 K) as well as the
53/54 C. Neither of these gives a sweep, so I maybe can eliminate the
pickoff circuits. (?)
Otherwise, I'll try what you suggest. I do think it's too soon to see
this one ascend (descend?) to scope heaven.

I feel a bit over my head with this, but I'm not ready to give up.
I'll let you (and the group) know how things progress.

Thanks again!

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


David Sligar
 

The toggle switch is "Single Sweep / Normal". Not an extra light, it's a button, label "Reset"

--- In TekScopes@yahoogroups.com, Cliff White <w5cnw@...> wrote:

One other thing I just noticed: yours has a extra toggle switch below
the external horizontal input, and what looks like an extra light above
it. What do those labels say for those two? Mine has neither, but is
still a P11.


Respectfully,
Cliff White, W5CNW
w5cnw@... <mailto:w5cnw@...>
On 04/10/2013 10:14 PM, Cliff White wrote:

Mine's also blue, probably P11, and only says "532" w/o the 57. Strange.



On 04/10/2013 10:12 PM, d.sligar wrote:

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@yahoogroups.com
<mailto:TekScopes%40yahoogroups.com>, Cliff White <w5cnw@> 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@yahoogroups.com
<mailto:TekScopes%40yahoogroups.com>
<mailto:TekScopes%40yahoogroups.com>,
David Sligar <d.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


David Sligar
 

I believe mine has the P7.

--- In TekScopes@yahoogroups.com, "Tim Phillips" <tim@...> wrote:

from Tim P (UK)
I think that is a single-shot option - the original 532 didn't have one.
Some of them may have had P7 phosphors - the 'scope was popular
in the BioMed / Engineering fields, where 5MHz was plenty.
The Delayed Gate was useful for driving Stimulators.
Tim

----- Original Message -----
From: Cliff White
To: TekScopes@yahoogroups.com
Sent: Thursday, April 11, 2013 4:51 PM
Subject: Re: [TekScopes] Re: TEK 532 --




One other thing I just noticed: yours has a extra toggle switch below the external horizontal input, and what looks like an extra light above it. What do those labels say for those two? Mine has neither, but is still a P11.



Respectfully,
Cliff White, W5CNW
w5cnw@...
On 04/10/2013 10:14 PM, Cliff White wrote:



Mine's also blue, probably P11, and only says "532" w/o the 57. Strange.





On 04/10/2013 10:12 PM, d.sligar wrote:


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@yahoogroups.com, Cliff White <w5cnw@> 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@yahoogroups.com <mailto:TekScopes%40yahoogroups.com>,
> > David Sligar <d.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
> >
> > >
> >
> >
>


Cliff White <w5cnw@...>
 

I think the "-57" on yours is the single sweep option, mine doesn't have that, so I'll just have to guess. Are you saying the single sweep works? If so, is that repeatable? Or did it just do it that once? If it's repeatable, what does the voltage on the sawtooth jack do when the dot is moving?

I'm not sure if mine is P7 or P11, I just know that it's blue. :)


Respectfully,
Cliff White, W5CNW
w5cnw@...

On 04/11/2013 12:59 PM, d.sligar wrote:
 

Hi, Cliff --
I did this, sawtooth out jack is steady at ~ 19 volts, delayed gate out, zero. I switched to "Single Sweep" (speed at 1 cm/sec) and saw the spot move to the right -- once. After a few seconds, spot is stationary, whether on single sweep or normal. Looks like the problem is solidifying. Are these clues?
Thanks!!
David

