Date   

Re: Oregon Public Broadcasting "Oregon Experience - The Spirit of Tek"

Dave Brown
 

There is no format or region code on the DVD or box. We have confirmed that it is an NTSC format All Region DVD and it should play on most computers and PAL DVD players. As such we have opened up the sales worldwide. We just wanted to be sure before we offered it for sale in other regions.


Re: Oregon Public Broadcasting "Oregon Experience - The Spirit of Tek"

Dave Brown
 

We haven't opened up sales outside of the USA until we verified what the region codes were on the DVD. We're just in the process of doing that now.

Dave


Re: Scope-Mobile Cart Model 3 Disassemble

radioconnection@...
 

Phillips or Posidrive.drivers for 90 percent, and a socket set for top shelf swivel hardware and for wheels... I just put one together that was shipped via UPS. The front cast handles are easy to damage, be careful of the cast aluminum parts. UPS broke a handle and I had to have it MIG welded. As I recall most of the hardware is metric.


Re: tektronix475 fault hv section? no trace

unclebanjoman
 

Aside the "short" (it's the filament as David pointed out), you didn't say if with CRT socket unplugged and U1321 disconnected the oscillator works or not and the correct voltage at the cathode of CR1329 is present, as I told you in my last post...

Max


Re: PG506 ISSUES Need some experienced minds!

Mlynch001
 

Albert,

The excellent advice is appreciated. I will make some measurements, tests and observations based on your previous post and get back to you.

--
Michael Lynch
Dardanelle, AR


Re: TDS 620A vs. TDS 620B questions and repair inquiry

Harvey White
 

On 6/10/2019 10:36 AM, David Berlind wrote:
Harvey,

Thanks for the validation on the video. I'm glad someone with a good eye
took a look. When you said "So your 1 Khz calibrator requires a decent
frequency response to (gasp!) 10 Khz," are you saying that a 100Mhz probe
won't work as well as a 10Khz probe when reading off the calibrator?
Nope.  There are no 10KHz probes, and I'm not sure I've ever heard of a 100 KHz probe.  My comment was that with either an X1 probe or any X10 I've ever seen, the squareness of the waveform has so few requirements, that almost any X10 probe would work.

Go for a higher frequency square wave, and you'll see some differences.

For a 500 Mhz scope, the best squarewave you'll see is about 50 Mhz.  Go above that, and with everything right, the squarewave will start to round due to the scope bandwidth.  Everything right means a direct connection to the scope and a 50 ohm termination (to minimize capacitance).

If you have a squarewave generator, try this with a number of different scopes, and see what's going on.  Bandwidth limit your scope and see the difference.




In the video, did you notice the fluctuation in frequency? It wasn't
sitting on exactly 1Khz. There's a bit of back and forth movement. Is that
normal and if not, what's the fix (not that I desperately need to fix
that.. but it'd be good to know).
Remember that there's a voltage quantization problem, you only have so many displayable levels vertically, but you also have only so many horizontal slots to divide up the waveform anyway. Depending on where the scope decides the waveform starts (and ends), some of this is pretty normal.

Harvey



Thanks.

On Sun, Jun 9, 2019 at 5:37 PM Harvey White <madyn@dragonworks.info> wrote:

Very rough rule of thumb on square waves. A "decent" square wave
requires response to about 10x the fundamental frequency. (it only has
odd harmonics). So your 1 Khz calibrator requires a decent frequency
response to (gasp!) 10 Khz.

Still, the frequency compensation on most adjustable probes is decent
enough when done at 1 Khz. For other frequencies and the like, the
"flat top" of the square wave will likely be insufficient. That also
varies per probe. The P6015 high voltage probe has at least six or
seven separate adjustments for frequency response and flatness.

Normally, though, what Tek did is to optimize pulse response over
flatness of frequency response.

Video looks good to me.

