Date   
Re: Tek 465 external trigger input cap substitute?

 

I *think* you'll find that is C602 if it is the one that goes to ground from
the centre conductor of the BNC. According to the parts list that's a 2.7pF
(+/- 25pF) 200V ceramic cap. Is suspect they mean 2.7pF +/- 0.25pF ...

Good luck finding anything like that these days

Dave

-----Original Message-----
From: TekScopes@... [mailto:TekScopes@...]
Sent: 09 September 2017 11:13
To: TekScopes@...
Subject: [TekScopes] Tek 465 external trigger input cap substitute?

Hello there!

While removing the trigger board I have broken the "A trigger" external
input cap.
I'm pretty sure that the broken one was marked "500" and it's ceramic, but I
cannot find it on the manual.
In the schematic it seems to be the C601 with value 2.7.. (2.7 what, pico?)
but on the layout it's missing.
After watching some photos on the Internet it looks like mine was
substituted, since they look like a big resistor with a concentric hole.

Have you got any suggestion on what sort of cap should I replace it with?
Thank you very much!







------------------------------------
Posted by: marconikkor@...
------------------------------------


------------------------------------

Yahoo Groups Links

Re: Tek 465 external trigger input cap substitute?

Göran Krusell
 

Hi,
it is a bit difficult reading this schematic diagram. But C601 (0.1 uF, 100
V) is on the line trig input while
C602 (2.7 pF, 200 V) is on the A EXT trig input. C602 is not present on the
layout in my manual but is found in the component list. It has been added
on a later version but details have not been updated accordingly.
If you have it or not is not all that critical, it has some effect on probe
matching, I think.

Göran


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

Tek 465 external trigger input cap substitute?

Marco
 

Hello there!

While removing the trigger board I have broken the "A trigger" external input cap.
I'm pretty sure that the broken one was marked "500" and it's ceramic, but I cannot find it on the manual.
In the schematic it seems to be the C601 with value 2.7.. (2.7 what, pico?) but on the layout it's missing.
After watching some photos on the Internet it looks like mine was substituted, since they look like a big resistor with a concentric hole.

Have you got any suggestion on what sort of cap should I replace it with?
Thank you very much!

Re: How I made my 577 work without a HV transformer

 

Hi Chuck,

Which scope model had the plexiglass portals?

That was an interesting piece of history that I was not aware of. I never saw a Tek scope with that feature although when I got started in my first real electronics job, the lab I was in still had a few old 535 mainframes along with its newer 545s and 547s.

Walter's suggestion was quite general. I don't believe he was expecting me to do anything specific. In fact when I followed up with him after I looked at my 600 monitors and found they didn't have differential inputs he didn't make any more suggestions. Here is what he suggested.
"how about remoting the XY signal to another display?
I got through this a lot with HP specans that have bad
CRTs, mind you, they have XYZ outputs, but is it possible
to make these signals and just go to another display? lots
of Tek 600-series and hp 1340-series units to do this.".

His suggestion was a good one, and I didn't stop looking even when I found the 600 monitors were not going to work. I didn't actually think of connecting directly to the plates of a CRT although I can see why you would have considered that a real possibility since you were exposed to the scopes with the portals on the side. I should have thought of connecting directly to the plates (but I didn't) because I once connected the 7A21 to the plates of a 7904. That plugin is not technically not an amplifier at all since it is entirely passive. It connects the front panel input signal directly to the plates of the 7904. It was a way to get 1GHz performance out of a 7904 before the 7104 became available. It is unlike all other plugins inside. It is completely made up of hardline copper plumbing.

Dennis Tillman W7PF

-----Original Message-----
Sent: Friday, September 08, 2017 5:08 AM
Subject: Re: [TekScopes] How I made my 577 work without a HV transformer

Back in the days of yore, tektronix oscilloscopes had plexiglass portals on the side of the case that allowed access to the CRT's deflection plates. The idea being that if you needed to display something that exceeded the capabilities of the scope, you had a nice little CRT there that was all biased up and ready to go... you could simply hook directly to the plates, and display what you needed to display. The plexiglass even was split into two halves, and had 4 little divots at the split to hold the wires separated.

