Date   

DC503A S1810 repair/replacement ?

Andy Warner
 

Bought a DC503A a while back (as-is) and finally got around to debugging
its strange behavior.
Turns out the function switch (S1810) is missing a set of wipers.

See: https://groups.io/g/TekScopes/photo/251456/0

In the photo, you can see the two plastic stumps where the wiper is
supposed to be.
It was nowhere to be found, I guess someone must have disassembled the
switch before me to remove the wreckage.

Any suggestions on repair/replacement strategies ?
Anyone got a dead DC503A they would be willing to sell me all or part of
(if so, please contact me off list at: andyw at pobox dot com)
--
Andy


Re: TM 500 Power Module Tester and Utility Power Supply

Dave Casey
 

I have one that was made by Tek (has a Tek serial number). It has a single,
purpose built Tek PWB in it, which has been numbered "670-8715-00" in
Sharpie. The two trimmers in mine are Bourns 386 series. All the front
panel controls and I/O are connected to the PWB with hookup wire (including
the Scope output). The board is laid out such that all these connection
points are near the front panel end of the PWB, and they all appear to be
labeled in the etch layer.

Dave Casey

On Fri, Jul 31, 2020 at 12:43 PM Colin Herbert via groups.io <colingherbert=
blueyonder.co.uk@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.




Re: DC503 Not Working

Richard R. Pope
 

Hello all,
I had someone do this with a Mazda RX-2. The Mazdas of that day and age had an amp meter in the dash. There was a 50 amp main fuse under the hood. The wiring for the amp meter ran through the main harness under the hood and through the main harness under the dash. These fuses were $5 each and that was expensive in the early 1970s.
Well this car started blowing the main fuse so the owner replaced the fuse with a piece of coat hanger instead of finding the short. Well the results were predictable. He heavily damaged both the harness' under the hood and under the dash. The alternator had some shorted diodes and that is what was blowing the fuse. It wasn't pretty but the car didn't catch fire. Fortunately!
GOD Bless and Thanks,
rich!

On 7/31/2020 6:55 PM, Harvey White wrote:
It tells me that something is drawing too much current.

Generally, it's a tantalum capacitor. The tantalum may NOT read a dead short, only some do. It could read low, draw an amp on a circuit where the circuit was supposed to draw 100 ma. I'd want to remove the fuse, check the power current vs. the fuse rating. Use the 20 amp range on a meter.

If it's not a tantalum, then something ought to be getting rather hot in operation.

The previous owner "fixed" the problem the same way that an "expert" electrician fixes a power problem by putting a penny behind the fuse.

Harvey


Re: Stuck switches on 453

n4buq
 

I recently worked on a larger rotary switch on a piece of an old Fluke calibrator. The dried grease can really make those shafts quite hard to turn! The HP 8640B has a similar issue with its band switch and it is amazing how much better they work when cleaned and freshly lubricated.

Good luck with it.

Thanks,
Barry - N4BUQ

----- Original Message -----
From: "Richard P via groups.io" <wb5nen=yahoo.com@groups.io>
To: TekScopes@groups.io
Sent: Friday, July 31, 2020 5:04:37 PM
Subject: Re: [TekScopes] Stuck switches on 453

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




Re: DC503 Not Working

Harvey White
 

It tells me that something is drawing too much current.

Generally, it's a tantalum capacitor.  The tantalum may NOT read a dead short, only some do.  It could read low, draw an amp on a circuit where the circuit was supposed to draw 100 ma.  I'd want to remove the fuse, check the power current vs. the fuse rating. Use the 20 amp range on a meter.

If it's not a tantalum, then something ought to be getting rather hot in operation.

The previous owner "fixed" the problem the same way that an "expert" electrician fixes a power problem by putting a penny behind the fuse.

Harvey

On 7/31/2020 6:22 PM, Stephen wrote:
I changed the 2 caps, as someone suggested. I’ve rechecked the voltages, and they are all good.
I’ve also re-cleaned the sockets. And nothing has changed. I’m waiting to modify the JAMMA connector to checks all that you guys suggested.
However, I did notice something maybe worth mentioning, and that might give you experts a clue as to what’s not right:
1- The plugin fuse (Fast 2A), blows every once in a while when I power the TM on and off 5-10 seconds apart Or so, to check if the “0” comes on in the same position, or at all. The previous owner had soldered a 4A fuse. Maybe because he had the same problem and thought 2A wasn’t enough... I don’t know why he’d do that. Grrr...
Does that tell you something?



Re: Type 184

@0culus
 

It just needs to be better than the thing you’re calibrating...and it doesn’t take much to beat the accuracy of an analog scope timebase. I adjusted my 184’s crystal oven with the help of my GPSDO and HP 53310A. I was able to get 5 decimal places. Way overkill for calibrating scopes, but it’s cool that it can do that.

