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Although not 100% accurate schematics for the TDS400 series have been posted to the files section of this group as well as TekWiki. They were scanned from "C" and "D" size engineering drawings and then converted mostly to "A" legal size. These were late pre-production drawings and did not contain the power supply (not Tek made). I did not have access to final engineering drawings. No manual was ever published by Tektronix for the TDS400 series which contained schematics or parts layout drawings or pictures. Being the first all digital oscilloscope which relied extensively on microprocessor control, it was new territory. The next series, TDS500, had manuals which were similar to past Tek manuals complete with schematics, theory of operation, and pictures.

I have no background in manual writing or compiling, just a technical background working at Tektronix for about 30 years. I was able to obtain the drawings from one of the engineers who designed the TDS series, now passed on. I tried to post on TekWiki but was not savvy enough to figure out the posting process.

I had sent a couple of the trigger related schematics to Tim Wright who was having triggering issues with his TDS420 in hopes it would help him find his problem. I then posted all my jpg files to the cloud and informed Tim that they were available for him to use. Kurt Rosenfeld at TekWiki has also been informed of the existence of the schematics.

Both Tim and Kurt have assembled my jpg images into a single pdf file. I thank them both for doing something that I had been unable to do which resulted in my work to be available to those who may need it. The TekWiki availability is here:
- or:


The schematics are available in the Group files section here:
/g/TekScopes/files/Tektronix%20TDS420_460%20Schematics.pdf

Best regards,

Ferrous Steinka

On Fri, Jan 17, 2025 at 06:41 PM, Sigur?ur ?sgeirsson wrote:

I really should look at doing the transient calibration on my 2467 now as
my GAS (Gear Acquisition Syndrome) has left me in possession of both a
home-made tunnel diode generator and e.g. an S52.

(Home made) tunnel diode generators obviously need very careful physical layout with minimal dimensions and preferably, checking and adjusting with a fast (sampling) 'scope.
In my experience, S-52's obviously have a fast (spec. is 25ps max.) rising edge but not such very nice flat behavior immediately after it: Spec. is -7%,+7% with max 10%pp within the first 1.8ns after the step. For its purpose (TDR), where only the edge speed counts, this was irrelevant. Leo Bodnar's pulser, which as I just found out is no longer being produced BTW, shows about -3%, +3% under/overshoot.
When putting my first TD pulser together, I was lucky enough to have S-2, S-4 and S-6 sampling heads in a Series 7000 Tek mainframe at my disposal. They mostly agreed and after quite some tweaking, the signal ended up being pretty fast (< 200ps) and flat. I'm talking about mm-size tweaks to get there.

I think for many here the journey is the reward.

It certainly has been for me, which is a wonderful thing when acquiring dozens of 'scopes.

Raymond
Raymond

On Fri, Jan 17, 2025 at 9:44?AM Jean-Paul via groups.io <jonpaul=
[email protected]> wrote:

Transient and CTT are most critical CAL, but PS,Hor and Vert are easily
done and more important.

I really should look at doing the transient calibration on my 2467 now as
my GAS (Gear Acquisition Syndrome) has left me in possession of both a
home-made tunnel diode generator and e.g. an S52.

You can CAL without the Tek CAL, but it is long and doubtful of complete
success.

I think first-time calibration from the instructions in the manual is
always going to be a long and doubtful process :). I know I had to run
through the process at least twice, and I probably repressed a couple of
run-throughs. I remember the B time base requires a second scope, and it
wasn't until years later and I'd scoured the schematics that I understood
the purpose of the step (for 15 minutes, don't ask me now).
I think for many here the journey is the reward, and at least OP is certain
to learn some things.

I should also note that the calibrator in the 2465-series is intended to
allow checking most of the time base calibration with nothing but the scope
and a 10X probe, that's why its output frequency follows the time base (to
a point).
The output of the calibrator is also specified to be 0.4V peak-to-peak to
sufficient accuracy to allow checking at least a couple of vertical ranges.