Harvey


On 6/9/2019 1:29 PM, David Berlind wrote:
As I await all your answers, I started with page 1 of the manual this
morning and am liking the functionality. Compared to my initial
quick-plug-it-in see if it works the other day, things went much
better. The first thing I did was a factory reset (following the
manual's instructions of course). This may have fixed a few things.
Working with the probe calibration signal, here's a video of what I
observed after selecting some measurements for display. I'm using
some100Mhz probes at 1x.

https://photos.app.goo.gl/8Lt8pPpUCVgPPUw1A


On June 9, 2019 11:42:15 AM "Stephen Hanselman" <kc4sw.io@kc4sw.com>
wrote:

I don’t have a lot of knowledge but two things. In the 540, 540A,
540C, etc the “ “ and “A” speak a different HPIB language from the
“B” and “C”. If a lab says calibration for $300 they “may” hook it up
and make sure the readings are close but not much else.

I don’t know what a fully automated set could do, I do all my
calibrations manually with the Tek software. The 540B takes about 5
hours to do a good job. If you were close I say bring it by and turn
you loose on my software.

Regards,

Stephen Hanselman
Datagate Systems, LLC
3107 North Deer Run Road #24
Carson City, Nevada, 89701
(775) 882-5117 office
(775) 720-6020 mobile
s.hanselman@datagatesystems.com
www.datagatesystems.com
a Service Disabled, Veteran Owned Small Business
DISCLAIMER:
This e-mail and any attachments are intended only for use by the
addressee(s) named herein and may contain legally privileged and/or
proprietary information. If you are not the intended recipient, any
dissemination, distribution or copying of this e-mail and any
attachments is strictly prohibited. If you have received this e-mail
in error, please immediately notify me and permanently delete the
original and all copies and printouts of this e-mail and any
attachments.
On Jun 9, 2019, at 08:25, David Berlind <david@berlind.org> wrote:


Hi all,


After starting my oscilloscope journey with analog scopes for the
last two years and seeing some of what the digital scopes could do
(for example, maths), I had been watching my local marketplaces
carefully for a good price on a digital scope in working condition.
I recently picked up at TDS 620B for $85 and am now beginning the
journey of getting to know it. I will be posting video of its
behavior which I think may be in need of correction based on initial
observations.. and I am of course looking for advice. But I may be
wrong about that. I will work on eliminating other issues first
(configuration, line noise, etc.).


My first inquiry involves four questions:


1. I could not locate an online manual for the 620B. I found the
Technical Reference and printed that out. But in terms of the User
Manual, I could only find a manual for the 620A (could just be bad
Googling skills). So, I downloaded and printed that out. Now, I'm
trying to ascertain whether the 620A manual is for the most part
applicable (should have done this before killing a tree to print it
I guess) or whether the 620A is different enough from the 620B that
the manual doesn't apply. I've been looking for some way to compare
the two side by side (I found some differently formatted data and
specification sheets so apples to apples isn't perfect, but there's
some overlapping data to get some jist). But I thought it would be
prudent to toss the question out to this group because maybe someone
will just know and can summarize key differences and how that
impacts anything (usage, probes, etc).


2. I'll take any suggestions from you pros on great ways to get
started with this scope. Configurations to try. Shortcuts. Anything
that will fast-track my introduction to expert operation of the scope.


3. The 620B did not come with any probes when I purchased it. I
noticed from the 620A documentation that that scope originally came
with a 6139A probe which lead me into an exploration of probe
characteristics. That probe's specs appear to match the 500Mhz
capability of the scope. Over the last two years, I haven't thought
much about the probes themselves. Just been using what I acquired
along the way and things seem to work. So, in the spirit of rooting
out any configuration problems before needing to effect any repairs,
to what extent could basic probe differences impact behavior? For
example, I have some basic 1X/10x probes (which might not be rated
for 500Mhz) that work nicely on my 7603. What incompatibilities
could exist between these probes and the 620B such that I might get
unexpected/inaccurate behavior?


4. Wondering whether it might be best and faster just to have the
pros take a look at the scope, I have inquired with a local
calibration service as to the cost of a "tune-up." The estimate
just for calibration for was over $300 (way more than the cost of
the scope). It dawned on me that one option might be to pay someone
in this group to bring her up to snuff. This is for hobbyist work
(repairing amps, radios, etc) so it's not like I need a certificate.
Is there someone here who does that sort of thing?


