Date   

Re: Restoring a type 547 and 422 scopes (also my introduction to the group=

Craig Sawyers <c.sawyers@...>
 

Ok, will try to find that info and see if I can figure it out.
But still... please shoot me an email as soon as you get back to winding please.
Thanks a bunch.
Nic.
Tried to send you the winding spec, but the mail refuses to send - just sits in the outbox.

Craig


Re: Custom ICs 155-0196-00 and 155-0216-00 needed

unclebanjoman
 

I apologize for my delayed reply.

Thank for your replies, David and /Håkan.

I don't know those video monitor but I imagine they are hard to find!


If some forum's user had a 7D20 or any other instrument (for spare or not working) containing a pair of 155-0216-00 I am willing to buy it.

Thanks,
Max


Re: Restoring a type 547 and 422 scopes (also my introduction to the group=

The Guy
 

Ok, will try to find that info and see if I can figure it out.
But still... please shoot me an email as soon as you get back to winding please.
Thanks a bunch.
Nic.

On Tuesday, August 29, 2017 12:57 PM, "Chuck Harris cfharris@erols.com [TekScopes]" <TekScopes@yahoogroups.com> wrote:


  Winding isn't hard, it is, however tricky.

The HV is merciless in its quest to find your
mistakes, forcing you to trash your work and
start over.

The winding sheet is available in the file section
of this group, somewhere. If you can't find it,
I could send it to you directly.

Tektronix wound the transformers using #38AWG
double formvar wire. The windings are mostly
done bifilar, meaning two wires are set down as
if they were one, but each wire is a different
winding. The primary is also wound in #38 bifilar,
but with the wires in parallel.

Tektronix used a self supporting universal, or
basket wind. You have seen a similar wind if you
have seen a spool of twine where the twine goes
back and forth, and forms a regular criss-cross
pattern that locks it together, without a spool.

You can wind by hand, on a bobbin, in single layers
that are individually insulated with a layer of tape.
Tedious, but very doable.

What is hard, is making an exact duplicate of what
tektronix did, and that is what I do.

-Chuck Harris

nicolas.sog@yahoo.com [TekScopes] wrote:
Hey there Chuck!

Thanks for chiming in.


Will test that tube screen out as you suggested.


Do you think I could do the rewinding myself? Is it difficult? Maybe you could
teach me a thing or two... so there can be two 547 HV trannie rewinders in the
world ;) ...let me know.


If you don't have the time to teach me out a little please let me know as soon as
you get back to rewinding please!


Take care and I hope the hammering eases out a bit ;)


cheers,


Nic.
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Re: Restoring a type 547 and 422 scopes (also my introduction to the group=

Chuck Harris
 

Winding isn't hard, it is, however tricky.

The HV is merciless in its quest to find your
mistakes, forcing you to trash your work and
start over.

The winding sheet is available in the file section
of this group, somewhere. If you can't find it,
I could send it to you directly.

Tektronix wound the transformers using #38AWG
double formvar wire. The windings are mostly
done bifilar, meaning two wires are set down as
if they were one, but each wire is a different
winding. The primary is also wound in #38 bifilar,
but with the wires in parallel.

Tektronix used a self supporting universal, or
basket wind. You have seen a similar wind if you
have seen a spool of twine where the twine goes
back and forth, and forms a regular criss-cross
pattern that locks it together, without a spool.

You can wind by hand, on a bobbin, in single layers
that are individually insulated with a layer of tape.
Tedious, but very doable.

What is hard, is making an exact duplicate of what
tektronix did, and that is what I do.

-Chuck Harris

nicolas.sog@yahoo.com [TekScopes] wrote:

Hey there Chuck!

Thanks for chiming in.


Will test that tube screen out as you suggested.


Do you think I could do the rewinding myself? Is it difficult? Maybe you could
teach me a thing or two... so there can be two 547 HV trannie rewinders in the
world ;) ...let me know.


If you don't have the time to teach me out a little please let me know as soon as
you get back to rewinding please!


Take care and I hope the hammering eases out a bit ;)


cheers,


Nic.


Re: Restoring a type 547 and 422 scopes (also my introduction to the group=

The Guy
 

Congrats. looks fine - maybe needs some probe compensation?

