Date   
Re: 2215 avoiding future CRT damage

 

On Thu, Jul 5, 2018 at 01:19 pm, lop pol wrote:


CRT has been replaced and all works fine. This particular 2215 has no
regulator board. Is there any way to avoid damaging this new CRT? Would
keeping a low grid bias make any difference?
Thanks guys.
Make sure it has been modded according to SUP3010: http://www.hakanh.com/dl/docs/hardtofind/SUP3010.pdf
/Håkan

Re: PG506 trig out jitter?

Siggi
 

On Thu, 5 Jul 2018 at 15:04 Albert Otten <aodiversen@...> wrote:

The trigger output and the Hi Ampl output are in phase square waves. The
fast up-going edge of the trigger corresponds to the fast up-going edge of
the Hi Ampl when it switches from negative to zero.

Right - same polarity on the edges, thanks. The manual spells this out, I
guess I could have read it rather than speculate. But where's the fun in
that?


The slower down-going edge of the trigger corresponds to the down-going
edge of the Hi Ampl.
Mmmm, slower meaning non-reference. It's not clear to me why this edge
would be slower, but maybe that's just me. The output is driven towards the
negative, but the rising edge is entirely at the mercy of the 600 Ohm
output shunt and any capacitance downstream from there.


If you want to destroy your PG506 then try to"flip" the Hi Ampl output the
way you suggest.
Looks like I've misunderstood the point of the "ground" switching. The
STD/High output connector is insulated, and so doesn't have the shell of
the BNC connected directly to the case. The shell is in fact switched
between two different "grounds" depending on the mode, and I had somehow
assumed from there that the high-amplitude output was not referenced to
ground.
On a second reading of the schematics, it appears that this is not the
case. I'm not sure, but perhaps the switching is so that the shell of the
output connector is connected to the very center of a star grounding system
in STD amplitude mode? This would make sense as those are getting to be
quite low-level signals towards the bottom end of the range...

All that being said, flipping the output of the hi ampl output will "just"
short it through the common ground between oscilloscope and the PG. I doubt
this would destroy it - not that I'm about to try it :).


The proper way is to build in a level shifter in your pulse generator. See
the schematics of 067-0681-00.
Yups, that's what I did, but sadly (presumably) the slow rise of the high
ampl output is leading or contributing to jitter from sync out to the fast
edge that's 15 times the rise of the pulser.

Re: 2215 avoiding future CRT damage

Brendan
 

Exactly what I was looking for. Thank you

On Thu, Jul 5, 2018 at 02:25 pm, zenith5106 wrote:


On Thu, Jul 5, 2018 at 01:19 pm, lop pol wrote:


CRT has been replaced and all works fine. This particular 2215 has no
regulator board. Is there any way to avoid damaging this new CRT? Would
keeping a low grid bias make any difference?
Thanks guys.
Make sure it has been modded according to SUP3010:
http://www.hakanh.com/dl/docs/hardtofind/SUP3010.pdf
/Håkan

Re: 468 DSO Calibration/troubleshooting

Fabio Trevisan
 

OK Collin,
Now it makes some sense that there's no instruction to set the "NON STORE" to Off.
It's set to off at Section #2, step i, when it asks to set storage mode to "NORM".
Fine then... it means that during this step the scope is in full "digital" mode, and the waveform we're looking at is the digitized one.
regarding your triggering problem... well it does seem that it's being caused by something else, because if we think of the entire STORAGE triggering check / calibration instructions, it's rather minimalist.
It basically covers checks of the storage window mode (post trig and pre trig) and the A and B gates, and this one and only adjustment (for Storage NORM DC Bal).
I don't think the jitter is caused anywhere here, and from your description of when you try to align the rising edge of the 50KHz signal to the 2nd graticule line. that it comes out of trigger, that doesn't really make sense.
This fact alone suggests that the triggering point of the digital section is, level wise, completely unmatched to the analog section... Because, if you display this very same 50KHz in analog mode in this time base of 0.1ms, and set the trigger point of the 1st cycle at the 0 crossing... the 6th cycle will be dead on the correct spot (and so every one of the displayed cycles will be crossing the center line exactly at each of the HOR minor divisions).

And talking about your jitter / alias... Well, at 50 points per division (as the storage mode is expected to acquire/display), this 50KHz signal at 0.1ms/div would still have a healthy 10 points / cycle so, a jitter of +- 1 sample would be 1/10th of a minor division and, at this acquisition speed, much lower than the limit of the scope, I wouldn't expect nothing worse than +-1 sample.
Definitely there shouldn't be aliasing at play here either (with this healthy 10 sample / cycle). If much, a jitter of +- 0.05 div.

I will try to dig a little bit on the circuitry to see if I can come with any suggestion... but basically, from this point on, I don't think you're getting the calibration instructions wrong...or that you're missing something. It really seems that something is not working well on the digital triggering section.

