开云体育

The rejuvenation seldom works long term.

Old TV boosters just raised the filament voltage a bit.

Suggest that you Look for 3RP1 CRT on eBay or ham flea market

Jon

I just got a Tek 468 from one of the guys here in town. It's missing the back cover and feet.

Does anyone have what I need to put my scope back together? Just the parts or an old junker would be great.

I have a photo, but I don't know how to attach it here.

Thanks!
Mike Harmon, WB0LDJ
mharmon at att dot net

This discussion of the physics of rejuvenation and double peaking here fascinates me! I'm about to try rejuvenating a 3RP1 CRT in my Heathkit HO-10 monitor scope (sorry, not a Tek scope, but hopefully still relevant to this forum). At the brightest setting, the cathode current is 0.5 uA. The trace line is very dim and also very thin, thinner than the line on various Tek 'scopes I have. It does not have double peaking. I don't know if rejuvenation has been attempted on it before. Are there any measurements I could do before, during, or after that could contribute to the discussion here?
Halden VE7UTS

Good evening Guys,
I released the new edition of my book about the 7000 Series, more than 800 pages completely rewritten.
It is still free and available from my web page (www.k100.biz).
Enjoy!
Gianni

Here is also a small video to present the new book published by Elektor about Tek restoration

Thanks for this - it will be much easier than the images emailed from my phone!
Ron

Good on ya!

Hi Clark,

Thank you for the advice and photos ... I have finally succeeded in getting the BNC nut undone ...

For anyone with same issue ... disconnected all the Front Panel switches, removed the Readout pcb, then removed the Front Panel with Cam roller switch intact. I then had sufficient space to use a 'modified' a 9/16inch open ended spanner similar to Clark's. All the Finger contacts are now easily accessible ... ie. Readout and two sets of Attenuator switches.

Maybe now I can troubleshoot the real issues ... :)

Thanks,

--
Cheers,
Ian,
Melbourne, Australia

Hi Ron,
I have a utility to print the screen to a file for the Tek THS7xx scopes. Source code for it is here: . Code is there for both Linux and MS

'73
Bob

Correction: TRICKS not trucks!

I do not have first-hand experience with the 7A15A but the input to the attenuator is similar to other products that require trucks or special tools to reach the BNC nut.

You might get lucky with needle-nose pliers to hold the nut and twist the BNC. It will only rotate a couple of degrees but if repeated you can loosen the nut. If you try to turn the nut with pliers you will likely slip and gouge and damage something.

A much safer approach requires modifying a wrench; cutting and grinding. See photograph at

/g/TekScopes/album?id=287576

Hey Keith,

I'm scrubbing through the calibration instructions, trying to remember what
I'd sussed out when I was looking into this.
The principle is that the CRT is set up against a reference sweep, whose
deflection factor D V/DIV has been measured using DLY_REF_0 & _1, using
you, the puny human, as a comparator. This sweep is then mated to the CRT
by adjusting the horizontal gains.
Subsequent sweep speeds are then set up by initiating a strawman sweep
using a strawman current Is that is close to the correct slope, then
measuring the strawman slope Ss V/SEC using the DLY_REF_0 and _1, again
with the human as a comparator. Given Is and Ss, it's then possible to
interpolate the correct I and S for the sweep.

Here are the important steps, and what I believe they do:
o) Verify that DLY_REF_0 and _1 are in concordance by lining up both
B-sweeps on a reference. I assume this will produce that dreaded LIMITS
error if the internal control voltages (aka DAC codes) don't line up fairly
precisely.
r) Find the slope of the reference sweep timing by aligning both B sweeps
on different timing signal reference markers.
aa) Adjust horizontal gain to fit the reference sweep precisely on CRT.
The CRT is now calibrated in horizontal D V/DIV deflection factor, and the
scope knows the deflection factor D.

ff et al) Measure the slope S of various timings the same way as in step r
(using the human as comparator). Given that the scope knows the reference
current producing S, it can interpolate the correct reference current to
calibrate S to the deflection factor D.

In the 2465, as Chuck mentions, the B sweep timings were set simply by
aligning time markers to the graticule.
In the 2465A and later, the calibration procedure for the B sweep works the
same way as the A sweep, except the B gate and a bench scope are used to
display the waveforms for the human comparator.
The way this has to work is by alternating B sweep delays, which should
still produce a trace on the DUT CRT.
The difference is that twiddling the delta and delta ref knobs here will
change the timing of the B-gate with respect to the timing signal, rather
than to show where on the A trace the B-trace sits.

jj et al) Measure the slope of B sweeps by overlaying two delayed versions
of the timing reference on a bench scope, then interpolate the correct
reference current as in ff).