If you have CTT option the cal requires a precise 50% DC precise frequency and level.

If no CTT option ignore

Jon

On Fri, Jan 17, 2025 at 04:23 PM, Raymond Domp Frank wrote:

Are you using your 'scope to light the room? Why else would you use such high
intensity? None of my (40+) analog Tek 'scopes fully keeps focus at between 75
en 100% CW of Intensity. You say you have to readjust, so you can get it back
into focus, not that the trace totally loses focus. That makes it unlikely
that your CRT is fatigued (i.e. old, dying).

I guess more detail is needed.

Re-reading your message: Are you saying that when you need to use a high Intensity setting to achieve reasonable trace brightness because of low trace duty cycle/fastest hor. speeds, readout loses some focus? That's another matter and adjustment of (high intensity) focus should be optimized.

Raymond

On Thu, Jan 16, 2025 at 11:03 PM, vk2bea wrote:

My 2465B suffers from a miss-tracking of focus with intensity.
When the intensity is turned up (75 to 100%) I have to re-adjust focus. When I
do this the readout is out of focus (because it is a lower intensity).

Are you using your 'scope to light the room? Why else would you use such high intensity? None of my (40+) analog Tek 'scopes fully keeps focus at between 75 en 100% CW of Intensity. You say you have to readjust, so you can get it back into focus, not that the trace totally loses focus. That makes it unlikely that your CRT is fatigued (i.e. old, dying).

I guess more detail is needed.

Raymond

Hi! I have an old Fluke 105B Scopmeter Series II. I have its serial cable, but I have the chance to access its floppy disk with the FlukeView app. Is there anybody who can help me with the app or a compatible one?

Thank you!

I wonder if a Leo Bodnar pulse generator would work. IIRC, it can produce
pulses with 350 ps rise times.

DaveD
KC0WJN


On Fri, Jan 17, 2025 at 08:42 Sigur?ur ?sgeirsson via groups.io <siggi=
[email protected]> wrote:

Hey Keith,

I calibrated the CRT, timing, vertical and the triggers on my 2467 using a
TG501 and a PG506. I didn't touch the transient response calibration, but I
don't think the PG506 is fast enough for that. You need a much faster edge,
and IIRC Tek specifies a tunnel diode pulser.

I think if you have a decent signal generator or ARB, it should be able to
produce all the signals the calibration calls for^W^Wneeds. The horizontal
(timing) calibration is all done by eye, using the technician as a visual
comparator. TG501 is very convenient, as it gives you fairly narrow,
fast-rising pulses for timing marks and it's quick and easy to toggle to
the requested settings.
A square wave of the required frequency would work, though, even a sine at
a pinch. There'd be an awful lot of faffing about with controls, though :).

The vertical calibration is similar to the horizontal, e.g. the technician
is used to adjust levels until traces line up. IIRC you need a max of a 5V
peak to peak (ground to peak) signal for the vertical calibration, which is
easily done with a digital signal generator or an ARB that has 12bit
resolution or better. At the lower end it might be getting hairier, I don't
remember offhand what the signal levels are there, but to get good
resolution and low noise you might need to use attenuators, depending on
how your siggen/ARB works.
The trigger calibration is however automated, and is somewhat picky on the
signal provided, but again nothing you wouldn't be able to provide with an
ARB or a digital siggen.

Siggi

On Fri, Jan 17, 2025 at 7:00?AM Keith via groups.io <keith=
[email protected]> wrote:

Thanks Raymond, yes the fast edge rate is a problem, the 8112 is about

5nS

min.

However... I do have the Tek fast pulse PCB that is used in a PG506, I
believe that has < 1nS edges and could be driven by the 8112 to address

the

edge rate?

Also have access to a siglent SDG6052X which is a 500MHz function
generator.

Each Cal group is self contained, as long as it completes with no errors, the CAL for that procedure is saved to NV Ram.

Transient and CTT are most critical CAL, but PS,Hor and Vert are easily done and more important.