KRgrds,

Fabio

On Thu, Jul 5, 2018 at 12:03 pm, Colin Herbert wrote:


Hi Fabio,
The difficulty with looking at a 50-KHZ at 0.1 ms/div is that the triggering
is really not that great and some aliasing is evident. I do see your point,
though and I have given it a go, but the jitter doesn't help and I can't get
any of the rising edges to align with the second vertical graticule line using
the A trigger level. What I have just noticed, though, is that the stable
triggering only takes place between the zero crossing and just after the next
crest and, oddly, it seems to be the wrong slope! That is, with the slope
switch in the + position, triggering is on the falling edge and vice versa.
The non-storage triggering is exactly the way it should be. I think there may
be something wrong, here.

With regard to the storage/non-storage buttons. They are all latched. Pushing
any of the storage buttons (Norm, Envelope, Avg and Save) releases any of the
other three and the Non-stope button. Pushing Non-store releases the storage
buttons. I think that's what you might expect.

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Fabio
Trevisan
Sent: 05 July 2018 19:29
To: TekScopes@groups.io
Subject: Re: [TekScopes] 468 DSO Calibration/troubleshooting

Hi Collin,
You're welcome... It's more challenging to solve puzzles when you're not
actually on the driver's seat.

Right out of the box I can't see a flaw in your reasoning... I confess I
didn't make the math that 50KHz at 0.1ms/div would give something like 50
cycles...
I agree it seems really silly to try to adjust the crossing of the waveform at
that particular cross-hair, with such dense waveform. 20us/div would really
make more sense in that respect.
Or maybe... they really meant it to be densely packed with cycles, so that we
could "disregard" the rising edge slope (at that density, the rising edge is
almost a vertical line, that we would only need to make sure is aligned to the
vertical graticule).
If there's no mistake in the instructions, it should have - at least -
mentioned that we should be aligning the leading edge of the 6th displayed
cycle, and not just "Align the leading edge"... that's too vague to say the
least.

Now, regarding my doubt whether the procedure is meant to be carried out in
storage mode or not, I have a doubt: How does the "NON STORE" button mode
works (mechanically)?
Is that when we press some of the STORAGE MODE buttons (say, NORM, ENVELOPE,
AVG, or SAVE), does it make the "NON STORE" button to pull out?
That would explain why there's no instruction to explicitly set the "NON
STORE" button to OFF (out).

KRgrds,

Fabio





On Thu, Jul 5, 2018 at 10:07 am, Colin Herbert wrote:


Hi Fabio,

Firstly, thank you for giving this some thought. Some of my observations:

1. Check STORAGE WINDOW Operation. This all works fine, except that when
going
to "d. set STORAGE WINDOW PRE TRIG" the triggering jitter becomes quite
noticeable; it is less so in POST TRIG.
2. Check A and B+ GATES.
Set NON-STORE On; A TIME/DIV 0.1 ms; B TIME/DIV 20 us. All works as
expected,
except for the jitter when in NORM storage mode - Non-storage there is a
rock-solid trace with no jitter at all.
3. Check/Adjust Storage NORM Trigger DC Balance (R126)
Set CH1 VOLTS/DIV 5mV; HORIZ DISPLAY A. Remember that the A sweep is still
at 0.1 ms/DIV and so there are some 50 full cycles of a 50-kHz sine-wave.
Trying to set anything with the A TRIGGER LEVEL is nigh on impossible. I
think
the sweep should be A at 20 us/DIV, showing ten full cycles. The problem now
is that trying to align the leading edge with the second vertical graticule
line at the horizontal centre graticule line results in loss of triggering.
This alignment can be done using the horizontal position control, however.
When aligned in this way, switching between AC and DC Trigger coupling of
the
A sweep shows no movement.

Have I achieved what is required, or am I again missing something?

It is a pity that Reed Dickinson hasn't seen this thread, as I think he is a
bit of an expert on the 468 and he certainly holds them in some respect.
However, I repeat my thanks to you, Fabio.

Regards, Colin.

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Fabio
Trevisan
Sent: 05 July 2018 17:09
To: TekScopes@groups.io
Subject: Re: [TekScopes] 468 DSO Calibration/troubleshooting

Hello Collin,

Regarding my last statement (the P.S.), that this check should be made in
"non-store" mode, I'm giving second thoughts at it.
I`m not sure yet, but I just found out that there are two "NORM triggering
DC
balance" adjustments... one on the analog side and another one on the
storage
side...
So, it seems weird that we could even be able to adjust the STORAGE NORM
triggering DC balance in any mode that isn't a storage mode.

On the other hand, I may still be correct on my initial assumption, because
the flow of the instructions and the explicit instruction to set "NON STORE"
to ON, at Section #2, step g.
I`m only not sure if that adjustment (R126) would be even doable while in
NON
STORE mode...