Hi John,


I am a scope noob.... what do you mean by probe compensation? Why would i need that?


Sorry, I am learning as fast as i can.


Cheers,


Re: Restoring a type 547 and 422 scopes (also my introduction to the group=

The Guy
 

Hey there Chuck!

Thanks for chiming in.


Will test that tube screen out as you suggested.


Do you think I could do the rewinding myself? Is it difficult? Maybe you could teach me a thing or two... so there can be two 547 HV trannie rewinders in the world ;) ...let me know.


If you don't have the time to teach me out a little please let me know as soon as you get back to rewinding please!


Take care and I hope the hammering eases out a bit ;)


cheers,


Nic.


Re: Restoring a type 547 and 422 scopes (also my introduction to the group=

John Griessen
 

On 08/28/2017 10:14 PM, nicolas.sog@yahoo.com [TekScopes] wrote:
https://youtu.be/KMRNyncKq6Q https://youtu.be/KMRNyncKq6Q
Congrats. looks fine - maybe needs some probe compensation?


Re: Restoring a type 547 and 422 scopes (also my introduction to the group=

Chuck Harris
 

Connect a DVM to the screen grid (pin 8) of the
6AU5 HV oscillator. It should be somewhere around
80V.

I suspect that you will see it at 95V, and heading
to the moon as the beam goes away. If you have a
late 547, it will have a protective zener diode on
the screen that limits the runaway voltage to 125V.
If you have an older scope, without that zener, the
screen will go right on up until it burns out the
6AU5 from over dissipation.

Most of the time, a 547 that has been left in storage,
can clean itself up a bit, if you turn the scope off
to cool down when the current starts to run away, and
then repeat the process.

The scope that got me started winding would go about
15 minutes, and as I played with it, the time it would
run kept increasing slowly until it would run full time.

Then I would leave it off for a month, and we would be
back to 15 minutes... I got tired of the game, and
start winding.

I will be back, but for right now, I am hammered with
tasks that take priority over winding. Winding was
never meant to be a profit item, just a break even
thing... so it has to yield to more important work.

-Chuck Harris

nicolas.sog@yahoo.com [TekScopes] wrote:

I would like to add that if I let the scope cool like for 2 or 3 minutes then the
trace is bright and beautiful again.... for another minute.





------------------------------------ Posted by: nicolas.sog@yahoo.com


Re: Hi I'm Lennart

The Guy
 

Good luck with the fixin' by the way... first thing you got to do is get the service manuals. Can't do anything without'em.
Cheers.

On Tuesday, August 29, 2017 12:17 PM, Nicolas Olmos <nicolas.sog@yahoo.com> wrote:


Hey Lennart! How is it going...
I got accepted the other day also, AND I practice the same hobby ;)Also came here looking for advice for repairing my two beautiful tek scopes. I got a 422 and a really awesome hybrid (tube/transistor) driven Type 547 scope. So we are pretty much in the same "wavelength" lol.
This 547 has like 40 tubes in it! Ain't that great?
Cheers.

On Tuesday, August 29, 2017 12:06 PM, "lennart.j.hbg@gmail.com [TekScopes]" <TekScopes@yahoogroups.com> wrote:


  Hello everyone!
Thanks for accepting me, glad to take part of the group.
My name is Lennart and I'm from souther part of Sweden.
My hobbies are building guitar amps, also woodworking cabinet etc.
Just bought 2 scope a 465 and a 2215. The 465 works like a charm
the 2215 won't trigger, well will look into that ASAP.

Thanks alot, and glad to be here.
Take care.

Lennart



[Non-text portions of this message have been removed]

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Re: Hi I'm Lennart

The Guy
 

Hey Lennart! How is it going...
I got accepted the other day also, AND I practice the same hobby ;)Also came here looking for advice for repairing my two beautiful tek scopes. I got a 422 and a really awesome hybrid (tube/transistor) driven Type 547 scope. So we are pretty much in the same "wavelength" lol.
This 547 has like 40 tubes in it! Ain't that great?
Cheers.

