Gents,

Thanks, all. I really don’t know if it’s the pot, or the combined switch, that is frozen. One or the other. I can get spray into the pot, but it still won’t move. The rotary switch on the back, however, is sealed tightly. I will continue to attempt to get spray into the fool switches. There are two of these combined pot/switches in the 453. Stay tuned.

Richard

I know how you feel! I still have two GPSDOs and a couple of Rb units sitting around (just in case), but although having at least seven stable zeros is nice, it doesn't make the scope you're working on any more accurate.  Unsubscribing from Timenuts made my life easier...
-Dave
On Friday, July 31, 2020, 09:43:19 AM PDT, Stephen <stephen.nabet@gmail.com> wrote:
On Fri, Jul 31, 2020 at 05:36 AM, Tom Gardner wrote:

Ah. A perfectionist tweaker :)

Yes, I am.  I like precision.  Maybe I do have an OCD.  😂

A quick skim of the schematic makes me think I would expect to see offsets on
the outputs.

Ok.

It is a time calibrator, not an amplitude calibrator. I'd be satisfied if the
peak-peak amplitudes are acceptably large.

Honestly, I haven’t had the time to check everything yet, but for what I’m using it for (mostly .1ms and 1ms time marks), it works like a charm.

It's worth building, if only partially.

As designed, it allows you to check AC voltage and phasing, bulk
supplies, power transistor beta (not directly), and provides a +5 and
+/- 15 volt general purpose supply.

Tektronix may or may not have made these, I don't know.  The description
suggests that it was intended for internal use as a testing tool.

If you do not want or need the regulated supplies, then bringing out the
transistors individually allows using a transistor tester.  A plugin
strip for a 5 volt regulated supply and pickoffs for the other pins (to
go to a front panel) could be made fairly easily, there are some designs
already that simply bring out the pins.  What you do with those pins is
up to you.

It's a design where you could throw a bit of technology at it and
automate some things, but that's an "up to you" kind of thing.

The pots are in the feedback circuit for the regulators and should
adjust the 15 volt supplies.

Harvey


On 7/31/2020 1:43 PM, Colin Herbert via groups.io wrote:

Does anyone know any more about this item? It has the ID# 067-1201-99
and I have the Tek "manual" for it as a pdf. There was also another
document which was termed "Construction Note". Did Tek make any of
these, or did they see them as totally for people to make themselves?
The "manual" that I have has the ID# 061-3001-00. The "Construction
Note" (which I also have a pdf of) seems to be exactly that as well as
being a Service Manual in that it gives some assembly information that
would be useful to a constructor. Both documents include a schematic,
but I cannot find any information on the function of two preset pots
R127 and R227. These are described in the Replaceable Electric Parts
List as "non-wirewound, 5K0, 20%, 0.5W" and I am assuming that they
set the +15VDC and -15VDC output levels respectively.

It looks like an interesting item.

Colin.

It's worth building, if only partially.
As designed, it allows you to check AC voltage and phasing, bulk supplies, power transistor beta (not directly), and provides a +5 and +/- 15 volt general purpose supply.
Tektronix may or may not have made these, I don't know.  The description suggests that it was intended for internal use as a testing tool.
If you do not want or need the regulated supplies, then bringing out the transistors individually allows using a transistor tester.  A plugin strip for a 5 volt regulated supply and pickoffs for the other pins (to go to a front panel) could be made fairly easily, there are some designs already that simply bring out the pins.  What you do with those pins is up to you.
It's a design where you could throw a bit of technology at it and automate some things, but that's an "up to you" kind of thing.
The pots are in the feedback circuit for the regulators and should adjust the 15 volt supplies.
Harvey
On 7/31/2020 1:43 PM, Colin Herbert via groups.io wrote:

Does anyone know any more about this item? It has the ID# 067-1201-99 and I have the Tek "manual" for it as a pdf. There was also another document which was termed "Construction Note". Did Tek make any of these, or did they see them as totally for people to make themselves? The "manual" that I have has the ID# 061-3001-00. The "Construction Note" (which I also have a pdf of) seems to be exactly that as well as being a Service Manual in that it gives some assembly information that would be useful to a constructor. Both documents include a schematic, but I cannot find any information on the function of two preset pots R127 and R227. These are described in the Replaceable Electric Parts List as "non-wirewound, 5K0, 20%, 0.5W" and I am assuming that they set the +15VDC and -15VDC output levels respectively.

It looks like an interesting item.

Colin.