I`ll get back to it as soon as I can dig a little bit more on the manual.

Rgrds,

Fabio



On Thu, Jul 5, 2018 at 08:23 am, Fabio Trevisan wrote:


Hello Colin,

I don't own a 468 and have no particular experience with it, but I have
the
manuals (in PDF form) and since your doubt is related to understaing of
the
instructions, I decided to give it a try and see if I could make sense out
of
this part of the instruction that you're doubtful at.

At this step, the only thing that doesn't seem really clear to me is why
it
asks specifically to align the leading edge of the sine-wave to the 2nd
graticule line (why the 2nd.???)..
But, regardless of not understanding that, I think the purpose of this
calibration step is clear... Is to make a "differential" assessment of the
triggering level shift, between using AC triggering coupling and DC
triggering
coupling...
So, basically what it is asking for, is for you to make sure that the
triggering point doesn't move between AC and DC coupling, when you're
actually
feeding a signal that already swings about 0V...
I mean, if the input signal is swinging about 0V (i.e. if it doesn't
contain
a
DC level), changing the triggering coupling from AC to DC should not make
any
difference, and therefore, the triggering point, whatever it was set to
before
switching to DC, the wave form must remain in the same position.
If the waveform shifts horizontally, than it means that the triggering
point
"seen" by the triggering circuit have changed when switching over from AC
to
DC, which it shouldn't.

Giving second thoughts to the instruction, it's not much different than
adjusting the Norm DC triggering balance of a 464 (which I own), and
probably
the same as the 465 (more common).
the only difference is that, for the 464, we're asked for looking at the
very
beginning of the sweep, and not at the 2nd vertical graticule line (i.e. 1
division after the sweep actually started).
This difference in procedure (from the non store scope), doesn't actually
matter to what the DC balance adjustment is doing (which is nothing more
than
shifting the DC level of the actual signal being fed to the triggering
input
buffer, with the intent to making it match with the level of the same
signal
when AC coupled).
The only reason I think they're doing that (adjusting at the 2nd vertical
graticule line iso at the beginning of the sweep), is because this point
is
about the actual point on the display where the triggering point of the
digital stored signal is supposed to be displayed.

P.S. Also note that, although this adjustment step is called "Check /
Adjust
STORAGE NORM Trigger DC balance", by following the instructions coming
from
the previous steps, I understand (it's my conclusion though) that this
adjustment is not meant to be performed in storage mode.
The previous section, "#2 Check A and B+ gates", at step g. it asks you
to
set the "NON STORE" button to ON position... and then it doesn't ever ask
you
to change it to OFF, so, by the flow of the procedure, the #3 check is to
be
performed in NON STORE mode.
Therefore, this jitter that you mentioned you're getting on storage mode
should not interfere with you performing this adjustment (because it's
done
in
NON STORE mode).

Now, talking about this jitter... I don't think it has any relation to
this
adjustment, and it's probably not going to be fixed by setting this
adjustment
right.

I hope I was able to help you somehow.

KRgrds,

Fabio




On Tue, Jul 3, 2018 at 10:08 am, Colin Herbert wrote:


I have got through the calibration/adjustment procedure up to "Storage
Triggering". My problems now are twofold. I can't understand Section #3
-
"Check/Adjust Storage NORM Trigger DC Balance" (P4-89 in the manual).
Apart
from the fact that the storage triggering has a deal of jitter, I can't
get
step (e) to make sense. I am supposed to "use the A TRIGGER LEVEL to
align
the
point where the sine-wave's leading edge intersects the center
horizontal
graticule line with the 2nd vertical graticule line". Because of the the
jitter and the fact that the triggering fails when I adjust the A
TRIGGER
LEVEL, this is impossible. Am I doing something wrong (quite possible),
or
is
the manual giving me the wrong information? Help!
If anyone has an idea of how I can eliminate the jitter, that would be
nice,
too. There is no jitter in "NON STORE" operation. I was hoping it would
just
be something simple like a switch needing cleaning, or an IC needing
reseating, but nothing has given me any clues so far...
Colin.






634 Monitor HV board issue

Adrian
 

Just when things were going so well with the 7912AD - with grateful thanks to all the folks here for their help - the pesky 634 Monitor ups and dies on me!
Picture vanishes and investigation shows the fuse supplying 20VDC to the A4 High Voltage board is blown.
Replaced it with an ammeter and it fired up but drawing a high current, 1.8A rather than the 900mA expected.
Picture was back but the current started increasing so I shut it down.
I've checked every semiconductor on the board to the extent that I see diode junctions where I should, all Rs, Cs and Ls look ok and the transformer has continuity and no inter-winding shorts.