We use the original Tek cal, and the LeoBodnar for transient trim.

You can CAL without the Tek CAL, but it is long and doubtful of complete success.

Note that NV Ram defaults are available

Suggest you repost on tekscopes2, as our 2465B maven Chuck H was banned here.

Chuck may have more precise information.

Amicalement

Jon

This is all necessary as the original DS1225 had parity errors (it was datecode '96). I don't know of anyone locally who has the right Tek test gear so it's either try with what I have or leave the scope uncalibrated.

I could buy one of the Leo Bodnar fast pulse generators but they cost more than I paid for this scope!

- Keith

Hi Keith,
I saw Siggi's reply just after I sent mine.
He has a lot of experience with 2465 'scopes and always makes a lot of sense in what he says.

As an example, he may well be right re. transient response adjustment: After NVRAM replacement you don't need to do it, only after repair, exchanging parts or bending leads like those to the CRT. I don't know why you want to calibrate your 'scope, just assumed "full calibration".

Although horizontal (timing) employs verification by eye, you do need enough time resolution to be able to do that. A highest-resolution 2ns is used, right at the end of the Siglent's range of *sine wave* signals. The Siglent's square wave/pulse ranges end at 120/150MHz. Note 2465B SM 070-6863-01, Table 5-3, starting at point 28. Some adjustments only apply to some S/N ranges, see SM.

Vertical: I didn't check if your synthesised generators provide enough accuracy. The Siglent does provide enough resolution but I couldn't immediately find anything about its accuracy, except for DC.

The HP 8112A is analog, except for its controls. It is useless for anything that needs accuracy.

Raymond

On Fri, Jan 17, 2025 at 12:59 PM, Keith wrote:

However... I do have the Tek fast pulse PCB that is used in a PG506, I believe
that has < 1nS edges and could be driven by the 8112 to address the edge rate?

Also have access to a siglent SDG6052X which is a 500MHz function generator.

Keith,
The fast output stage of the PG506 has been / is to be adjusted while *in* a PG506. Because of the speeds (high frequency signal components) involved, its wave shape will be different if outside that PG506. So, you'll need to verify/calibrate it (!) before using it to adjust a 2465B. If you adjust without knowing its exact wave shape (which should be as square and flat as possible), you're adjusting the *combination* of the PG506's output stage as-is with the 2465B, which of course is of very little use. I don't believe you'll get even close and you might end up with significant adjusted-in over- or undershoot in your 2465B. And I left out the fact that a PG506 isn't really fast enough; you need something like the tunnel diode pulser as proposed in the 2465B's service manual. A well-tuned PG506 with known exact wave shape may do for "reduced requirements" though for rise time adjustment.
In case you'd consider a "Jim Williams pulser" or the like, which some people propose or use and which is easy to build, remember that the edge you need is a *step* i.e. a signal that contains relatively low frequencies (the flat parts, both *immediately* before and *immediately* after the step), to high frequencies (the steep range in between and its beginning and end). In effect, with a bare JWP you see (and adjust) a *slew rate*, not a *step time*, so *not* the correct frequency behaviour of your 2465B. "Rise time measurements" and adjustments using a JWP in most combinations of 'scope and pulser make no sense, even if some serious Youtube publishers try and make you believe otherwise.
You may consider purchasing a Leo Bodnar pulser for adjusting the step behaviour.

For the faster timing adjustments, the Siglent SDG6052X isn't fast enough.

For vertical sensitivity adjustment, you need a low frequency (1 kHz square wave or so) source with good amplitude accuracy (at the very least 2%). I don't think any of the instruments you mentioned have that, as far as specified, although there are (rather complicated) ways to correct for it.

Adjusting a 2465B is rather complicated and involved, especially first time. Add to that that the instrument is rather picky with regard to following the prescribed procedure (completely) and you'll realise that not using convenient instrumentation may be quite an uphill battle.

I trust you have replaced the NVRAM or you're sure it has enough life left? Your calibration results are stored there. I assume this whole exercise has become necessary as a result of NVRAM replacement.

