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On 2018-04-02 7:37 PM, snapdiode via Groups.Io wrote:

Thanks. I tried some typeface detection websites but even they couldn't come up with anything. It looks like the model numbers are in a different typeface?

Yes, they are set separately, and apparently in a slightly inconsistent
set of faces (since they're all done at different times).

All simple to draw, or so I thought. I used calipers on the spines and

tried to reproduce the letters with Open Office Draw, but it's a
terrible tool to play with.


It's all a question of how close you want it. I'd be happy to help
redraw the TEKTRONIX INC characters in say Illustrator -- but after all
that effort you'd still be stuck for model number setting.

I think I could find a commercial $$ font that is fairly close, but I
assume you'd prefer a free font? That narrows it down a lot -- and few
free fonts are very high quality. However I did find this free font:


Of course it's not exactly the same, but it looks quite attractive, and
I'd argue it's probably close enough.

--Toby

I'll try CAD tools next. Ideally I'd like a tool where I have separate X and Y scaling, so I can compensate for any printing discrepancies.

I can try drawing the letters as an RF trace in Allegro, I have precise control over widths and bends. But the K has a slight curve.

I've always wondered how this was printed back in the day. Some other manuals look like it was hot-stamped into the plastic.

Now that I look closer at the Tektronix manual, it looks like it could be a full size decal. That's what I'm trying, I bought some laser printer decal sheets and going to give it a try.

I was not clear in my original post. For the past year the museum board has
been evaluating the best way to make their invaluable collection of
microfiche available to Tek collectors. This microfiche collection has the
potential to become the most comprehensive and valuable archive we have to
support our interests.



It was the board's conclusion, having already investigated or tried
everything (and more) that our members have suggested, that the only
possible way to make the microfiche available was through a YouCaring
Fundraiser.



They are asking for your financial help reaching their goal of $6,000. It
isn't hard to understand how unlocking the information contained in the
museum's microfiche is in our own self-interest.



I just made a $50 donation towards the microfiche scanner. I hope you will
consider making a donation as well. The process is simple, you can pay by
credit card, and your donation is tax deductible. The donation link is:





Finally, the museum could do much more if they had additional volunteers who
are able to work at the museum. They have a long list of projects and an
acute shortage of volunteer manpower. If there is any way you can volunteer
please contact the museum at contactus@...
<mailto:contactus@...> .

Dennis Tillman W7PF

TekScopes Moderator and Co-Owner



---



The vintageTEK museum has an extensive microfiche collection and has
launched a YouCaring fundraiser to help purchase a microfiche scanner to be
able to digitize portions of the collection. Tektronix for decades released
documentation to the field on microfiche. While some of this information has
been made public, we know specific documentation was only released on
microfiche.



Today the museum can view the information but is unable to digitize it to be
able to support restorations, research, and customer inquiries. Please
contribute to the museum fundraiser campaign. Any amount is appreciated.



The museum operates solely by the support of volunteers, contributions, and
modest ebay sales. The museum does not charge for tours or special events so
your contributions are essential. vintageTEK is a 501(c)(3) charity so all
donations are 100% tax deductible under section 170 of the IRS code.



Please see our blog at

<>
for more
information or visit our YouCaring fundraiser site at
<>
www.youcaring.com/Vintagetek-fiche

< <>
>



Thank you for your support and contribution.



vintageTEK

On Mon, Apr 2, 2018 at 04:16 pm, Reed Dickinson wrote:

If resonance cannot be achieved at about 21KHz

It would be nice to able to really drive it at that frequency. My idea should work though. Part of the thing is to get enough voltage up to see if the CRT is shorted.

On Mon, Apr 2, 2018 at 03:29 am, John Brown wrote:

So there may (probably?) be other issues.

You can almost bet on it. I detest that type of power supply when it is self oscillating, but they are efficient when they work.

So either the transistors are underdriven or overloaded. There is no snubber capacitance to be at fault, the circuit really doesn't have an inductive kick like single ended ones.

If it proves to be the drive, hope it is C 1841/1834 or the resistors across them. In fact they warrant a quick check before going to other trouble. And the load on CR 1832/1833, or the diodes themselves.