Observations:
1/ With no 20VDC present the 'local' +5VDC and +15V[1] busses were at +2.2 and +8V, The 15V collapse would be expected I think as the 741 error opamp will be driving it's output pin to the endstop (15V rail) into a 580ohm load and the rail is 'isolated' from the instrument +15V supply by a series 510 ohm resistor, the +5V collapse is more of a puzzle?

2/ The voltage multiplier output monitor pin is shown as a 300Mohm/300kOhm divider referenced to -15VDC but I measure 210kOhm at the low end with the parallel VDR disconnected.

3/ Perhaps expected in this sort of 'open loop' configuration but the voltage adjustment pot can only swing the inverting input pin of the 741 from -7 to -10V (the pot wiper has the full +/-15V)

4/ The transformer 20V primary winding has a very low DC resistance approx 100 mOhm - lower than I would have guessed but may be ok?

So the question: Is my gloomy prediction that the voltage multiplier module is the issue likely correct: Supplementary question, how do I confirm this and then what to do about it?

Many thanks,
Adrian

Re: PG506 trig out jitter?

Albert Otten
 

Hi Siggi,

This time I didn't study the manual but just looked dual-trace at the waveforms of trigger and Hi Ampl. Trigger always properly terminated. But I confused the traces when saying that the down-going edge of the trigger was slow; that was the terminated Hi Ampl. I checked again. It's nice to see how the terminated Hi Ampl negative going edge "climbs" along the same path to its maximum, when you vary the amplitude knob.
When Hi Amp is unterminated and loaded with coax cable then the rise and fall are almost symmetrically, both governed by the same RC time as mentioned already. I found about 200 ns rise time when using about 1 m coax which measured 128 pF including the scope input. This seems not far off at 600 Ohm.

Albert

On Thu, Jul 5, 2018 at 02:26 pm, Siggi wrote:


On Thu, 5 Jul 2018 at 15:04 Albert Otten <aodiversen@...> wrote:

The trigger output and the Hi Ampl output are in phase square waves. The
fast up-going edge of the trigger corresponds to the fast up-going edge of
the Hi Ampl when it switches from negative to zero.

Right - same polarity on the edges, thanks. The manual spells this out, I
guess I could have read it rather than speculate. But where's the fun in
that?


The slower down-going edge of the trigger corresponds to the down-going
edge of the Hi Ampl.
Mmmm, slower meaning non-reference. It's not clear to me why this edge
would be slower, but maybe that's just me. The output is driven towards the
negative, but the rising edge is entirely at the mercy of the 600 Ohm
output shunt and any capacitance downstream from there.

Another Soviet plugin: 7CT1N curve tracer equivalent Я4С-92

cmjones01
 

It was with some excitement that I unpacked today's new acquisition. From a surplus dealer in Ukraine, via some helpful friends in that country, I've got my hands on the Я4С-92, the Soviet version of the 7CT1N curve tracer plugin. in its original transit case with an almost complete set of adapters and its original manual and calibration certificate dated 1988! It's not new old stock and has definitely been used, but the seals on the plugin are intact.

There are five different adapters which fit on the front of the plugin, one for two-lead devices and the others for various transistors and FETs. They all have two buttons for comparing devices, and little plastic lids with a microswitch to enable the tracer when they're safely closed. The only bits which seem to be missing are a couple of connector blocks which seem to have something to do with the calibration process, but I'm not too worried about those.

I have to say that the Soviet makers have the edge over Tektronix when it comes to the sheer robustness of the packaging. It's a plywood box with steel corner protectors, lined with polystyrene and foam to fit all the parts. The whole thing weighs about 10.5kg (23lb).

Pictures here:
https://groups.io/g/TekScopes/album?id=62315

It'll be fun learning to drive it, and it will be really useful in the lab, too.

Chris

Replace button on 1140x

Pete Lancashire
 

Has anyone replaced one of the control buttons on a 1140x ?

https://photos.app.goo.gl/KaWtkFv4a7bBJrZt8

Just Thought I would ask before trying to get the front off.

-pete

Re: Another Soviet plugin: 7CT1N curve tracer equivalent Я4С-92

Dave Casey
 

Interesting....but how does it do X-Y mode?

Dave Casey

On Fri, Jul 6, 2018 at 6:01 AM, cmjones01 <chris@...> wrote:

It was with some excitement that I unpacked today's new acquisition. From
a surplus dealer in Ukraine, via some helpful friends in that country, I've
got my hands on the Я4С-92, the Soviet version of the 7CT1N curve tracer
plugin. in its original transit case with an almost complete set of
adapters and its original manual and calibration certificate dated 1988!
It's not new old stock and has definitely been used, but the seals on the
plugin are intact.

There are five different adapters which fit on the front of the plugin,
one for two-lead devices and the others for various transistors and FETs.
They all have two buttons for comparing devices, and little plastic lids
with a microswitch to enable the tracer when they're safely closed. The
only bits which seem to be missing are a couple of connector blocks which
seem to have something to do with the calibration process, but I'm not too
worried about those.