Thank you.


David








Re: tektronix475 fault hv section? no trace

David Holland
 

1 & 14 are the filament connections and expected to be “shorted”

On Mon, Jun 10, 2019 at 12:13 PM Jiří Kauč <jiri-kauc@hotmail.com> wrote:

So i prove there is a short between pin 1 and 14. Its in crt. May u advise
me how to continue, because this issue is way beyond my skills. Right now a
i think i end.



--
Sent from a Mobile iAnnoyance thingy, please pardon any typos


Re: tektronix475 fault hv section? no trace

Jiří Kauč
 

So i prove there is a short between pin 1 and 14. Its in crt. May u advise me how to continue, because this issue is way beyond my skills. Right now a i think i end.


Re: TDS 620A vs. TDS 620B questions and repair inquiry

Siggi
 

On Mon, Jun 10, 2019 at 10:37 AM David Berlind <david@berlind.org> wrote:

In the video, did you notice the fluctuation in frequency? It wasn't
sitting on exactly 1Khz. There's a bit of back and forth movement. Is that
normal and if not, what's the fix (not that I desperately need to fix
that.. but it'd be good to know).
Note that the automatic frequency measurement is just measuring the length
of the first cycle of the recorded waveform. To give it the best chance for
good measurement, do your best to fill the screen with a single waveform -
so higher sampling rate, higher vertical sensitivity. Then drop the noise
by turning on the BW limit - here you'll be just fine with 20MHz bandwidth.
This is the same as you'd want to do if you were making a manual
measurement on an analog scope.

There are scopes that have a built-in hardware counter, but I don't think
any of the TDS scopes do.


Re: TDS 620A vs. TDS 620B questions and repair inquiry

Chuck Harris <cfharris@...>
 

A little study of Fourier transforms would do you wonders...

A square wave, shown in the time domain, is, well, square....
you know the picture... Up, straight across, down, straight
across, up...

If you instead take a tunable receiver, with a narrow bandwidth,
and feed it the square wave, as you tune the receiver from DC up
in frequency, you will notice that there are only signals at the
fundamental frequency of the square wave, and at the odd harmonics
of the fundamental frequency. Further, you will notice that the
amplitude of the signals the receiver sees diminishes rapidly
as the harmonic number goes up: actually by 1/harmonic number, so
by the time you get to the 9th harmonic, the amplitude is 1/9'th of
the fundamental's amplitude...

If you were an experimental researcher around Fourier's time, you
would probably try lots of things, like see what happens to your
picture of a square wave when you
eliminate all of the harmonics above a certain point...say, the
9th harmonic.

You would find, that if the harmonics below the 10th were kept, the
square wave would look pretty much like a square wave. It would have
some rounding of the leading and trailing corners, and some ripple
on the tops and bottom, but it would be a pretty good square wave.

Fast forward to a modern tektronix scope with its 1KHz square wave
scope probe calibrator signal.

If you display this signal on any scope that has a bandwidth of 10KHz
or more, it will look very much like a square wave... just as experimenters
around Fourier's time would have predicted.

When Harvey wrote "So your 1 Khz calibrator requires a decent frequency
response to (gasp!) 10 Khz"... he was indicating that the scope's square
wave calibration signal isn't much of a stress test for any modern scope,
as it could be displayed adequately on a scope with only 10KHz bandwidth.

-Chuck Harris

David Berlind wrote:

Harvey,

Thanks for the validation on the video. I'm glad someone with a good eye
took a look. When you said "So your 1 Khz calibrator requires a decent
frequency response to (gasp!) 10 Khz," are you saying that a 100Mhz probe
won't work as well as a 10Khz probe when reading off the calibrator?

In the video, did you notice the fluctuation in frequency? It wasn't
sitting on exactly 1Khz. There's a bit of back and forth movement. Is that
normal and if not, what's the fix (not that I desperately need to fix
that.. but it'd be good to know).

Thanks.