You may be lucky in finding a TekScopes member close enough to you who may be willing to lend out his/her PG506/TG501/SG504 set...

Raymond

Hey Keith,

I calibrated the CRT, timing, vertical and the triggers on my 2467 using a
TG501 and a PG506. I didn't touch the transient response calibration, but I
don't think the PG506 is fast enough for that. You need a much faster edge,
and IIRC Tek specifies a tunnel diode pulser.

I think if you have a decent signal generator or ARB, it should be able to
produce all the signals the calibration calls for^W^Wneeds. The horizontal
(timing) calibration is all done by eye, using the technician as a visual
comparator. TG501 is very convenient, as it gives you fairly narrow,
fast-rising pulses for timing marks and it's quick and easy to toggle to
the requested settings.
A square wave of the required frequency would work, though, even a sine at
a pinch. There'd be an awful lot of faffing about with controls, though :).

The vertical calibration is similar to the horizontal, e.g. the technician
is used to adjust levels until traces line up. IIRC you need a max of a 5V
peak to peak (ground to peak) signal for the vertical calibration, which is
easily done with a digital signal generator or an ARB that has 12bit
resolution or better. At the lower end it might be getting hairier, I don't
remember offhand what the signal levels are there, but to get good
resolution and low noise you might need to use attenuators, depending on
how your siggen/ARB works.
The trigger calibration is however automated, and is somewhat picky on the
signal provided, but again nothing you wouldn't be able to provide with an
ARB or a digital siggen.

Siggi

On Fri, Jan 17, 2025 at 7:00?AM Keith via groups.io <keith=
[email protected]> wrote:

Thanks Raymond, yes the fast edge rate is a problem, the 8112 is about 5nS
min.

However... I do have the Tek fast pulse PCB that is used in a PG506, I
believe that has < 1nS edges and could be driven by the 8112 to address the
edge rate?

Also have access to a siglent SDG6052X which is a 500MHz function
generator.

Thanks Raymond, yes the fast edge rate is a problem, the 8112 is about 5nS min.

However... I do have the Tek fast pulse PCB that is used in a PG506, I believe that has < 1nS edges and could be driven by the 8112 to address the edge rate?

Also have access to a siglent SDG6052X which is a 500MHz function generator.

I’d be *very* surprised: You need a relatively low frequency (1MHz or so) square wave with an edge speed << 1ns for risetime/BW check and adjustment and low-and high-frequency pulses (up to 1GHz) for horizontal timing with an accuracy much better than the 2465’s spec, for starters.
The instruments you mention can’t do that, unfortunately.

Raymond

Has anyone managed to calibrate a 2465B without using the Tek specific test gear (PG506, TG501)?
I have an HP8112A pulse generator and an HP33120 function generator, can they be used instead?

- Keith

thanks for this - I will give it a serious try using the suggested plugins

--
Christopher Hilton-Johnson
The Stone Barn
Cottisford
Oxfordshire
NN13 5SW

07831 458867

Check power supply's for voltage and ripple first.

Then follow Z axis schematic and troubleshooting

Jon

Check out power supply, CRT, HV cal procedure first.

Likely failing caps or HV resistors

Jon

Hi All,

I have been working on a 2782 unit with questionable freq. and amplitude correction data making the unit not usable at the moment.

I have managed to get a working extension and serial IO card that gives me full keyboard service command control and feedback via trace mode, this allows me to look and store via screen dumps all correction data, good or bad.

I am reluctant to take the next step using time consuming manual commands and measurement setup to try to align FM narrow/freq. and amplitude correction data.

Does anyone have any prior knowledge or has worked on a 2782/4 in a past life?

My next step is to work through the manual Cal process and document all steps and what I have achieved along with all data/sw.

Now that I have a serial card and extender card working 100%, I may produce a bunch of extender cards with integrated serial interface to be made available if there is interest.

Any feedback is welcome.

Kind regards

Gerald
VK3GM