--- In TekScopes@..., Cliff White wrote:
>
> If you connect a dc voltmeter (preferably analog) to the sawtooth out
> jack, then set the sweep speed to the slowest it goes, can you see the
> voltage changing as a ramp? You might also try the same thing with the
> delayed gate out.
>
>
> Respectfully,
> Cliff White, W5CNW
> w5cnw@...
> On 04/11/2013 12:19 AM, d.sligar wrote:
> >
> > Hi, Cliff --
> > No trigger setting has any effect on the beam (spot). No settings were
> > changed from the day before, when I used the scope normally. The sweep
> > just wasn't there Friday morning when I powered up.
> > Thanks,
> > David
> >
> > --- In TekScopes@... ,
> > Cliff White wrote:
> > >
> > > Did you try setting the trigger to line or external?
> > >
> > > Respectfully,
> > > Cliff White, W5CNW
> > > w5cnw@
> > > On 04/10/2013 10:04 PM, d.sligar wrote:
> > > >
> > > > Thank you, Steve.
> > > > Just one comment, I have a dual trace plugin (53/54 K) as well as the
> > > > 53/54 C. Neither of these gives a sweep, so I maybe can eliminate the
> > > > pickoff circuits. (?)
> > > > Otherwise, I'll try what you suggest. I do think it's too soon to see
> > > > this one ascend (descend?) to scope heaven.
> > > >
> > > > I feel a bit over my head with this, but I'm not ready to give up.
> > > > I'll let you (and the group) know how things progress.
> > > >
> > > > Thanks again!
> > > > > >
> > > > > > 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
> > > > > >
> > > > > > >
> > > > > >
> > > > > >
> > > > >
> > > >
> > > >
> > >
> >
> >
>



ditter2
 

--- In TekScopes@yahoogroups.com, "d.sligar" <d.sligar@...> wrote:

Hi, Cliff --
I did this, sawtooth out jack is steady at ~ 19 volts, delayed gate out, zero. I switched to "Single Sweep" (speed at 1 cm/sec) and saw the spot move to the right -- once. After a few seconds, spot is stationary, whether on single sweep or normal. Looks like the problem is solidifying. Are these clues?
Thanks!!
David
David,

I think you are getting close. If you had seen a single sweep, then the miller integrator / sweep generator is probably functioning. This points to the trigger, or possibly the multivibrator portion of the sweep circuit that initiates and resets the sweep (V430 and associated circuits).

Try probing some of the points I accidently misposted to the thread on the member with a dead 515A this morning:

If you have another scope, set the 532 trigger to one of the Line positions (+ or -), with the trigger level knob near the center and stabilty set to auto. Set the time base to a medium to fast sweep (1 ms/div or faster) This should rearm the trigger before each new trigger pulse.

Look at pin 6 on V306 (trigger comparator), then pin 1 of V320 (trigger shaper). You should see something like a square wave at V306, then a sharper pulse at V320 with a period of 16.6 ms (assuming you have 60 Hz power - 20 ms if 50 Hz). If this is good move on to the time base. If not try swapping one of these tubes (where you don't see the signal).

My schematics don't show any signals or voltages, and the 532 topology is somewhat different from other 53x/54x scopes. So if your problem is in the multivibrator area, I will need to study the schematic more to determins what you should be seeing.

Let us know what the trigger circuit shows.

- Steve


David Sligar
 

Ooooh! Pain, after a fashion. I went back out to the shop to check the grid voltage on the comparator (V308, 6U8), turned on the scope, and it worked! Sweep is back, !!!!?????. I did change one setting -- the Triggering Mode, from Automatic to AC Fast. But formerly I always had this set to AC Fast -- before / during the "incident" -- and now, if I go back to Automatic I lose the sweep, but, as I say, I don't operate in this position normally anyway. Does this provide any clue to what's going on? Maybe has a bearing on my marginal sync?
All in all, it's a mystery to me. By the way, the sawtooth signal varies between some low number and about 90 volts, now. Seems reasonable.
Thanks for your help,
David

--- In TekScopes@yahoogroups.com, Cliff White <w5cnw@...> wrote:

I think the "-57" on yours is the single sweep option, mine doesn't have
that, so I'll just have to guess. Are you saying the single sweep works?
If so, is that repeatable? Or did it just do it that once? If it's
repeatable, what does the voltage on the sawtooth jack do when the dot
is moving?

I'm not sure if mine is P7 or P11, I just know that it's blue. :)


Respectfully,
Cliff White, W5CNW
w5cnw@... <mailto:w5cnw@...>
On 04/11/2013 12:59 PM, d.sligar wrote:

Hi, Cliff --
I did this, sawtooth out jack is steady at ~ 19 volts, delayed gate
out, zero. I switched to "Single Sweep" (speed at 1 cm/sec) and saw
the spot move to the right -- once. After a few seconds, spot is
stationary, whether on single sweep or normal. Looks like the problem
is solidifying. Are these clues?
Thanks!!
David

--- In TekScopes@yahoogroups.com <mailto:TekScopes%40yahoogroups.com>,
Cliff White <w5cnw@> wrote:

If you connect a dc voltmeter (preferably analog) to the sawtooth out
jack, then set the sweep speed to the slowest it goes, can you see the
voltage changing as a ramp? You might also try the same thing with the
delayed gate out.