(one of my JURB techniques if not)

I would find an audio amp and feed T 1960 with it. Whichever winding you choose to backfeed depends on the power of the amp. About a 3 KHz square wave should drive it well enough and probably won't destroy the amp. If you can't drive it to the full voltages they should at least be proportionately low. Watch that amp for heat buildup, they are not made for 3 KHz square waves, if current doesn't get it dv/dt could.

If you get proportional outputs from that side of the PS look at the drive. There isn't much to slow it down. (take that both ways :-)

I see the thing has current limiting but sometimes they sit there too long running into a short and go poof, maybe from heat if nothing else.

I see it senses beam current, HV current and the cathode of the CRT, but that isn't necessarily used for protection. I didn't read the theory of operation, if you can find the right section it might be worth a look.

I have original (bound paper) Tek Common Design Catalogs

#1 (October 1982): Semiconductors (includes Integrated Circuits)

#2 (June 1983): Mechanical



I am looking for Volumes 5 and 6

#5: Resistors and capacitors

#6: Wire, Insulation, Power Supplies



If anyone is interested in a trade please contact me off list at dennis at
ridesoft dot com

Dennis Tillman W7PF

Hi, I m from Argentina. I m repairing a 2445B. When I turn on it, the panel control lamps flashing one time only. The TRC never drawing anything.
I check the J119 voltages, for example....pin # 1. (-15V) I read -14,6V (+/- 0.2V) pin #8 I read 82V (+/- 0.3V) etc etc etc. The readouts are nearby but are not exactly.

Any suggestions?

Thanks.-

Thanks. I tried some typeface detection websites but even they couldn't come up with anything. It looks like the model numbers are in a different typeface?

All simple to draw, or so I thought. I used calipers on the spines and tried to reproduce the letters with Open Office Draw, but it's a terrible tool to play with.

I'll try CAD tools next. Ideally I'd like a tool where I have separate X and Y scaling, so I can compensate for any printing discrepancies.

I can try drawing the letters as an RF trace in Allegro, I have precise control over widths and bends. But the K has a slight curve.

I've always wondered how this was printed back in the day. Some other manuals look like it was hot-stamped into the plastic.

Now that I look closer at the Tektronix manual, it looks like it could be a full size decal. That's what I'm trying, I bought some laser printer decal sheets and going to give it a try.

Hi John:

My Tek Common Design Parts Catalog shows the Jedec part number as 2N6308. There are probably NTE replacements for the 2N6308. You should also replace all the associated diodes around the switching transistors with 1N4007 ones. They are rated 1KV at 1A, an overkill but a big safety margin. With an oscillator at about 21KHz test the resonant circuit components L1835 and C1835, they should display minimum impedance at resonance. Unsolder the anode end of CR1848 and go between TP1835 and pin 2 of P1960 to make this test. If resonance cannot be achieved at about 21KHz then one component of the resonant circuit is defective and a severe impedance mismatch exists between the power inverter circuit and T1960.

Reed Dickinson

I got a 7B53A in decent conditions. It seems in a good working state with one exception: the (broken) slider that selects "mixed mode" in delayed sweep, it's actuated by pulling the little red knob coaxial with the time-base knob.

I've posted three photos showing the case : /g/TekScopes/album?id=42160

Does anyone know where to find a possible replacement? Discarding the hypothesis of finding another 7B53A as a donor?
I'm thinking (as an extreme case) to install a miniature lever switch on the front of the plugin (making an appropriate hole) and wire it to the pcb pads after removing the old slider piece ...
Any suggestion is welcome.
Max

Hello,

This email message is a notification to let you know that a file has been uploaded to the Files area of the [email protected] group.

File: TEK Part Number System.pdf

Uploaded By: Robert Hay

Description:
Tektronix Part Number alphabetical and numerical reference (1984)

You can access this file at the URL:
/g/TekScopes/files/TEK%20Part%20Number%20System.pdf

Cheers,
The Groups.io Team

I have requested that Groups.io provide a search capability for the photo
albums.



This seems like a simple request since the albums are already in
alphabetical order and since they already provide search capability for many
other things.



Dennis Tillman W7PF

TekScopes Moderator

Albert,
Thanks for the heads up... my remarks just after your quote.