What Walter was probably expecting you to do, was to disconnect the deflection plates on your 600 monitor, and clip lead the deflection amplifiers from your 577 to the plates on the 600, and let it display.

-Chuck Harris

'Dennis Tillman' @Dennis_Tillman_W7PF [TekScopes] wrote:
Necessity is the mother of invention. I needed to measure some
transistors but the HV transformer on my 577 was dead so there was no
CRT beam and thus, no display.

Walter Shawlee suggested I try connecting the horiz and vert output
signals from the 577 temporarily to one of the 600 monitors so I could
start testing until the replacement HV transformer arrives. The 577
horizontal and vertical signals are differential so I needed to have
differential inputs for each axis. I have a few of these 600 series
monitors but none have differential inputs (that was an extra cost
option and, apparently, not very common).
------------------------------------
Posted by: Chuck Harris <cfharris@...>
------------------------------------

Re: How I made my 577 work without a HV transformer

Roger Evans
 

I used the single ended approach that David suggested when I was checking out a 2221 with an obviously broken CRT (broken glass in the case) several months ago. I could see that the analogue side was largely OK from the waveforms on the X and Y plates but I wanted to confirm the digital side was functioning, particularly since I couldn't find schenatics for the digital boards of my model ( a non-A series with the 100MHz bandwidth). I happened to use a 485 in XY mode with no Z signal and it worked well enough to check the digital side, read the on-screen displays and even to confirm the rise time of the Y circuitry. I then managed to unravel the mysteries of the GPIB interface and it was almost an anti climax when I finally got a replacement CRT.

Regards,

Roger

Re: 465M Power Supply Problems

n4buq
 

I figured I'd pay for that comment... :)

The programming I do just doesn't have requirements to be particularly compact or particularly fast. We have some [usually] vague requirements regarding response times, but nothing that's critical like there would be for applications such as missile guidance systems, etc. Our bigger concerns are network throughput, database response times, etc. moreso than processing time for the code we write.

Thread is going way off topic (and I'm as much to blame as anyone). Choke is scheduled to be here tomorrow and hopefully I can tie the ribbons on this thread.

Thanks,
Barry - N4BUQ

----- Original Message -----
From: "Mark wendt.mark@... [TekScopes]" <TekScopes@...>
To: TekScopes@...
Sent: Friday, September 8, 2017 5:23:51 AM
Subject: Re: [TekScopes] 465M Power Supply Problems

On 09/07/2017 10:24 PM, Barry n4buq@... [TekScopes] wrote:
Well, even if a bigger, more expensive ROM were required, each byte would
still cost the same as all the other bytes in it. :)

I get what you're saying, though. I'm glad I'm not generally constrained
like that the way some folks had/have to be. It seems it isn't important
anymore for most programming efforts these days - at least not the types
of programs I write.

Thanks,
Barry - N4BUQ
And that's how we end up with bloatware, like Microsoft Windows.

Mark

Re: How I made my 577 work without a HV transformer

Chuck Harris
 

Back in the days of yore, tektronix oscilloscopes had
plexiglass portals on the side of the case that allowed
access to the CRT's deflection plates. The idea being
that if you needed to display something that exceeded
the capabilities of the scope, you had a nice little
CRT there that was all biased up and ready to go... you
could simply hook directly to the plates, and display
what you needed to display. The plexiglass even was
split into two halves, and had 4 little divots at the
split to hold the wires separated.

What Walter was probably expecting you to do, was to
disconnect the deflection plates on your 600 monitor,
and clip lead the deflection amplifiers from your 577
to the plates on the 600, and let it display.

-Chuck Harris

'Dennis Tillman' @Dennis_Tillman_W7PF [TekScopes] wrote:

Necessity is the mother of invention. I needed to measure some transistors
but the HV transformer on my 577 was dead so there was no CRT beam and thus,
no display.



Walter Shawlee suggested I try connecting the horiz and vert output signals
from the 577 temporarily to one of the 600 monitors so I could start testing
until the replacement HV transformer arrives. The 577 horizontal and
vertical signals are differential so I needed to have differential inputs
for each axis. I have a few of these 600 series monitors but none have
differential inputs (that was an extra cost option and, apparently, not very
common).