Sean


Re: TM 500 Power Module Tester and Utility Power Supply

 

On Fri, Jul 31, 2020 at 12:43 PM, Colin Herbert 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.
Colin,
The pots are Bi Technologies MODEL 72
3/8” Square Single Turn Cermet Trimming Potentiometer
https://www.mouser.com/datasheet/2/414/72-3497.pdf

Looks like any jelly bean trimmer would work,'

Cheers,
Dave M


Re: Type 184

Stephen
 

On Fri, Jul 31, 2020 at 05:56 AM, Dave Seiter wrote:


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
LOL


Re: DC503 Not Working

Stephen
 

I changed the 2 caps, as someone suggested. I’ve rechecked the voltages, and they are all good.
I’ve also re-cleaned the sockets. And nothing has changed. I’m waiting to modify the JAMMA connector to checks all that you guys suggested.
However, I did notice something maybe worth mentioning, and that might give you experts a clue as to what’s not right:
1- The plugin fuse (Fast 2A), blows every once in a while when I power the TM on and off 5-10 seconds apart Or so, to check if the “0” comes on in the same position, or at all. The previous owner had soldered a 4A fuse. Maybe because he had the same problem and thought 2A wasn’t enough... I don’t know why he’d do that. Grrr...
Does that tell you something?


Re: Stuck switches on 453

Harvey White
 

If you can loosen the coupler on the switch, perhaps the pot shaft can rotate?  That might narrow it down.

Harvey

On 7/31/2020 6:04 PM, Richard P via groups.io wrote:
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



Re: Type 184

Stephen
 

On Fri, Jul 31, 2020 at 10:41 AM, Eric wrote:

Interleaved answers.


I have done a cal on the one that I have and it was a weird one. On mine
it did need some adjustment.
I think mine is just fine. 27Hz is really nothing, and way below specs. Given the tight tolerances And German built quality of this HAMEG counter, even if it’s 50Hz (which I highly doubt it is), I’m still good specs wise.
Mine probably needs some minor adjustments as well, I guess. I haven’t checked anything else yet beside the time base.

I love the build quality of the 184 and the ability to use double time marks + trigger.
Yep. It’s pretty amazing, I must say.

> Some scope cals call for trigger time with 2 different time marks. only thing i know that will do
that is the 184.
I’m no expert. This is the first and only Time Mark Generator that I’ve ever had, but I guess you’re right.



Zen

On 7/31/2020 12:55 PM, Dave Seiter wrote:
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@...> 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.





Re: Stuck switches on 453

Richard P
 

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


Re: Type 184

Eric
 

I have done a cal on the one that I have and it was a weird one. On mine it did need some adjustment. I love the build quality of the 184 and the ability to use double time marks + trigger. Some scope cals call for trigger time with 2 different time marks. only thing i know that will do that is the 184


Zen

On 7/31/2020 12:55 PM, Dave Seiter wrote:
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@...> 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.




Re: Looking for a 28JR200-1 BNC connector

cmdrdick42@...
 

I can not identify any BNC connector via a number, and don't have a FG502, but I have thousands of BNC connectors here and could probably locate a duplicate. Could you send photos of the front and side views with a caliper laying next to it.I'm sure that I'll be able to help.CmdrDick

On Friday, July 31, 2020, 02:49:51 PM EDT, Jared Cabot via groups.io <jaredcabot=protonmail.com@groups.io> wrote:

I'm currently restoring a few TM series modules and I found one of the BNC connectors in my FG502 function generator has a damaged center contact.

Does anyone have a 28JR200-1 BNC connector in good condition they can throw in an envelope and sent to me in Japan? I have Paypal standing by. :)

Thanks!
Jared


Re: TM 500 Power Module Tester and Utility Power Supply

Dave Seiter
 

It's on tekwiki, the last entry in the TM500 section.

On Friday, July 31, 2020, 12:39:58 PM PDT, Larry McDavid <lmcdavid@...> wrote:

Someone please provide the locations where these documents are available
or actual links to the documents. It is not helpful to talk about the
documents and not link to them.

Larry


On 7/31/2020 11:21 AM, Harvey White wrote:
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.





--
Best wishes,

Larry McDavid W6FUB
Anaheim, California  (SE of Los Angeles, near Disneyland)


Re: TM 500 Power Module Tester and Utility Power Supply

Larry McDavid
 

Someone please provide the locations where these documents are available or actual links to the documents. It is not helpful to talk about the documents and not link to them.

Larry

On 7/31/2020 11:21 AM, Harvey White wrote:
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.



--
Best wishes,

Larry McDavid W6FUB
Anaheim, California (SE of Los Angeles, near Disneyland)


Re: Stuck switches on 453

n4buq
 

If those are Clarostat pots, I have had good success just disassembling, cleaning, and reassembling those.

Thanks,
Barry - N4BUQ

----- Original Message -----
From: "Gary Robert Bosworth" <@grbosworth>
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@...> 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








Re: Stuck switches on 453

Gary Robert Bosworth
 

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@...> 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






Looking for a 28JR200-1 BNC connector

Jared Cabot
 

I'm currently restoring a few TM series modules and I found one of the BNC connectors in my FG502 function generator has a damaged center contact.

Does anyone have a 28JR200-1 BNC connector in good condition they can throw in an envelope and sent to me in Japan? I have Paypal standing by. :)

Thanks!
Jared


Re: TM 500 Power Module Tester and Utility Power Supply

Harvey White
 

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.