Re: TDS 620A vs. TDS 620B questions and repair inquiry

David Berlind
 

Harvey,

Thanks for the validation on the video. I'm glad someone with a good eye
took a look. When you said "So your 1 Khz calibrator requires a decent
frequency response to (gasp!) 10 Khz," are you saying that a 100Mhz probe
won't work as well as a 10Khz probe when reading off the calibrator?

In the video, did you notice the fluctuation in frequency? It wasn't
sitting on exactly 1Khz. There's a bit of back and forth movement. Is that
normal and if not, what's the fix (not that I desperately need to fix
that.. but it'd be good to know).

Thanks.

On Sun, Jun 9, 2019 at 5:37 PM Harvey White <madyn@dragonworks.info> wrote:


Very rough rule of thumb on square waves. A "decent" square wave
requires response to about 10x the fundamental frequency. (it only has
odd harmonics). So your 1 Khz calibrator requires a decent frequency
response to (gasp!) 10 Khz.

Still, the frequency compensation on most adjustable probes is decent
enough when done at 1 Khz. For other frequencies and the like, the
"flat top" of the square wave will likely be insufficient. That also
varies per probe. The P6015 high voltage probe has at least six or
seven separate adjustments for frequency response and flatness.

Normally, though, what Tek did is to optimize pulse response over
flatness of frequency response.

Video looks good to me.

Harvey


On 6/9/2019 1:29 PM, David Berlind wrote:
As I await all your answers, I started with page 1 of the manual this
morning and am liking the functionality. Compared to my initial
quick-plug-it-in see if it works the other day, things went much
better. The first thing I did was a factory reset (following the
manual's instructions of course). This may have fixed a few things.
Working with the probe calibration signal, here's a video of what I
observed after selecting some measurements for display. I'm using
some100Mhz probes at 1x.

https://photos.app.goo.gl/8Lt8pPpUCVgPPUw1A


On June 9, 2019 11:42:15 AM "Stephen Hanselman" <kc4sw.io@kc4sw.com>
wrote:

I don’t have a lot of knowledge but two things. In the 540, 540A,
540C, etc the “ “ and “A” speak a different HPIB language from the
“B” and “C”. If a lab says calibration for $300 they “may” hook it up
and make sure the readings are close but not much else.

I don’t know what a fully automated set could do, I do all my
calibrations manually with the Tek software. The 540B takes about 5
hours to do a good job. If you were close I say bring it by and turn
you loose on my software.

Regards,

Stephen Hanselman
Datagate Systems, LLC
3107 North Deer Run Road #24
Carson City, Nevada, 89701
(775) 882-5117 office
(775) 720-6020 mobile
s.hanselman@datagatesystems.com
www.datagatesystems.com
a Service Disabled, Veteran Owned Small Business
DISCLAIMER:
This e-mail and any attachments are intended only for use by the
addressee(s) named herein and may contain legally privileged and/or
proprietary information. If you are not the intended recipient, any
dissemination, distribution or copying of this e-mail and any
attachments is strictly prohibited. If you have received this e-mail
in error, please immediately notify me and permanently delete the
original and all copies and printouts of this e-mail and any
attachments.
On Jun 9, 2019, at 08:25, David Berlind <david@berlind.org> wrote:


Hi all,


After starting my oscilloscope journey with analog scopes for the
last two years and seeing some of what the digital scopes could do
(for example, maths), I had been watching my local marketplaces
carefully for a good price on a digital scope in working condition.
I recently picked up at TDS 620B for $85 and am now beginning the
journey of getting to know it. I will be posting video of its
behavior which I think may be in need of correction based on initial
observations.. and I am of course looking for advice. But I may be
wrong about that. I will work on eliminating other issues first
(configuration, line noise, etc.).