I have to say that the Soviet makers have the edge over Tektronix when it
comes to the sheer robustness of the packaging. It's a plywood box with
steel corner protectors, lined with polystyrene and foam to fit all the
parts. The whole thing weighs about 10.5kg (23lb).

Pictures here:
https://groups.io/g/TekScopes/album?id=62315

It'll be fun learning to drive it, and it will be really useful in the
lab, too.

Chris



Re: Another Soviet plugin: 7CT1N curve tracer equivalent ?4?-92

Craig Sawyers <c.sawyers@...>
 

I'm massively impressed with the packaging - and with the very nicely engineered adaptors.

I have to say that the Soviet makers have the edge over Tektronix when it comes to the sheer
robustness of the packaging. It's a plywood box with steel corner protectors, lined with polystyrene
and foam to fit all the parts. The whole thing weighs about 10.5kg (23lb).

Pictures here:
https://groups.io/g/TekScopes/album?id=62315

It'll be fun learning to drive it, and it will be really useful in the lab, too.

Chris

Re: Another Soviet plugin: 7CT1N curve tracer equivalent Я4С-92

cmjones01
 

Good question, I wondered that too. I've just tried out the plugin in a mainframe for the first time and noticed two things. First, it has readout! The current and voltage per division are displayed, together with the mode - 'n' for N-type FETs and 'npn' for NPN bipolars, and so on.

It doesn't need help from any other plugins to do X-Y mode, so the plugin interface must have been changed from the Tek one (though I've already observed that a lot of the signals are in the same places). The plugin has a 'measure' button which seems to enable and disable it. I've no idea how it interacts with having a timebase in the horiztontal slot. Perhaps it's handled gracefully, perhaps it all becomes a terrible mess, I'll have to try it at some point.

There's a picture of the tracer in action on a pair of IRLB3034 MOSFETs I found lying around on the bench. They're switching MOSFETs so they don't make very nice curves, but it's possible to see that the two start to switch on at different gate voltages. I presume the looping visible is because the slope of drain current against gate voltage is so steep, so even the tiniest variation in gate voltage results in visible loop.

https://groups.io/g/TekScopes/photo/62315/3?p=Name,,,20,1,0,0

A neat feature is that device 'A' is displayed with a solid trace and device 'B' gets a dotted one so you can tell them apart. The buttons on the adapter each *disable* one of the devices momentarily, otherwise they're both displayed all the time.

Chris

On Fri, Jul 6, 2018 at 05:22 am, Dave Casey wrote:

Interesting....but how does it do X-Y mode?

Dave Casey

On Fri, Jul 6, 2018 at 6:01 AM, cmjones01 <chris@...> wrote:

It was with some excitement that I unpacked today's new acquisition. From
a surplus dealer in Ukraine, via some helpful friends in that country, I've
got my hands on the Я4С-92, the Soviet version of the 7CT1N curve tracer
plugin. in its original transit case with an almost complete set of
adapters and its original manual and calibration certificate dated 1988!
It's not new old stock and has definitely been used, but the seals on the
plugin are intact.

There are five different adapters which fit on the front of the plugin,
one for two-lead devices and the others for various transistors and FETs.
They all have two buttons for comparing devices, and little plastic lids
with a microswitch to enable the tracer when they're safely closed. The
only bits which seem to be missing are a couple of connector blocks which
seem to have something to do with the calibration process, but I'm not too
worried about those.

I have to say that the Soviet makers have the edge over Tektronix when it
comes to the sheer robustness of the packaging. It's a plywood box with
steel corner protectors, lined with polystyrene and foam to fit all the
parts. The whole thing weighs about 10.5kg (23lb).

Pictures here:
https://groups.io/g/TekScopes/album?id=62315

It'll be fun learning to drive it, and it will be really useful in the
lab, too.

Chris



Re: Another Soviet plugin: 7CT1N curve tracer equivalent Я4С-92

ArtekManuals
 

Chris

I think you said you had the manual as well when you get a chance perhaps you can scan the schematics and post them here or on KO4BB. It would be interesting to see how they accomplished some of these features

Cheers
Dave
manuals@...

On 7/6/2018 8:50 AM, cmjones01 wrote:
Good question, I wondered that too. I've just tried out the plugin in a mainframe for the first time and noticed two things. First, it has readout! The current and voltage per division are displayed, together with the mode - 'n' for N-type FETs and 'npn' for NPN bipolars, and so on.

It doesn't need help from any other plugins to do X-Y mode, so the plugin interface must have been changed from the Tek one (though I've already observed that a lot of the signals are in the same places). The plugin has a 'measure' button which seems to enable and disable it. I've no idea how it interacts with having a timebase in the horiztontal slot. Perhaps it's handled gracefully, perhaps it all becomes a terrible mess, I'll have to try it at some point.