Re: 466 with no bright after 10 minutes!

hyl
 

i had a 464 with just exactly same behavior. pretty much it's hv transform problem. just gonna winding a new one. but ohhh. its hard way without replacement.

good luck.

Re: How I made my 577 work without a HV transformer

 

There is a good chance that accepting just half of each differential
signal into a singled ended plug-in would have also worked. It would
have resulted in a noisier display because the common mode noise would
have been added to just half of the signal but possibly not
noticeably.

On Thu, 7 Sep 2017 21:32:21 -0700, you wrote:

...

The 577 horizontal and
vertical signals are differential so I needed to have differential inputs
for each axis. I have a few of these 600 series monitors but none have
differential inputs (that was an extra cost option and, apparently, not very
common).

...

Re: 465M Power Supply Problems

Mark Wendt
 

On 09/07/2017 10:24 PM, Barry n4buq@... [TekScopes] wrote:
Well, even if a bigger, more expensive ROM were required, each byte would still cost the same as all the other bytes in it. :)

I get what you're saying, though. I'm glad I'm not generally constrained like that the way some folks had/have to be. It seems it isn't important anymore for most programming efforts these days - at least not the types of programs I write.

Thanks,
Barry - N4BUQ
And that's how we end up with bloatware, like Microsoft Windows.

Mark

Re: How I made my 577 work without a HV transformer

 

Hi Craig,
I am aware that there is such a list which was informally compiled by one of
the Tek engineers so it is probably not meant to be comprehensive.
Unfortunately I do not have access to this list.

Dennis Tillman W7PF

-----Original Message-----
Sent: Thursday, September 07, 2017 10:04 PM
Subject: RE: [TekScopes] How I made my 577 work without a HV transformer

A pair of 7A13 differential comparator plugins (designed by Bill DeVey
who also did the 1A5, 7B52 and 7b92 timebases, and the 81 Plug-In
Adaptor)
The whole account of how you got the 577 up and running sans transformer was
extremely interesting Denis.

But it was also fascinating who developed the 7A13 and what else he
developed.

Do you have a knowledge of who developed which instrument? I know that Bruce
Hofer (of Audio
Precision) was important in the development of the 7000 series, as was
Barrie Gilbert (readout system, and custom IC's using the Gilbert Cell), but
that is as far as my partial knowledge extends.

Craig
------------------------------------
Posted by: "Craig Sawyers" <c.sawyers@...>
------------------------------------

Re: Smallest Tek scope

Carlos
 

Hi Carlos,
Nope. I'm not that old. In 1960, I was
entering kindergarten.
The scope I remember seeing had cam switches,
and was solid state. Maybe 73 magazine?
-Chuck Harris
Chuck,
There's a 73 magazine searchable index here:

<https://mikeyancey.com/73mag/index.php>
but writing the words <oscilloscope> or <scope>  inthe title box only shows one scope construction projectin the 70s, in the November 1976 issue:
<https://archive.org/details/73-magazine-1976-11>
however that scope seems not to be small.
So no, it seems it was not 73 magazine.
I was studying electronics during the years 75-79, and the university'slibrary I attended had a wonderful collection of Electronics magazine,
the one which was published by McGraw-Hill. I remember each issue
was thick, full of interesting articles. Even the ads were great!.

Maybe you saw the scope in that magazine?
Carlos


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

Re: Smallest Tek scope

DON CRAMER
 

Thank you for the link!

Every time this Tek Nano scope subject comes up, I unsuccessfully try to find this magazine do-it-yourself project I vaguely remember as a young lad. And finally, here it is. Great stuff! :>)

Don

________________________________
From: TekScopes@... <TekScopes@...> on behalf of 'Michael A. Terrell' mike.terrell@... [TekScopes] <TekScopes@...>
Sent: Thursday, September 7, 2017 10:30 AM
To: TekScopes@...
Subject: Re: [TekScopes] Smallest Tek scope

1970? I was a senior in high school and I took that magazine into class to read, while my teacher bored the class with more of his meaningless stories. It was the January Electronics Illustrated, and there is a copy is on the site I linked to. I thought about building it but I decided that it was too crude, so I waited a year and bought a new Leader LBO505 dual trace scope.