Respectfully,
Cliff White, W5CNW
w5cnw@ <mailto:w5cnw@>
On 04/11/2013 12:19 AM, d.sligar wrote:

Hi, Cliff --
No trigger setting has any effect on the beam (spot). No settings
were
changed from the day before, when I used the scope normally. The
sweep
just wasn't there Friday morning when I powered up.
Thanks,
David

--- In TekScopes@yahoogroups.com
<mailto:TekScopes%40yahoogroups.com>
<mailto:TekScopes%40yahoogroups.com>,
Cliff White <w5cnw@> wrote:

Did you try setting the trigger to line or external?

Respectfully,
Cliff White, W5CNW
w5cnw@ <mailto:w5cnw@>
On 04/10/2013 10:04 PM, d.sligar wrote:

Thank you, Steve.
Just one comment, I have a dual trace plugin (53/54 K) as well
as the
53/54 C. Neither of these gives a sweep, so I maybe can
eliminate the
pickoff circuits. (?)
Otherwise, I'll try what you suggest. I do think it's too soon
to see
this one ascend (descend?) to scope heaven.

I feel a bit over my head with this, but I'm not ready to give up.
I'll let you (and the group) know how things progress.

Thanks again!

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


David Sligar
 

Thanks, Steve -- I don't have another scope, or I might not be so energetic about this one! (These are mostly tools, to me, though I do have affection for them as themselves.)
You probably see my previous post to Cliff -- the rascal suddenly started to work again. Happened just as I switched Sweep Mode from Automatic, though the sweep had been missing on all modes yesterday.
Mysterious, exasperating! Intermittent problems are the worst, though I am very grateful to have my operational scope back, and have already used it for its intended purpose.
If this gives you any clues, I'd be grateful.
David

--- In TekScopes@yahoogroups.com, "Steve" <ditter2@...> wrote:

--- In TekScopes@yahoogroups.com, "d.sligar" <d.sligar@> wrote:

Hi, Cliff --
I did this, sawtooth out jack is steady at ~ 19 volts, delayed gate out, zero. I switched to "Single Sweep" (speed at 1 cm/sec) and saw the spot move to the right -- once. After a few seconds, spot is stationary, whether on single sweep or normal. Looks like the problem is solidifying. Are these clues?
Thanks!!
David
David,

I think you are getting close. If you had seen a single sweep, then the miller integrator / sweep generator is probably functioning. This points to the trigger, or possibly the multivibrator portion of the sweep circuit that initiates and resets the sweep (V430 and associated circuits).

Try probing some of the points I accidently misposted to the thread on the member with a dead 515A this morning:

If you have another scope, set the 532 trigger to one of the Line positions (+ or -), with the trigger level knob near the center and stabilty set to auto. Set the time base to a medium to fast sweep (1 ms/div or faster) This should rearm the trigger before each new trigger pulse.

Look at pin 6 on V306 (trigger comparator), then pin 1 of V320 (trigger shaper). You should see something like a square wave at V306, then a sharper pulse at V320 with a period of 16.6 ms (assuming you have 60 Hz power - 20 ms if 50 Hz). If this is good move on to the time base. If not try swapping one of these tubes (where you don't see the signal).

My schematics don't show any signals or voltages, and the 532 topology is somewhat different from other 53x/54x scopes. So if your problem is in the multivibrator area, I will need to study the schematic more to determins what you should be seeing.

Let us know what the trigger circuit shows.

- Steve


David Sligar
 

A couple weeks ago I had trouble with losing the sweep on my scope. After two or three days of tube checking, voltage reading, control adjustments, and visuals I could find nothing obvious.

Then, suddenly, the sweep came back, and I posted to that effect. I have been using the 532 since then, getting readable traces of square waves I'm working with. But all is not well. The sweep controls must be adjusted very carefully -- much more so than before -- in order to get a good trace. Seems like there is only one setting that will work. And, depending on the waveform, often the scope simply will not lock in and the traces are unreadable.

I hope I've not used up all my advice credit yet. If anyone has an idea where I should start looking, I'd be grateful.

David