My first inquiry involves four questions:


1. I could not locate an online manual for the 620B. I found the
Technical Reference and printed that out. But in terms of the User
Manual, I could only find a manual for the 620A (could just be bad
Googling skills). So, I downloaded and printed that out. Now, I'm
trying to ascertain whether the 620A manual is for the most part
applicable (should have done this before killing a tree to print it
I guess) or whether the 620A is different enough from the 620B that
the manual doesn't apply. I've been looking for some way to compare
the two side by side (I found some differently formatted data and
specification sheets so apples to apples isn't perfect, but there's
some overlapping data to get some jist). But I thought it would be
prudent to toss the question out to this group because maybe someone
will just know and can summarize key differences and how that
impacts anything (usage, probes, etc).


2. I'll take any suggestions from you pros on great ways to get
started with this scope. Configurations to try. Shortcuts. Anything
that will fast-track my introduction to expert operation of the scope.


3. The 620B did not come with any probes when I purchased it. I
noticed from the 620A documentation that that scope originally came
with a 6139A probe which lead me into an exploration of probe
characteristics. That probe's specs appear to match the 500Mhz
capability of the scope. Over the last two years, I haven't thought
much about the probes themselves. Just been using what I acquired
along the way and things seem to work. So, in the spirit of rooting
out any configuration problems before needing to effect any repairs,
to what extent could basic probe differences impact behavior? For
example, I have some basic 1X/10x probes (which might not be rated
for 500Mhz) that work nicely on my 7603. What incompatibilities
could exist between these probes and the 620B such that I might get
unexpected/inaccurate behavior?


4. Wondering whether it might be best and faster just to have the
pros take a look at the scope, I have inquired with a local
calibration service as to the cost of a "tune-up." The estimate
just for calibration for was over $300 (way more than the cost of
the scope). It dawned on me that one option might be to pay someone
in this group to bring her up to snuff. This is for hobbyist work
(repairing amps, radios, etc) so it's not like I need a certificate.
Is there someone here who does that sort of thing?


Thank you.


David









Re: EP53A Gain Set Adpater

 

I doubt that you will ever find a EP53A. Look for a TU-7 which is the EP53A and a pulser combined to cal the 535/545 scopes. Actually the TU-7 works for most 500 series scopes. How many plugins do you have for your 535? The TU-7 is used to standardize the gain of the 535 mainframe as well as adjust the risetime response of the 500 series scopes. So if you only have 1 plugin you can just set the gain of the plugin as outlined in the manual for the plugin and everything will be just fine. If you have more than 1 plugin then just pick one as the "standard" and then adjust the others gain to match. Read the description of the TU-7 on http://w140.com/tekwiki/wiki/1M1. This will give you a better idea of what this plugin does.
The TU-7 is really only necessary if you have multiple plugins being used with many 500 series scopes.
Bill


Re: Oregon Public Broadcasting "Oregon Experience - The Spirit of Tek"

Brian Cockburn
 

And for those outside of the USA, where the DVD doesn't ship, the URL for streaming is: https://watch.opb.org/video/oregon-experience-the-spirit-of-tek/


Re: PG506 ISSUES Need some experienced minds!

Albert Otten
 

Michael,

Sure you can do several measurements when the supply is -63 V, regardless whether that value is correct or not. First thing to look at is the voltages across the zener diodes. In my case these are 5.1 V and 2.5 V.
My supply goes down to -73 V when Ampl is at max. For comparison, here are my DMM readings when I adjust the supply to your -63 V.
"-72V" -63 V
gate -54.7 V
C800 -44.7 V
"+5V" +5.21 V
pin 2 +2.83 V
pin 3 +2.94 V (2 and 3 should in theory be equal)
pin 6 +7.30 V

I realized now that I made a mistake when I wrote this:

The unloaded -63 V looks good, but could just as well be the end of the regulation range (with 14
V feedback to CR27) while actually there is no regulation.
CR27 is a low impedance point and regulation is more current driven than voltage driven. Pin 6 remains more or less constant, varying to slightly over +8 V is maximum. Hence the difference C800 vs gate remains more or less constant at about 10 V over the amplitude range. With 50R load and amplitude at MAX I measured 8 V difference.

I hope this gives you some guidance.