And that's all I have to say about that (though let the truth prevail if I
haven't reasoned this out right :).

Siggi

On Wed, Jan 22, 2025 at 11:41?AM Keith via groups.io <keith=
[email protected]> wrote:

Hmm. It does rather look like you need to use an analog scope with a
delayed B timebase as the 'bench' scope, from reading Chucks's comment
#154417.

Time to read all of that thread...

- Keith


On Wed, Jan 22, 2025 at 04:27 PM, Sigur?ur ?sgeirsson wrote:

And perhaps I'm just totally wrong, and this is simply calibrating the B
time base and/or delay:
/g/TekScopes/topic/2465b_vert_cal_02_cal_01/29871399.
Chuck will know this better than I do, and I don't pretend to offhand
understand how the +-B error thang works.

Hmm. It does rather look like you need to use an analog scope with a delayed B timebase as the 'bench' scope, from reading Chucks's comment #154417.

Time to read all of that thread...

- Keith

On Wed, Jan 22, 2025 at 11:14?AM Sigur?ur ?sgeirsson via groups.io <siggi=
[email protected]> wrote:

On Wed, Jan 22, 2025 at 10:43?AM Sigur?ur ?sgeirsson via groups.io <siggi=
[email protected]> wrote:

Assuming this is calibrating something to do with the B sweep delay,
presumably you ought to be aligning two copies of the timing marks.

... on the bench scope ...

If you look at A1U850A, you'll see that DLY_REF_0 and _1 can both make
their way to the B-sweep DR (delay ref) pin, so presumably this is
calibrating out something to do with the alternate delay paths?
If you have the case off, you can verify this by looking at the control
signal on U850A while sitting at step (jj). If it's alternating, then the
two delay refs are being alternately routed to the B-sweep delay ref.
Note that since the control signal is under microcontroller-control, the
switching will be quite slow, so maybe you need to bump the persistence

on

your bench scope to see two instances of the time markers?

It occurs to me that alternatively you might be aligning the start time of
the B-sweep through two alternate paths. There is a mention in the ToO that
the B sweep can run concurrently with the A sweep, so perhaps the delay
reference is used to make sure the two sweeps are in time, whichever way
gates them.

... time passes ...

So I looked at the service manual for my 2467, which has essentially the
same instructions for step (jj), but it's only possible to route -1.25V or
the A-sweep delay reference to the B-sweep delay reference.
So, it's still possible that this is calibrating out something to do with
the two paths the B-sweep can be initiated. See page 3a-22, where it
discusses the BDCA signal. I could imagine alternating between the BDCA and
regular B delay sweep modes, adjusting the A and B delay reference voltages
in order to effectively measure the initiation delay of the B sweep through
the BDCA path.
Honestly, I just don't know. but again, if you probe the BDCA signal while
hanging out on the (jj) step, you'd be able to find out :).

And perhaps I'm just totally wrong, and this is simply calibrating the B
time base and/or delay:
/g/TekScopes/topic/2465b_vert_cal_02_cal_01/29871399.
Chuck will know this better than I do, and I don't pretend to offhand
understand how the +-B error thang works.

On Wed, Jan 22, 2025 at 10:43?AM Sigur?ur ?sgeirsson via groups.io <siggi=
[email protected]> wrote:

Assuming this is calibrating something to do with the B sweep delay,
presumably you ought to be aligning two copies of the timing marks.

... on the bench scope ...

If you look at A1U850A, you'll see that DLY_REF_0 and _1 can both make
their way to the B-sweep DR (delay ref) pin, so presumably this is
calibrating out something to do with the alternate delay paths?
If you have the case off, you can verify this by looking at the control
signal on U850A while sitting at step (jj). If it's alternating, then the
two delay refs are being alternately routed to the B-sweep delay ref.
Note that since the control signal is under microcontroller-control, the
switching will be quite slow, so maybe you need to bump the persistence on
your bench scope to see two instances of the time markers?

It occurs to me that alternatively you might be aligning the start time of
the B-sweep through two alternate paths. There is a mention in the ToO that
the B sweep can run concurrently with the A sweep, so perhaps the delay
reference is used to make sure the two sweeps are in time, whichever way
gates them.

... time passes ...

So I looked at the service manual for my 2467, which has essentially the
same instructions for step (jj), but it's only possible to route -1.25V or
the A-sweep delay reference to the B-sweep delay reference.
So, it's still possible that this is calibrating out something to do with
the two paths the B-sweep can be initiated. See page 3a-22, where it
discusses the BDCA signal. I could imagine alternating between the BDCA and
regular B delay sweep modes, adjusting the A and B delay reference voltages
in order to effectively measure the initiation delay of the B sweep through
the BDCA path.
Honestly, I just don't know. but again, if you probe the BDCA signal while
hanging out on the (jj) step, you'd be able to find out :).