On Fri, Mar 30, 2018 at 01:12 pm, Albert Otten wrote:

Fabio, 151-0271-00 is not a matched pair, so Tek didn't judge that necessary .
20 mV difference is not important at all since these transistors are current
driven at the emitter. The transistors in the previous pair Q2405/2505 have
(or should have) enough headroom in Vce (maybe check this). This also explains
that you see no difference in collector signal. Difference in hfe could do
more harm perhaps, though I also doubt this.
A suitable replacement would be 2N4261. Sphere has a few new in stock under
151-0434-00, $6 each. In the cross ref also listed as 151-0271-00.

As you will see on my other reply to Roger, I managed to make the proper vertical LF step response right, by using the LF adjustments there are on the vertical plugin.
Those transistors though, seem to have become less important (but opportunely, I will try to find a replacement).
I also found, on the Tek semiconductor x-ref, that there seem to be a difference between the part 151-0271-00 and the 151-0434-00.
While the latter is indeed a direct equivalent to the 2N4261, it seems the 151-0271-00 is a variation of the 4261, which they called the A5T-4261.
The a5T kind is an 80mA Ic part, while the vanilla 2n4261 is a 30mA part.
The A5T has a TO-92 package and seems also to be capable of dissipating more power as well (0.5W against 0.2W the TO-72A package of the 2n4261).

Krgrds,

Fabio

I set this on top during extended run time periods. /g/TekScopes/photo/37195/10?p=Name,,,20,1,0,0

Hi Bob,
I had no idea it was in there. It is in my 1982 Materials Catalog as well. It is buried in there between different materials where I would never have found it if you hadn't mentioned it.

When you upload the lists be sure to send a copy to Kurt at TekWiki so he can put it up there.

Dennis Tillman W7PF

This is a Permanent Split Capacitor motor. The cap, which is used all the time, not just for starting, causes a phase shift in its associated winding, which makes part of the overall magnetic field appear to rotate instead of just vibrating back and forth. Shaded-Pole motors do the same thing, less efficiently, with a shorted turn around part of the pole pieces.

I can see two uses for a fourth wire. It could be safety ground, or there could be two wires - possibly a separate winding - for the cap instead of one tap and one end. If you have a wire too short to reach, I guess it's moot.

I too was upset by the noise of my (three-wire) fan, and after bearing replacement which made no difference, and cushion-mounting which didn't make enough difference to satisfy, I retrofitted a computer tubeaxial fan, which is less obnoxious and moves more air. I love it. I posted my experience in "453 fan bearings", and pictures in "453-454 Tubeaxial Fan Retrofit" at /g/TekScopes/album?id=12878.

Regards,
Dave Wise
________________________________________
From: [email protected] <[email protected]> on behalf of Phillip Potter <p.potter@...>
Sent: Friday, March 30, 2018 6:17 PM
To: [email protected]
Subject: [TekScopes] 453 scope fan wiring help needed!

Hi all,

The fan on my scope was very noisy, so I pulled the back apart and got
the fan apart from the shroud, only to find that the wiring is soldered
in with no way to get the fan out to work on it. So.... I cut the
wires. Now, in the process of returning it to the scope, I've been
reconnecting the wires, BUT in my clumsy style I managed to pull the
shortest of the four (the black one) out of the back while attempting to
strip it! Grrrr.

So, now I can't tell where the wire connects to the scope! I have three
different schematics (manuals) and NONE of the three show a fan with
FOUR wires!!! Only three...... What the heck?!?

Is there anyone here who can shed some light on what I should do now?
That is... after I shoot myself!

Thanks in advance for anything you can suggest.

Phil

Hello Roger,
Apologies for the long delay for feedback... I was getting my hands dirty on the thing.
See my comments right after yours...

I have just checked on my 7A26 and the Low Frequency Compensation (attenuator)
adjustments do have about the correct time constant to correct for your 3usec
lag in response (I only checked one of the attenuator settings, 0.1V and
C114,C115). You could try using the 7A26 LF compensation to flatten the 1 -
3usec region before going back to the mainframe adjustments for the higher
frequency components. I am sure you can see why the standardizer plugin is
useful - you have HF compensation both in the mainframe and the plugins.