On Tuesday, August 29, 2017 12:06 PM, "lennart.j.hbg@gmail.com [TekScopes]" <TekScopes@yahoogroups.com> wrote:


  Hello everyone!
Thanks for accepting me, glad to take part of the group.
My name is Lennart and I'm from souther part of Sweden.
My hobbies are building guitar amps, also woodworking cabinet etc.
Just bought 2 scope a 465 and a 2215. The 465 works like a charm
the 2215 won't trigger, well will look into that ASAP.

Thanks alot, and glad to be here.
Take care.

Lennart



[Non-text portions of this message have been removed]

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[Non-text portions of this message have been removed]


Hi I'm Lennart

Lennart Jansson
 

Hello everyone!
Thanks for accepting me, glad to take part of the group.
My name is Lennart and I'm from souther part of Sweden.
My hobbies are building guitar amps, also woodworking cabinet etc.
Just bought 2 scope a 465 and a 2215. The 465 works like a charm
the 2215 won't trigger, well will look into that ASAP.

Thanks alot, and glad to be here.
Take care.

Lennart


Re: Restoring a type 547 and 422 scopes (also my introduction to the group=

The Guy
 

Hi Craig,

I've read here that Chuck has stopped rewinding transformers for a while... huge bummer!!


Help me Chuck! Please, i beg you! lol


Ok.... How about this tho?


https://richardsears.wordpress.com/2015/08/23/tektronix-547/ https://richardsears.wordpress.com/2015/08/23/tektronix-547/



Might work no?


Cheers.


Re: Restoring a type 547 and 422 scopes (also my introduction to the group=

Craig Sawyers <c.sawyers@...>
 

Alright, being that solved, the problem now is that the trace dims out completely (without any
bloom
or distortion) after like one minute. As it fades I keep turning the intensity knob until reaching
its fully
clockwise position to compensate for the dimming... but as said after a minute it is out.
Epoxy potted HT transformer that supplies the acceleration voltage to the CRT. Absolutely standard
with the 547 and other oscilloscopes of that era, like the 545B and early 576 curve tracer.

The only solution is to wait for Chuck Harris to chime in - he manufactures perfect replicas which are
wax potted; you have to disassemble your existing transformer and send him the two halves of the
ferrite core.

Craig


Re: Restoring a type 547 and 422 scopes (also my introduction to the group=

Dave Voorhis
 

On 29 Aug 2017, at 16:24, nicolas.sog@yahoo.com [TekScopes] <TekScopes@yahoogroups.com> wrote:

I would like to add that if I let the scope cool like for 2 or 3 minutes then the trace is bright and beautiful again.... for another minute.



Re: Restoring a type 547 and 422 scopes (also my introduction to the group=

The Guy
 

I would like to add that if I let the scope cool like for 2 or 3 minutes then the trace is bright and beautiful again.... for another minute.


Re: Intensity not working on 2465A

ti8jlh
 

Hello SiggiYou really know about this scopes. Thank you very much for your explanation and the troubleshooting. I have the service manual of this scope.This afternoon I will  start to look for your suggestions and study electronics around this circuit. I hope I don't need to make a calibration because I don't have the instruments for that.Joachim

-------- Ursprüngliche Nachricht --------
Von: "Sigurður Ásgeirsson siggi@undo.com [TekScopes]" <TekScopes@yahoogroups.com>
Datum: 29.08.2017 07:08 (GMT-06:00)
An: TekScopes@yahoogroups.com
Betreff: Re: [TekScopes] Intensity not working on 2465A


 









On Tue, 29 Aug 2017 at 00:00 Joachim Lange ti8jlh@gmail.com [TekScopes] <

TekScopes@yahoogroups.com> wrote:



The scope is a through hole version. Ripple looks good but the voltage
on TP2420 is 1,019V and on TP2421 is -0,933V.


This is great news - it means that there's something up with your DAC, its

reference current, or the MUX & S&H. If these voltages are off, then all

bets are off for the functionality of the scope. The 1.36V is used as

centerpoint for the DACs output voltages, so all your analog controls are

going to be off and lopsided when that's off.



The voltage of the Keeper Battery is 3,7V and the voltage over R2770 is
ca 0,2mV. But this is not very correct because sometimes it 0,0mV and
then it is 0,4 mV on the mV scale.
This sounds good - the main thing is that you're not observing excessive

current draw.