Here is a link to a scan:

http://www.americanradiohistory.com/Archive-Electronics-Illustrated/Electronics-Illustrated-1970-01.pdf

I think that I still have my copy of the magazine, but I can't get to where it is stored right now.
...

Re: How I made my 577 work without a HV transformer

Craig Sawyers <c.sawyers@...>
 

A pair of 7A13 differential comparator plugins (designed by Bill DeVey
who also did the 1A5, 7B52 and 7b92 timebases, and the 81 Plug-In Adaptor)
The whole account of how you got the 577 up and running sans transformer was extremely interesting
Denis.

But it was also fascinating who developed the 7A13 and what else he developed.

Do you have a knowledge of who developed which instrument? I know that Bruce Hofer (of Audio
Precision) was important in the development of the 7000 series, as was Barrie Gilbert (readout
system, and custom IC's using the Gilbert Cell), but that is as far as my partial knowledge extends.

Craig

How I made my 577 work without a HV transformer

 

Necessity is the mother of invention. I needed to measure some transistors
but the HV transformer on my 577 was dead so there was no CRT beam and thus,
no display.



Walter Shawlee suggested I try connecting the horiz and vert output signals
from the 577 temporarily to one of the 600 monitors so I could start testing
until the replacement HV transformer arrives. The 577 horizontal and
vertical signals are differential so I needed to have differential inputs
for each axis. I have a few of these 600 series monitors but none have
differential inputs (that was an extra cost option and, apparently, not very
common).



Then it occurred to me that a 7603 with the right amplifiers might work just
as well as a 600 monitor. I needed to provide the capability for
differential inputs for each axis on the 7603 (or any 7000 scope mainframe)
for this to work. A pair of 7A13 differential comparator plugins (designed
by Bill DeVey who also did the 1A5, 7B52 and 7b92 timebases, and the 81
Plug-In Adaptor) would have the required differential inputs I needed and,
fortunately for me, I had two working ones. So I stuck one in the vertical
slot and one in the horizontal slot of a 7603. Then I made a nice cable
(from standard four wire telephone cable), to connect the two instruments
together.



It worked perfectly. Now the 7603 displays the transistor curves as if it
was the top half of my 577. Every control (except for brightness and focus)
on the 577 still works exactly as it used to. The only tiny discrepancy is
there is no blanking to dim the trace when it is just a dot in the corner,
also, the 577 has blanking at the end of each current step that is missing.
I suppose if I really wanted to I could have added a fifth wire to the cable
for the blanking signal but it really was not an issue.



Dennis Tillman W7PF

Re: 465M Power Supply Problems

n4buq
 

Well, even if a bigger, more expensive ROM were required, each byte would still cost the same as all the other bytes in it. :)

I get what you're saying, though. I'm glad I'm not generally constrained like that the way some folks had/have to be. It seems it isn't important anymore for most programming efforts these days - at least not the types of programs I write.

Thanks,
Barry - N4BUQ

----- Original Message -----
From: "edbreya@... [TekScopes]" <TekScopes@...>
To: TekScopes@...
Sent: Thursday, September 7, 2017 9:14:33 PM
Subject: Re: [TekScopes] 465M Power Supply Problems

Barry said:

"I'm a programmer. One byte costs the same as the other ones."

Not all bytes are the same cost. For example, one byte too many of code that
would cause you to need the next size up in ROM could be very expensive,
making it worthwhile to add effort to clean and reduce it to fit. There are
many instances like this in all fields of endeavor - the big decision points
are usually at the margins.

Ed



Re: 465M Power Supply Problems

Ed Breya
 

Barry said:

"I'm a programmer. One byte costs the same as the other ones."

Not all bytes are the same cost. For example, one byte too many of code that would cause you to need the next size up in ROM could be very expensive, making it worthwhile to add effort to clean and reduce it to fit. There are many instances like this in all fields of endeavor - the big decision points are usually at the margins.