There's a picture of the tracer in action on a pair of IRLB3034 MOSFETs I found lying around on the bench. They're switching MOSFETs so they don't make very nice curves, but it's possible to see that the two start to switch on at different gate voltages. I presume the looping visible is because the slope of drain current against gate voltage is so steep, so even the tiniest variation in gate voltage results in visible loop.

https://groups.io/g/TekScopes/photo/62315/3?p=Name,,,20,1,0,0

A neat feature is that device 'A' is displayed with a solid trace and device 'B' gets a dotted one so you can tell them apart. The buttons on the adapter each *disable* one of the devices momentarily, otherwise they're both displayed all the time.

Chris

On Fri, Jul 6, 2018 at 05:22 am, Dave Casey wrote:
Interesting....but how does it do X-Y mode?

Dave Casey

On Fri, Jul 6, 2018 at 6:01 AM, cmjones01 <chris@...> wrote:

It was with some excitement that I unpacked today's new acquisition. From
a surplus dealer in Ukraine, via some helpful friends in that country, I've
got my hands on the Я4С-92, the Soviet version of the 7CT1N curve tracer
plugin. in its original transit case with an almost complete set of
adapters and its original manual and calibration certificate dated 1988!
It's not new old stock and has definitely been used, but the seals on the
plugin are intact.

There are five different adapters which fit on the front of the plugin,
one for two-lead devices and the others for various transistors and FETs.
They all have two buttons for comparing devices, and little plastic lids
with a microswitch to enable the tracer when they're safely closed. The
only bits which seem to be missing are a couple of connector blocks which
seem to have something to do with the calibration process, but I'm not too
worried about those.

I have to say that the Soviet makers have the edge over Tektronix when it
comes to the sheer robustness of the packaging. It's a plywood box with
steel corner protectors, lined with polystyrene and foam to fit all the
parts. The whole thing weighs about 10.5kg (23lb).

Pictures here:
https://groups.io/g/TekScopes/album?id=62315

It'll be fun learning to drive it, and it will be really useful in the
lab, too.

Chris



--
Dave
Manuals@...
www.ArtekManuals.com

Re: 2215 avoiding future CRT damage

Vincent Trouilliez
 

Thanks a lot for this document Hakan, didn't know about this problem !

As it happens I just got a 2215 the other day, working on it as we speak... just checked, it's smack in the middle of the affected S/N range (mine is #20521), and it appears not to have been moded : no sticker at the back, and the transformer looks stock : still in revision -00 and the wire has not been unwound by one turn.

So my CRT / filament is cooked then, by now, after nearly 40 years of use... oh well... not much I can do about it, but at least if I find the trace too dim at fast sweep speeds (haven't checked specifically for that yet), I will know why and won't waste trying to "fix"/troubleshoot something that just can't be cured ! :-(


Vincent Trouilliez

Re: Another Soviet plugin: 7CT1N curve tracer equivalent Я4С-92

cmjones01
 

Yes, I do have the manual which includes schematics (and even the winding details of the power converter transformer!). I definitely want to scan the schematics when I get chance. My old office had a really good scanner, and sadly the new one doesn't so I'll have to go to the copy shop down the road.

The manual runs to 78 pages plus schematics which are all odd sizes.

Incidentally, browsing the manual just now, it becomes clear how the X-Y mode is implemented. There's an X output on pins 15A/B of the plugin interface, and a Y output on pins 25A/B. The vertical amplifier plugin also has its signal output on 25A/B, which differs from the Tek allocation (11A/B). Trigger output is on 13A/B the same as Tek, though.

The mainframe has an X-axis switch for each plugin as well as a Y-axis switch, it turns out, so plugins are allowed to generate both X and Y signals. Interesting.

I wonder how the
Chris

On Fri, Jul 6, 2018 at 06:32 am, Artekmedia wrote:
I think you said you had the manual as well when you get a chance
perhaps you can scan the schematics and post them here or on KO4BB. It
would be interesting to see how they accomplished some of these features

Cheers
Dave
manuals@...

On 7/6/2018 8:50 AM, cmjones01 wrote:
Good question, I wondered that too. I've just tried out the plugin in a
mainframe for the first time and noticed two things. First, it has readout!
The current and voltage per division are displayed, together with the mode -
'n' for N-type FETs and 'npn' for NPN bipolars, and so on.

It doesn't need help from any other plugins to do X-Y mode, so the plugin
interface must have been changed from the Tek one (though I've already
observed that a lot of the signals are in the same places). The plugin has a
'measure' button which seems to enable and disable it. I've no idea how it
interacts with having a timebase in the horiztontal slot. Perhaps it's handled
gracefully, perhaps it all becomes a terrible mess, I'll have to try it at
some point.