Maybe if I pull out one side of R2770 it is possible to get the mA
drain. But then the scope would not have a battery.
No don't do that - it looks like the keeper's doing fine. What's the date

code on it - out of curiosity?



Where are these voltages on the test points come from? Maybe there is
again a resistor that changed the value.
BTW: If you don't yet have a service manual, I can recommend the Artek

Manual scan - I have both the 2465 and the 2467 scans, and they're off

excellent quality.



The way these voltages come about is fairly convoluted. Let's walk through

it.



The DAC, U2101, is a current-mode device, and it takes an input reference

current.

The reference current is derived from the 10V REF input, and from R2013 -

which is a 0.1%, low TC resistor. The reference current can then be trimmed

by way of R2010 and the network around that trimmer. If the reference

current is low, the DACs outputs will be low also.



Start by measuring the voltage between pins 14 and 15 on U2101. As these

are the inputs of an opamp in negative feedback, the voltage difference

between those pins should be effectively zero. A visual inspection of the

circuit around R2013 would be in order, and maybe you can measure them

in-circuit, or at least measure the resistance from pins 14/15 to the 10V

rail (<=10k), to ground (<=10k) and to each other (<=5k), just to verify

that the network is connected and sound.



Now, the output of the DAC is a current that's converted to voltage by the

two load resistors R2520/R2521. Unfortunately the service manual I have

doesn't have the waveform you should see across those resistors, but if you

can measure that differentially with a scope, there is a spec somewhere for

the peak-to-peak values you should be seeing. We know the DC offset is

going to be wrong already, because TP2420 sets that.



The way the -1.25 reference voltage is derived, is that the DACs input is

set to a predefined code. The resultant output is sampled through U2521,

held by C2320, and buffered by U2420D. U2420A then creates the +1.36V

reference by ratio across the ground. The ratio of your voltages is right,

so we can assume that U2420A is good, I think.



Assuming you find nothing off in the DACs reference, your most likely

suspects would be



- U2521, a 4051 analog MUX.

These have been known to fail sometimes. The way to check is to probe

pin 3 and pin 13 at the same time. You should see a repeating waveform at

pin 3, and on pin 13 you should see one of the values from that waveform

held at DC. If the switch is leaky, you'll see the input waveform bleed

through it.

- A leaky C2321 or C2322.

You'll see droop in the DC value on pin 13 of U2521 and/or pin 12 of

U2420(D) that's periodic with the refresh rate of the voltage (I think I

remember 15ms period, but don't quote me on that).



If none of those are the culprit, then either U2420 is bad or struggling

because something is loading down the -1.25V. Let's eliminate the lot above

first, but on my 2467, VR2420 had gone short, and was pinning the -1.25V

reference to ground. This lead to no trace and a bunch of other symptoms

that led me around the merry go-around for a while :).


















[Non-text portions of this message have been removed]


Re: Restoring a type 547 and 422 scopes (also my introduction to the group=

The Guy
 

Ok, I thought i'd post how the issue was fixed for future reference. This is how it happened:

The horizontal amplifier's transistors Q554 and Q564 were out of whack (found that one following the troubleshooting method in the video Dave posted), so, they didn't pair well, out of balance so to speak... then what I did was to look at the schematics until I found another 2N2207 transistor somewhere in the circuit (actually the Q424 in schematic #7), took it out, took the Q554 and Q564 also out, grabbed my DMM, tested them, and voilà... two perfectly matched transistor back in Q554/Q564 positions and the 547 worked. Nice.



Alright, being that solved, the problem now is that the trace dims out completely (without any bloom or distortion) after like one minute. As it fades I keep turning the intensity knob until reaching its fully clockwise position to compensate for the dimming... but as said after a minute it is out.


Any ideas or pointers that could help me figure this one out?


Thank you.


Re: general question on XY mode on a 4 ch Tek TDS

Paul
 

Hi Gary,
thanks for taking the time. I'm encouraged by your answer. It actually sounds better .. sounds from your answer that I could have more than 2 XY curves on the same screen at the same time. I thought I would be limited to two in parallel but I read your answer as I could have 3 in parallel using ch1 as the X and Ch2, Ch3, C4 each as different Y-axis...
This would mean I could match up to 3 filters at the same time.