Albert


On Mon, Jun 10, 2019 at 03:45 AM, Mlynch001 wrote:


The whole schematic gives me a headache! sort of like peering into a bowl of
spaghetti and trying to pick out the ends of all the strands. This was
certainly NOT written for a woefully under prepared individual, such as
myself. The good thing is that I am starting to just understand how this
stuff works. I am going to go back and make some more measurements on output.
I don't have numbers, but I am almost certain the that the Amplitude Knob had
zero effect on the output voltage. I have already started to go through the
<5> schematic and check voltages at all the components. I have also started
testing the components systematically with the DMM. First the CR's, VR's and
working toward the transistors. I just don't have my head totally wrapped
around how this thing functions. All this "negative" voltage is foreign to
me. I keep hoping that a "light bulb" will pop on, but i fear that is not
going to happen. I think that I have a suitable replacement part for U840,
but I want to check for other faults first. I am going to try to digest your
last reply and study this issue in detail, that is going to take some time.
It is important to me to get this thing working, and I am certainly NOT afraid
to attempt this. One thing that I do know is what a great tool the PG506 can
be, so that is a great motivation. I also am eager to learn more about
electronics in general. I appreciate that you are putting in a great amount
of time and effort to help me.

Sincerely,
--
Michael Lynch
Dardanelle, AR


Re: PG506 ISSUES Need some experienced minds!

Mlynch001
 

On Sun, Jun 9, 2019 at 03:50 PM, Albert Otten wrote:


Michael,

If you got a headache from the High Ampl diagram <5> you're in good comany.
The way this diagram is drawn is terrible. We complained about this already
many years ago. And you are lucky to have the B-04 up version since the
earlier diagram also showed circuit modifications (and errors around VR792).
For now I roughly redraw the diagram (once more) in my own way.
It's a pity that you only measured with Ampl set to MAX. The unloaded -63 V
looks good, but could just as well be the end of the regulation range (with 14
V feedback to CR27) while actually there is no regulation. I hoped you would
find an increasingly more negative "-72V" when you rotate Ampl further
clockwise. A setting mid-way or so would be good to measure at more points in
the circuits.
Anyway, -6 V when loaded is for sure not negative enough. (BTW "loaded" has
not to be read in the sense that the output transistors have to deliver more
power. The form a constant current supply (when on) to feed 600R || load.)
The gate of Q758 is at about a 9 V more positive voltage than "-72V" (VR792 +
VR790 + CR734). The gate is always negative because current supplier Q790 has
its base at ground.
When the output is on, the drain of Q758 is about 1.5 V more negative negative
than the output voltage and the C800 voltage. That C800 voltage is compared
with the gate voltage by U840. The voltage dividers to +5V, 100k to 4k53, are
the same but R827 (to ground) and R840 (to pin 6) destroy the symmetry. U840
regulates the voltage difference between pin 2 and pin 3 to zero. But then the
gate has to be much more negative than C800 (and thus the drain) and the
difference increases when the output voltage amplitude (and pin 6 are higher.
(Or, when a load is attached at some Ampl setting, the difference between
drain and gate decreases.)
I was a bit surprised by this when I did measurements in my PG506. Only one
situation so far: unloaded, output amplitude set to 6 V:
"-72V" was about -21 V,
gate about -12.5 V,
drain about -7 V. when on, slightly positive when off.

When your unloaded "-72V" doesn't change with Ampl setting then something is
really wrong. Could be the opamp U840, or open Q800, open Q792, you name it...
Possibly the fasted way to find the fault(s) is to check as far as possible,
without desoldering, all transistors and diodes with the DMM diode check
function . You might be lucky!

Albert

On Sat, Jun 8, 2019 at 11:56 PM, Mlynch001 wrote:


Albert,

You are so right in saying that there are a lot of potential faults. I'm
just
happy that I got it back to the point where I am at the moment. If we can
take it one step at a time and in an organized manner, I believe that will
yield the best results. Similar to the 100V supply, once I can zero in on a
specific area, I will have a better chance of locating the problem. All of
these current and voltage regulators just give me chills. Wondering how
many
of these might be bad?