On Wed, Jan 22, 2025 at 6:54?AM Keith via groups.io <keith=
[email protected]> wrote:

Then for cal step 17 set the Siglent pulse gen to 500mV p/p (is that
supposed to be 0 to +500mV, or -250mV to +250mV? I used the latter),

I believe TG501 has positive-going pulses, but I don't think it matters for
horizontal calibration. It is perhaps safer to use positive going pulses,
as the scope under calibration might use a fixed DC level trigger.
It does matter for vertical calibration that you use GND to the indicated
level, though.

- Err, which screen? Is that the 'Delta REF / DELAY POS' control? Where
are they if they are not 'on screen'?

Next, "When markers are superimposed"

- Again, on what screen?

I only did this once, years ago, for my 2467, and I just don't remember the
details. Keep it in mind that the instructions are written assuming you're
using another analog scope as a bench scope, presumably that's why the
instructions on how to set up delays and such. With a digital storage scope
you don't need to worry about any of that, as you can just position the
trigger wherever you want on the screen, and the timing calibration on the
bench scope is not going to be in question.
As to what you're supposed to align, I just don't remember, I hope someone
who's done this more recently than I steps in here.

Assuming this is calibrating something to do with the B sweep delay,
presumably you ought to be aligning two copies of the timing marks.
If you look at A1U850A, you'll see that DLY_REF_0 and _1 can both make
their way to the B-sweep DR (delay ref) pin, so presumably this is
calibrating out something to do with the alternate delay paths?
If you have the case off, you can verify this by looking at the control
signal on U850A while sitting at step (jj). If it's alternating, then the
two delay refs are being alternately routed to the B-sweep delay ref.
Note that since the control signal is under microcontroller-control, the
switching will be quite slow, so maybe you need to bump the persistence on
your bench scope to see two instances of the time markers?

Siggi: We had similar questions years ago when we did our frst full CAL.

Very important to do every section and be sure thhat CAL suceeds to write (rather than the deraed "out of range")

Most citical is the CTT option CAL.

1/ The gen spec for certain CAL sections is very specific, and needs the orig TEK cal gens or a very good replication.
IWe use the TEK and avoid the copies like siglent Chinese.

I suspect Chinese not produce the exact levels and duty cycle, freq required by TEK.

2/ The 246X/A/B CAL has been detailed extensivel especiall for the unlear steps and screens.

Search both this group and Tekscpes2 @ groups.io and EEVBLOG 2465 teardown for CAL errors and proceedure notes.

3/ Especiall Chuck Harris is the expert but banned from Tekscopes for unknown reasons years ago.

After your search and further work suggest to Ask Chhuck on Tekscops2.

Bon chance,

Jon

For Sale, wanted to buy group?????? Got a link for that?

73, and thanks,
Dave (NK7Z)

ARRL Volunteer Examiner
ARRL Technical Specialist, RFI
ARRL Asst. Director, NW Division, Technical Resources

Just in case people are not viewing the FS/WTB Group, I still have 468/465/465B for sale (in the UK only) on that group and am open to offers.

Check that Group site for full info.

Regards

Nigel

Hi Siggi,

Thanks, I've been able to run through the CAL01 (X) and CAL02 (Y), however I'm still lost at step 'jj'. I connect up a second scope as it says, with CH1 from the marker generator (in my case the Siglent) and CH2 coming from the Gate output of the 2465B, and set triggering to CH2.

Then for cal step 17 set the Siglent pulse gen to 500mV p/p (is that supposed to be 0 to +500mV, or -250mV to +250mV? I used the latter), 1uS period, 100nS pulse width. Then I see that waveform as expected on the second scope.

But next, the manual says:

"adjust the Delta control for roughly the listed number of markers over the center 8 divisions, then superimpose markers on bench scope screen"

- I've got the markers i.e. the pulse gen output visible on the bench scope, and the gate waveform, what does 'superimpose' mean? Have the two traces on top of each other?

It then says "Manually set SEC/DIV setting of bench scope to keep a usable time mark as listed in Table 5-3"

- I presum if just means keeping the pulse train on CH1 and the gate waveform on CH2 visible?

Then it says "Use IUT DELAY POS to bring markers on screen".

- Err, which screen? Is that the 'Delta REF / DELAY POS' control? Where are they if they are not 'on screen'?

Next, "When markers are superimposed"

- Again, on what screen?

I just skipped thru steps 17-34 as it was not clear how to do these steps. I do wish Tek had added some images of what you're supposed to be doing on the Table 5-3 steps. The waveforms after cal seem to have the correct amplitude and time with the A timebase, but probably the delayed timebase is not right as you mention.

- Keith