Ed

Re: Smallest Tek scope

Michael A. Terrell
 

They ever caught me. Even in electronics class. :)

-----Original Message-----
From: "Barry n4buq@... [TekScopes]" <TekScopes@...>
Sent: Sep 7, 2017 2:06 PM
To: TekScopes@...
Subject: Re: [TekScopes] Smallest Tek scope

"Honest - I bought it for the articles!" (Page 21...)

Thanks,
Barry - N4BUQ

----- Original Message -----
From: "'Michael A. Terrell' mike.terrell@... [TekScopes]" <TekScopes@...>
To: TekScopes@...
Sent: Thursday, September 7, 2017 12:30:30 PM
Subject: Re: [TekScopes] Smallest Tek scope

1970? I was a senior in high school and I took that magazine into class to
read, while my teacher bored the class with more of his meaningless stories.
It was the January Electronics Illustrated, and there is a copy is on the
site I linked to. I thought about building it but I decided that it was too
crude, so I waited a year and bought a new Leader LBO505 dual trace scope.

Here is a link to a scan:

http://www.americanradiohistory.com/Archive-Electronics-Illustrated/Electronics-Illustrated-1970-01.pdf

I think that I still have my copy of the magazine, but I can't get to where
it is stored right now.

-----Original Message-----
From: "Chuck Harris cfharris@... [TekScopes]"
<TekScopes@...>
Sent: Sep 7, 2017 8:08 AM
To: TekScopes@...
Subject: Re: [TekScopes] Smallest Tek scope

Might not have been PE magazine, I did subscribe to them
for quite a while, though, before I got disgusted with them.

...Let's see, how long ago was 1970?... Best not think about
that!

-Chuck Harris

'Michael A. Terrell' mike.terrell@... [TekScopes] wrote:
-----Original Message-----

From: "Harvey White madyn@... [TekScopes]"
Sent: Sep 6, 2017 5:20 PM
To: TekScopes@...
Subject: Re: [TekScopes] Smallest Tek scope

On Tue, 5 Sep 2017 23:06:13 -0400, you wrote:

Back in the early 1970's, Popular Electronics magazine
did a construction article on making a scope with a 1"
diameter CRT. The construction techniques were pure
tektronix, as I remember... cam switches and everything.
Hmmm, I missed that one, but they did have a "min-o-scope" which used
a 1EP1. It needed 2 or 3 tubes 1 vertical, 1 sweep, and was as basic
as you could get. I put one together in a 5x7x2 box. I won't go with
how badly it was wired, but it did work.

The thing would easily fit in a coat pocket... about
the size of an instamatic camera. The NLS mini scope
came out somewhat later, and had a bigger CRT.
Hmmm, I don't remember that as a construction project.

Perhaps the engineer that did the scope you saw, wrote
up the design for Popular Electronics, when Tek spurned
his design?
Possible, but where to get the cam switches was another matter. The
CRT was not a cheap thing at that time, so this was one of their more
expensive projects. No transistors at all.

Maybe I'm thinking of something in the mid 60's and ignored the one in
the 70's, after I gave up on them.



Here is an archive of Popular Electronics magazines:
http://www.americanradiohistory.com/Popular-Electronics-Guide.htm

Michael A. Terrell

Michael A. Terrell

restore of 2x 2465, sharing what I found so far

satbeginner
 

Hi all,
last week I received two 2465's from eBay to restore.


Why? I just love the 2465's, I already have two 2465B's, so now I want to restore these back to perfect again.
I just like to restore these things, and then look on the web for all the missing parts, like blue screen, knobs, top-bags, angled power cables, etc.




Scope 1:
This one came from the USA, so I had to set the line voltage to 230V.
I opened the cabinet, and there were only a few small spiderwebs, so I decided to switch it on. (It was showing traces on eBay when it was for sale)
It sort of worked, the read-out was visible, but the traces were jittering a lot in horizontal direction.
After about ten minutes it ended all with magic smoke and a bang, and yes.... both RIFA's were gone :-)
From previous restores I still had a new pair of replacements, so that was a quick fix, also one of the 68 Ohm resistors needed replacement.