Thanks
Paul


Re: Intensity not working on 2465A

Siggi
 

On Tue, 29 Aug 2017 at 00:00 Joachim Lange ti8jlh@gmail.com [TekScopes] <
TekScopes@yahoogroups.com> wrote:



The scope is a through hole version. Ripple looks good but the voltage

on TP2420 is 1,019V and on TP2421 is -0,933V.
This is great news - it means that there's something up with your DAC, its
reference current, or the MUX & S&H. If these voltages are off, then all
bets are off for the functionality of the scope. The 1.36V is used as
centerpoint for the DACs output voltages, so all your analog controls are
going to be off and lopsided when that's off.

The voltage of the Keeper Battery is 3,7V and the voltage over R2770 is
ca 0,2mV. But this is not very correct because sometimes it 0,0mV and
then it is 0,4 mV on the mV scale.
This sounds good - the main thing is that you're not observing excessive
current draw.

Maybe if I pull out one side of R2770 it is possible to get the mA
drain. But then the scope would not have a battery.
No don't do that - it looks like the keeper's doing fine. What's the date
code on it - out of curiosity?

Where are these voltages on the test points come from? Maybe there is
again a resistor that changed the value.
BTW: If you don't yet have a service manual, I can recommend the Artek
Manual scan - I have both the 2465 and the 2467 scans, and they're off
excellent quality.

The way these voltages come about is fairly convoluted. Let's walk through
it.

The DAC, U2101, is a current-mode device, and it takes an input reference
current.
The reference current is derived from the 10V REF input, and from R2013 -
which is a 0.1%, low TC resistor. The reference current can then be trimmed
by way of R2010 and the network around that trimmer. If the reference
current is low, the DACs outputs will be low also.

Start by measuring the voltage between pins 14 and 15 on U2101. As these
are the inputs of an opamp in negative feedback, the voltage difference
between those pins should be effectively zero. A visual inspection of the
circuit around R2013 would be in order, and maybe you can measure them
in-circuit, or at least measure the resistance from pins 14/15 to the 10V
rail (<=10k), to ground (<=10k) and to each other (<=5k), just to verify
that the network is connected and sound.

Now, the output of the DAC is a current that's converted to voltage by the
two load resistors R2520/R2521. Unfortunately the service manual I have
doesn't have the waveform you should see across those resistors, but if you
can measure that differentially with a scope, there is a spec somewhere for
the peak-to-peak values you should be seeing. We know the DC offset is
going to be wrong already, because TP2420 sets that.

The way the -1.25 reference voltage is derived, is that the DACs input is
set to a predefined code. The resultant output is sampled through U2521,
held by C2320, and buffered by U2420D. U2420A then creates the +1.36V
reference by ratio across the ground. The ratio of your voltages is right,
so we can assume that U2420A is good, I think.

Assuming you find nothing off in the DACs reference, your most likely
suspects would be

- U2521, a 4051 analog MUX.
These have been known to fail sometimes. The way to check is to probe
pin 3 and pin 13 at the same time. You should see a repeating waveform at
pin 3, and on pin 13 you should see one of the values from that waveform
held at DC. If the switch is leaky, you'll see the input waveform bleed
through it.
- A leaky C2321 or C2322.
You'll see droop in the DC value on pin 13 of U2521 and/or pin 12 of
U2420(D) that's periodic with the refresh rate of the voltage (I think I
remember 15ms period, but don't quote me on that).

If none of those are the culprit, then either U2420 is bad or struggling
because something is loading down the -1.25V. Let's eliminate the lot above
first, but on my 2467, VR2420 had gone short, and was pinning the -1.25V
reference to ground. This lead to no trace and a bunch of other symptoms
that led me around the merry go-around for a while :).


Re: 7704 issues

Harvey White
 

On 29 Aug 2017 05:45:21 +0000, you wrote:

These harmonica connectors plug into a dual in-line connector which is numbered 1-60. They were all unplugged and in disarray when I opened the scope up. None of the lights light up on the vertical and horizontal mode selector switches or the left right switches.
It's possible that someone tried to diagnose a short in the frame by
removing all the connectors. I'd check the supply voltages before I
close it up.

Harvey



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