There's a picture of the tracer in action on a pair of IRLB3034 MOSFETs I
found lying around on the bench. They're switching MOSFETs so they don't make
very nice curves, but it's possible to see that the two start to switch on at
different gate voltages. I presume the looping visible is because the slope of
drain current against gate voltage is so steep, so even the tiniest variation
in gate voltage results in visible loop.

https://groups.io/g/TekScopes/photo/62315/3?p=Name,,,20,1,0,0

A neat feature is that device 'A' is displayed with a solid trace and device
'B' gets a dotted one so you can tell them apart. The buttons on the adapter
each *disable* one of the devices momentarily, otherwise they're both
displayed all the time.

Chris

On Fri, Jul 6, 2018 at 05:22 am, Dave Casey wrote:
Interesting....but how does it do X-Y mode?

Dave Casey

On Fri, Jul 6, 2018 at 6:01 AM, cmjones01 <chris@...> wrote:

It was with some excitement that I unpacked today's new acquisition. From
a surplus dealer in Ukraine, via some helpful friends in that country,
I've
got my hands on the Я4С-92, the Soviet version of the 7CT1N curve tracer
plugin. in its original transit case with an almost complete set of
adapters and its original manual and calibration certificate dated 1988!
It's not new old stock and has definitely been used, but the seals on the
plugin are intact.

There are five different adapters which fit on the front of the plugin,
one for two-lead devices and the others for various transistors and FETs.
They all have two buttons for comparing devices, and little plastic lids
with a microswitch to enable the tracer when they're safely closed. The
only bits which seem to be missing are a couple of connector blocks which
seem to have something to do with the calibration process, but I'm not too
worried about those.

I have to say that the Soviet makers have the edge over Tektronix when it
comes to the sheer robustness of the packaging. It's a plywood box with
steel corner protectors, lined with polystyrene and foam to fit all the
parts. The whole thing weighs about 10.5kg (23lb).

Pictures here:
https://groups.io/g/TekScopes/album?id=62315

It'll be fun learning to drive it, and it will be really useful in the
lab, too.

Chris




--
Dave
Manuals@...
www.ArtekManuals.com


Re: PG506 trig out jitter?

Siggi
 

On Fri, 6 Jul 2018 at 04:17 Albert Otten <aodiversen@...> wrote:

This time I didn't study the manual but just looked dual-trace at the
waveforms of trigger and Hi Ampl. Trigger always properly terminated. But I
confused the traces when saying that the down-going edge of the trigger was
slow; that was the terminated Hi Ampl. I checked again. It's nice to see
how the terminated Hi Ampl negative going edge "climbs" along the same path
to its maximum, when you vary the amplitude knob.
When Hi Amp is unterminated and loaded with coax cable then the rise and
fall are almost symmetrically, both governed by the same RC time as
mentioned already. I found about 200 ns rise time when using about 1 m coax
which measured 128 pF including the scope input. This seems not far off at
600 Ohm.
I took a look at the (un-terminated) hi-rise output of the PG506 and it was
pretty slow - I forget how slow. It doesn't help when the TD pulser is the
"load" on there, and
when I look at the time from trigger out to TD pulser edge, it's on the
order of 600ns. I guess it's a bit of hack to use the hi-rise output of the
PG506 as a power supply for a pulser :). Clearly this arrangement won't
work for looking at the TD edge with a sampler. Either I need a delay line,
or else a different TD pulser, one with a stable pre-trigger.

Re: 468 DSO Calibration/troubleshooting

Colin Herbert
 

Hi Fabio,
I have now completed the "STORAGE HORIZONTAL" section of the Calibration procedure. Absolutely everything checked out as well within tolerance, until I got to the item 4 "Check Jitter Correction". This all checked out good, too, except that while there was no jitter generally on the right-hand side of the screen, it could be seen for the first two or so cycles. This was most obvious when using 50 kHz sinewave, 20 us/DIV, 2 mV/DIV, and X10 MAG. Again the centre part of the display was within specification, but the first two or so full cycles showed noticeable jitter.
Colin.

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Fabio Trevisan
Sent: 05 July 2018 23:35
To: TekScopes@groups.io
Subject: Re: [TekScopes] 468 DSO Calibration/troubleshooting

OK Collin,
Now it makes some sense that there's no instruction to set the "NON STORE" to Off.
It's set to off at Section #2, step i, when it asks to set storage mode to "NORM".
Fine then... it means that during this step the scope is in full "digital" mode, and the waveform we're looking at is the digitized one.
regarding your triggering problem... well it does seem that it's being caused by something else, because if we think of the entire STORAGE triggering check / calibration instructions, it's rather minimalist.
It basically covers checks of the storage window mode (post trig and pre trig) and the A and B gates, and this one and only adjustment (for Storage NORM DC Bal).
I don't think the jitter is caused anywhere here, and from your description of when you try to align the rising edge of the 50KHz signal to the 2nd graticule line. that it comes out of trigger, that doesn't really make sense.
This fact alone suggests that the triggering point of the digital section is, level wise, completely unmatched to the analog section... Because, if you display this very same 50KHz in analog mode in this time base of 0.1ms, and set the trigger point of the 1st cycle at the 0 crossing... the 6th cycle will be dead on the correct spot (and so every one of the displayed cycles will be crossing the center line exactly at each of the HOR minor divisions).