From: "Gary Robert Bosworth" <grbosworth@gmail.com>
To: TekScopes@groups.io
Sent: Friday, July 31, 2020 1:58:55 PM
Subject: Re: [TekScopes] Stuck switches on 453

Be extremely careful when drilling into potentiometers. You will almost
always drill into the resistive wire or element and ruin the pot. I cannot
stress this enough. Gary

On Fri, Jul 31, 2020, 07:21 Abc Xyz <yawrdanza@gmail.com> wrote:

Richard,

I know a guy who told me he immerses Stuck Potentiometers/Switches in
Solution to free them up. I personally have not Witnessed the
Procedure...so take it for what its worth.
Also, I have Read where one Drills a Very Small Hole in the Body of the
Mechanism and Dribbles Solution in...again, I have never tried it or seen
it done.
I have tried turning the Scope where the Potentiometer Shaft is Vertical
and place a Few Drops of Deoxit on the Shaft itself thinking Gravity would
pull the Cleaner down into the Part...didn't work for me but it may be one
of those things where a Great Deal More Patience is Needed!

JR

On Thu, Jul 30, 2020, 10:46 PM Richard P via groups.io <wb5nen=
yahoo.com@groups.io> wrote:

I’ve used my Model 453 for years for basic audio but it has always had a
problem. The rotary switches on each of the variable sweep rate
potentiometers (one on the front panel, and one on the side) are frozen

in

the uncalibrated positions. Therefore, the “Uncal A or B” light is

forever

lit, and the sweep rate for either A or B is uncalibrated. These combined
switch/potentiometers are like a rotary volume control with an on/off
switch. But stuck. I’ve tried to loosen them up with DeOxit, contact
cleaner, even liquid wrench. But these guys are pretty-well sealed up,

and

access to them in the 453 chassis is very challenging. I can see the

shafts

moving a bit, so I believe the problem is inside the switch/pot

assemblies,

not that shafts are stuck in bushings. Any thoughts on this one?

Richard

Richard,

I know a guy who told me he immerses Stuck Potentiometers/Switches in
Solution to free them up. I personally have not Witnessed the
Procedure...so take it for what its worth.
Also, I have Read where one Drills a Very Small Hole in the Body of the
Mechanism and Dribbles Solution in...again, I have never tried it or seen
it done.
I have tried turning the Scope where the Potentiometer Shaft is Vertical
and place a Few Drops of Deoxit on the Shaft itself thinking Gravity would
pull the Cleaner down into the Part...didn't work for me but it may be one
of those things where a Great Deal More Patience is Needed!

JR

On Thu, Jul 30, 2020, 10:46 PM Richard P via groups.io <wb5nen=
yahoo.com@groups.io> wrote:

I’ve used my Model 453 for years for basic audio but it has always had a
problem. The rotary switches on each of the variable sweep rate
potentiometers (one on the front panel, and one on the side) are frozen

in

the uncalibrated positions. Therefore, the “Uncal A or B” light is

forever

lit, and the sweep rate for either A or B is uncalibrated. These combined
switch/potentiometers are like a rotary volume control with an on/off
switch. But stuck. I’ve tried to loosen them up with DeOxit, contact
cleaner, even liquid wrench. But these guys are pretty-well sealed up,

and

access to them in the 453 chassis is very challenging. I can see the

shafts

moving a bit, so I believe the problem is inside the switch/pot

assemblies,

not that shafts are stuck in bushings. Any thoughts on this one?

Richard

Does anyone know any more about this item? It has the ID# 067-1201-99 and I have the Tek "manual" for it as a pdf. There was also another document which was termed "Construction Note". Did Tek make any of these, or did they see them as totally for people to make themselves? The "manual" that I have has the ID# 061-3001-00. The "Construction Note" (which I also have a pdf of) seems to be exactly that as well as being a Service Manual in that it gives some assembly information that would be useful to a constructor. Both documents include a schematic, but I cannot find any information on the function of two preset pots R127 and R227. These are described in the Replaceable Electric Parts List as "non-wirewound, 5K0, 20%, 0.5W" and I am assuming that they set the +15VDC and -15VDC output levels respectively.

It looks like an interesting item.

Colin.

The config number is WP2221/62, and it has it's own serial number.  I seem to
recall that these were part of a "system" as opposed to modified plugin- is my
memory correct?

Ah. A perfectionist tweaker :)

A quick skim of the schematic makes me think I would expect to see offsets on
the outputs.

It is a time calibrator, not an amplitude calibrator. I'd be satisfied if the
peak-peak amplitudes are acceptably large.