Here are the results from the output of the High Amplitude section:

PG506 Settings
Function High Ampl
Period 1uS 1 MHz
Variable Full ccw
Pulse Amplitude MAX

Scope TDS460A

Channel 1 DC Coupling into 1 M Ohm

Used "AUTOSET"

Screen readout shows -63.52 DCV No wave form is visible, checked both AC
and DC Coupled.

Channel 1 DC Coupled into 1 M Ohm channel with 50Ohm termination. .1 uSec
2V
range

Single linear trace at just under -3 1/4 divisions and readout shows -6.45
DCV.

VARIABLE Knob has no effect on the voltage level present.

R790 has no affect on voltage.

Switching PERIOD to other ranges does not affect affect the voltage.

I hope this all makes sense. If not, feel free to ask questions and
correct
me as needed.

I sincerely appreciate your guidance and advice.
--
Michael Lynch
Dardanelle, AR
Albert,

The whole schematic gives me a headache! sort of like peering into a bowl of spaghetti and trying to pick out the ends of all the strands. This was certainly NOT written for a woefully under prepared individual, such as myself. The good thing is that I am starting to just understand how this stuff works. I am going to go back and make some more measurements on output. I don't have numbers, but I am almost certain the that the Amplitude Knob had zero effect on the output voltage. I have already started to go through the <5> schematic and check voltages at all the components. I have also started testing the components systematically with the DMM. First the CR's, VR's and working toward the transistors. I just don't have my head totally wrapped around how this thing functions. All this "negative" voltage is foreign to me. I keep hoping that a "light bulb" will pop on, but i fear that is not going to happen. I think that I have a suitable replacement part for U840, but I want to check for other faults first. I am going to try to digest your last reply and study this issue in detail, that is going to take some time. It is important to me to get this thing working, and I am certainly NOT afraid to attempt this. One thing that I do know is what a great tool the PG506 can be, so that is a great motivation. I also am eager to learn more about electronics in general. I appreciate that you are putting in a great amount of time and effort to help me.

Sincerely,
--
Michael Lynch
Dardanelle, AR


EP53A Gain Set Adpater

Brenda
 

Hello everyone! I have been wanting to get my 535A into calibration, but according to the manual I need an EP53A gain set adapter which I will also use with my 533A and my 545A when the time comes. However, I am not finding much information about these units. Does anyone have a schematic or even know if one could be made from scratch? Or is there a way to work around needing this gain set adapter? I looked in the forums and I did not find anything about it. I did find a pdf file on 013-0005-00 and in the parts list very few parts with a .1uf 400V capacitor and a 220K 1/2W resistor and a lug.

Please help as I would like to get my 535A into service! Thanks so much!

Brenda


Oregon Public Broadcasting "Oregon Experience - The Spirit of Tek"

Dave Brown
 

If you haven't seen the OPB "Oregon Experience - The Spirit of Tek" the museum now has a limited number of DVDs for sale on our eBay store. OPB showed this recently and does stream this video but I'm sure you will want to own your own copy. All proceeds support the museum. https://vintagetek.org/opb-oregon-experience-the-spirit-of-tek/


Re: TDS 620A vs. TDS 620B questions and repair inquiry

Stephen Hanselman
 

Thanks, that is a great deal I didn’t know about the the 600’s. Find out what the ground shipping is and we can talk off line. I would like to see a 600. I see a lot of 500’s and would like to see what the 600 is like.

Regards,

Stephen Hanselman
Datagate Systems, LLC
3107 North Deer Run Road #24
Carson City, Nevada, 89701
(775) 882-5117 office
(775) 720-6020 mobile
s.hanselman@datagatesystems.com
www.datagatesystems.com
a Service Disabled, Veteran Owned Small Business
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On Jun 9, 2019, at 16:06, nonIonizing EMF <nonionizingemf@gmail.com> wrote:

On Sun, Jun 9, 2019 at 07:25 AM, David Berlind wrote:


3. The 620B did not come with any probes when I purchased it. I noticed from
the 620A documentation that that scope originally came with a 6139A probe
which lead me into an exploration of probe characteristics. That probe's specs
appear to match the 500Mhz capability of the scope. Over the last two years, I
haven't thought much about the probes themselves. Just been using what I
acquired along the way and things seem to work. So, in the spirit of rooting
out any configuration problems before needing to effect any repairs, to what
extent could basic probe differences impact behavior? For example, I have some
basic 1X/10x probes (which might not be rated for 500Mhz) that work nicely on
my 7603. What incompatibilities could exist between these probes and the 620B
such that I might get unexpected/inaccurate behavior?
Here are some references for those not on the FB Old Tek Scopes group, might not have seen the latest post regarding Tek probes or haven't seen these references before ( https://www.facebook.com/groups/oldtekscopes/permalink/435036140617897/ ) :

http://www.barrytech.com/tektronix/probes/tekprobes.html


I'm thinking these are older probes references so might not be pertinent though may have some utility from the info in the links:

https://web.archive.org/web/20180307162334/http://www.reprise.com/host/tektronix/reference/default.asp (two links might provide some details)

http://w140.com/tek_probe_crossref_1990.pdf (more of an older scope reference)


I've not gotten around to verifying the "A", "B", "C" and "D" model codes... though seems from general reading there are TDS-5XX/6XX/7XX family associated capabilities detailed (I forget at the time being).



Re: TDS 620A vs. TDS 620B questions and repair inquiry

nonIonizing EMF
 

On Sun, Jun 9, 2019 at 07:25 AM, David Berlind wrote:


3. The 620B did not come with any probes when I purchased it. I noticed from
the 620A documentation that that scope originally came with a 6139A probe
which lead me into an exploration of probe characteristics. That probe's specs
appear to match the 500Mhz capability of the scope. Over the last two years, I
haven't thought much about the probes themselves. Just been using what I
acquired along the way and things seem to work. So, in the spirit of rooting
out any configuration problems before needing to effect any repairs, to what
extent could basic probe differences impact behavior? For example, I have some
basic 1X/10x probes (which might not be rated for 500Mhz) that work nicely on
my 7603. What incompatibilities could exist between these probes and the 620B
such that I might get unexpected/inaccurate behavior?
Here are some references for those not on the FB Old Tek Scopes group, might not have seen the latest post regarding Tek probes or haven't seen these references before ( https://www.facebook.com/groups/oldtekscopes/permalink/435036140617897/ ) :

http://www.barrytech.com/tektronix/probes/tekprobes.html


I'm thinking these are older probes references so might not be pertinent though may have some utility from the info in the links:

https://web.archive.org/web/20180307162334/http://www.reprise.com/host/tektronix/reference/default.asp (two links might provide some details)

http://w140.com/tek_probe_crossref_1990.pdf (more of an older scope reference)


I've not gotten around to verifying the "A", "B", "C" and "D" model codes... though seems from general reading there are TDS-5XX/6XX/7XX family associated capabilities detailed (I forget at the time being).


Re: TDS 620A vs. TDS 620B questions and repair inquiry

Siggi
 

On Sun, Jun 9, 2019 at 10:25 AM David Berlind <david@berlind.org> wrote:

1. I could not locate an online manual for the 620B. I found the Technical
Reference and printed that out. But in terms of the User Manual, I could
only find a manual for the 620A (could just be bad Googling skills). So, I
downloaded and printed that out. Now, I'm trying to ascertain whether the
620A manual is for the most part applicable (should have done this before
killing a tree to print it I guess) or whether the 620A is different enough
from the 620B that the manual doesn't apply.
I think a significant difference between the 600A and 600B generations is
that the Bs have peak detect acquisition mode. This allows them to catch
1ns (?) peaks even at slow sweep speeds.

Note that the TDS600-series scopes are CCD-based (like the 2430-2440s of
old), whereas the TDS500/700-series are ADC-based. The CCD scopes don't
slow down the acquisition rate as you turn on more channels, but they don't
have equivalent time nor hi-res sampling modes.
They also tend to have more limited record length, and I believe they have
more dead time than the 500/700s. This is due to the fact that while they
capture into the CCD at a very quick rate, the contents of the CCD are then
digitized at a pretty leisurely rate after a trigger is detected.

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