I confess that when I read your message, my first reaction was to dismiss your suggestion, because you meant adjusting the input attenuator, and since I am using - on purpose - a 25mVpp signal, I am using the 5mV/div range, which doesn't engage any attenuator that I could compensate for.
But, your message did trigger my curiosity about what could possibly be the AC frequency compensation adjustments on the plugin and - bingo - besides the attenuators (which were ruled out), the 7A26 has not one, but two LF response adjustments, R1436+C1436 with average time constant of 150us, and R1431+C1431 with avearge time constant of 5.5us.
And not surprisingly, those 2 adjustments together, in combination with the lowest frequency response adjustment of the MF's vertical amplifier, have plenty of room for correcting the low / mid frequency lacking that I was finding.

I think the sharp 'knee' you have shown on the YT video is due to trying to
correct the low frequency error in the plugin with the HF adjustments in the
mainframe. Adjusting the lowest frequency / latest time errors first reduces
the interaction between the adjustments.

Yes, I always try to go from LF to HF, but I was kind of blinded by the fact that the signal I was seeing (at the plugin's output) was free of that LF lacking, so I was convinced that I had to pursue the solution at the MF's amplifier alone.
But the bottom line is, I don't have experience enough with the 7000 family to know what would be a correctly looking signal at the plugin's output, never mention that my test rig was less than ideal in this case, looking at only one side of the balanced output, with a long ground lead... my assessment of the "correct" signal coming out of the plugin was, at least, subjective.

I hope I am helping rather than adding confusion, best wishes,

Not at all, your suggestion pointed me in the right direction and I managed to get the overall vertical step response well adjusted.
I`m not getting (yet) a step response as fast as I managed to get from my 464 of 3.5ns... I can only get to 4ns, but I may still be getting confused about the great number of adjustments there are (between the MF and the Vertical plugin), and the almost infinite possible combinations...
But I`m happy for now... Good enough for government's work!

There are a few other issues that are bugging me (on the horizontal axis... an intermittent jitter), and I will pursue that first, before trying to perfect the vertical any further... but that's subject for another post.

Rgrds,
FT

Thanks for that, pretty cool. My two 754's were originally delivered to Texas Instruments and Virginia PolyTech University. The newer one was delivered in April '99 -? it's a B032XXX. So looks like they delivered about 3,000 units per year at the end.
--Eric
Sent from my Samsung Galaxy S8.

On Mon, 2 Apr 2018 09:05:54 -0400, you wrote:

Chuck,

Thanks.? I figgered they were used for bending leads, I was just unsure
how one utilized those tools.? I've only used smooth needle nosed pliers
of different shapes to put the bend in the components using the TLAR
(That Looks About Right) method of measurement. Those look like handy
little tools to have around.

Slide the tool until the outside is just inside the holes for the part
on the board. Use that notch.

If you have the lead bending tool (the one with the thumbwheel), then
there are tips much like a caliper. Use them and you set the lead
spacing.

There's another tool that is somewhat a combination of the two, and it
sets leads and does an inwards crimp to elevate the part.

Harvey

Mark


On 04/02/2018 08:42 AM, Chuck Harris wrote:

They are used to bend the leads on an axial
part, that will lay down on the PCB, so that
they will fit the spacing of the holes in the
board.

You put the axial part in the middle of the
guide, with its leads in the lead slots for
the proper hole separation, and then push the
leads down to bend them at 90 degrees to the axis.

There are also pliers that can be adjusted for
width that perform the same function. I have
a pair with pointed tips that you turn a thumb
wheel until they fit in the board holes, and
the you stick the part in press the clamp trigger,
and bend the wires with your fingers.

I made another tool (back in the day) out of a
cheap pair of needle nosed pliers, that crimped
the resistor leads into a "U" to space them up
from the circuit board... but that is another
story.

-Chuck Harris

Mark Wendt wrote:

On 04/02/2018 03:34 AM, Michael A. Terrell wrote:

Velleman-VTBEND1-Resistor-and-Axial-Component-Lead-Bending-Tool-Set

These are the tools that were in common use when that scope was built. You might
find them cheaper somewhere else, but they are worth the asking price. I've had
mine for about 30 years.

Michael A. Terrell

Never having used something like those, how exactly do you use them?

Mark

I've always (50+ years) used one of these:



They no longer sell them but I'm sure others do. I got a bunch on closeout from Travers for 10 cents each!

Vince.

--
Michigan VHF Corp.

That page () is the work of Peter H, who is a very active editor of Tekwiki.



Thanks, Peter!

-Kurt