Now I started looking for the cause of the horizontal jitter (just the traces were moving, not the readout, so no U800 problem?!)
I cleaned contacts of U700, also swapped it with U900, but no improvement there.


I found information here in the group about the A sweep being controlled from the A5 board (A Tim Ref), and yes, I found the output of the quad OpAmp U2427B, a TL074 (pin 7) being the cause of this jitter.
The local reference voltages (1,25V and also the inputs of the opamp were solid as a rock, so it must be the opamp.
I replaced that one and: succes, traces were stables now!


I did find another problem: the ground switch of Ch-2 did not work.


I removed the input attenuator for Ch-2.
To do this I removed the front bezel, removed the right front panel, removed the little metal cover at the end of the attenuator and unsoldered the two thin connections with the A1 board.
Now I could remove two screws at the front of the attenuator and also two screws at the bottom of it. (This is the reason I had to remove the right half of the front panel.
Having the attenuator removed from the scope (beware of the very thin groups of plug-in pins at the bottom of the attenuator for the relay coils, handle with care)
I could remove the relay top half of the attenuator and clean both the gold plated contacts on the ceramic platter and the contact springs on the relay top half.
Putting things all back in reverse order showed it was all OK now.


It is clear it needs calibration, but basic testing showed that everything works now.




Scope 2:
This one is from the USA too, and was shown on eBay with a compressed screen, but both in horizontal and vertical direction. (For me a typical image with the beamfinder pressed..)
This one needed a lot more cleaning, and this time, before powering on, I did check the RIFA's, but they were already replaced, or at least another brand.


A quick check learned that indeed the beamfinder switch was stuck/dirty, so I cleaned it and a (almost) normal trace was shown.
It became clear that (maybe a previous repair attempt?) almost all the basic settings like focus, astig, grid bias, etc. were 'tested'.
I adjusted them as described in the calibration manual, and the image became quite sharp.


But, now also showing a single row of dots at the bottom of the screen.
As far as I could find, this is related to the scope not being calibrated, so I decided to perform a quick calibration to see if the dots would disappear.
Yes, they did, but... after about 6 minutes the would reappear.


Since this scope has a "through the board, non-smd) A5 controller with an ER1400 memory, my guess now is that this memory is "dead".
I am not familiar with the long term behaviour of this kind of technology, I hope the loosing of its data is related with the age and actually being used, and not just age only...?
Anyway, I ordered a NOS chip and when it arrives I will replace it to see if the calibration will stick.


When the scopes are both back in working order again, I will order the famous CAP list at Mouser, so I can recap both power supplies and calibrate them, so these scopes will be OK for a (maybe new user?) in the future.




To be continued,


Satbeginner (Leo)

Re: Smallest Tek scope

Ed Breya
 

This talk all made me take a stroll down memory lane. The very first scope I ever saw in person was when I was in 6th grade. It was some kind of show-and-tell event, and a kid brought in a home-made or kit form scope that his dad had built - it was probably from one of those home-study electronics courses that were so prevalent then. It had about a 2" CRT, all packaged up in classic 1940s style cabinet and knobs, etc. And it worked, set up to present a Lissajous. I was very impressed, although the other kids had no clue to its significance.

Back then there were all sorts of WWII surplus to make things from, and lots of people getting into electronics. I recall also the other extreme advertised in the magazines - "Make a Giant Oscilloscope from Your Old TV," or something like that for the headline. These would have had impressive screen size, but of course very limited bandwidth due to the magnetic deflection.

If anyone wants to seriously consider dabbling around in miniscope territory, an alternative to the old small CRTs is to use "modern" ones salvaged from equipment like camcorders of the 1970s-1980s. Tiny CRTs were used for the viewfinders, and were essentially complete miniature video monitors, with screens so small they needed a magnifier in front. Converting one from TV to scope use could be done just like in the old days. Again, the BW would be quite limited, but probably in the same range attainable with the old-school small electrostatic CRTs.

I have a few of these viewfinder CRTs that I keep in the curio cabinet, only due to cuteness - I have no practical use for them. One generation type has about 1" to 1.25" diagonal rectangular screen, and maybe 4-5" long. The smallest are 5/8" D round screens, by about 3" long.

Ed