And talking about your jitter / alias... Well, at 50 points per division (as the storage mode is expected to acquire/display), this 50KHz signal at 0.1ms/div would still have a healthy 10 points / cycle so, a jitter of +- 1 sample would be 1/10th of a minor division and, at this acquisition speed, much lower than the limit of the scope, I wouldn't expect nothing worse than +-1 sample.
Definitely there shouldn't be aliasing at play here either (with this healthy 10 sample / cycle). If much, a jitter of +- 0.05 div.

I will try to dig a little bit on the circuitry to see if I can come with any suggestion... but basically, from this point on, I don't think you're getting the calibration instructions wrong...or that you're missing something. It really seems that something is not working well on the digital triggering section.

KRgrds,

Fabio


On Thu, Jul 5, 2018 at 12:03 pm, Colin Herbert wrote:


Hi Fabio,
The difficulty with looking at a 50-KHZ at 0.1 ms/div is that the triggering
is really not that great and some aliasing is evident. I do see your point,
though and I have given it a go, but the jitter doesn't help and I can't get
any of the rising edges to align with the second vertical graticule line using
the A trigger level. What I have just noticed, though, is that the stable
triggering only takes place between the zero crossing and just after the next
crest and, oddly, it seems to be the wrong slope! That is, with the slope
switch in the + position, triggering is on the falling edge and vice versa.
The non-storage triggering is exactly the way it should be. I think there may
be something wrong, here.

With regard to the storage/non-storage buttons. They are all latched. Pushing
any of the storage buttons (Norm, Envelope, Avg and Save) releases any of the
other three and the Non-stope button. Pushing Non-store releases the storage
buttons. I think that's what you might expect.

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Fabio
Trevisan
Sent: 05 July 2018 19:29
To: TekScopes@groups.io
Subject: Re: [TekScopes] 468 DSO Calibration/troubleshooting

Hi Collin,
You're welcome... It's more challenging to solve puzzles when you're not
actually on the driver's seat.

Right out of the box I can't see a flaw in your reasoning... I confess I
didn't make the math that 50KHz at 0.1ms/div would give something like 50
cycles...
I agree it seems really silly to try to adjust the crossing of the waveform at
that particular cross-hair, with such dense waveform. 20us/div would really
make more sense in that respect.
Or maybe... they really meant it to be densely packed with cycles, so that we
could "disregard" the rising edge slope (at that density, the rising edge is
almost a vertical line, that we would only need to make sure is aligned to the
vertical graticule).
If there's no mistake in the instructions, it should have - at least -
mentioned that we should be aligning the leading edge of the 6th displayed
cycle, and not just "Align the leading edge"... that's too vague to say the
least.

Now, regarding my doubt whether the procedure is meant to be carried out in
storage mode or not, I have a doubt: How does the "NON STORE" button mode
works (mechanically)?
Is that when we press some of the STORAGE MODE buttons (say, NORM, ENVELOPE,
AVG, or SAVE), does it make the "NON STORE" button to pull out?
That would explain why there's no instruction to explicitly set the "NON
STORE" button to OFF (out).

KRgrds,

Fabio





On Thu, Jul 5, 2018 at 10:07 am, Colin Herbert wrote:


Hi Fabio,

Firstly, thank you for giving this some thought. Some of my observations:

1. Check STORAGE WINDOW Operation. This all works fine, except that when
going
to "d. set STORAGE WINDOW PRE TRIG" the triggering jitter becomes quite
noticeable; it is less so in POST TRIG.
2. Check A and B+ GATES.
Set NON-STORE On; A TIME/DIV 0.1 ms; B TIME/DIV 20 us. All works as
expected,
except for the jitter when in NORM storage mode - Non-storage there is a
rock-solid trace with no jitter at all.
3. Check/Adjust Storage NORM Trigger DC Balance (R126)
Set CH1 VOLTS/DIV 5mV; HORIZ DISPLAY A. Remember that the A sweep is still
at 0.1 ms/DIV and so there are some 50 full cycles of a 50-kHz sine-wave.
Trying to set anything with the A TRIGGER LEVEL is nigh on impossible. I
think
the sweep should be A at 20 us/DIV, showing ten full cycles. The problem now
is that trying to align the leading edge with the second vertical graticule
line at the horizontal centre graticule line results in loss of triggering.
This alignment can be done using the horizontal position control, however.
When aligned in this way, switching between AC and DC Trigger coupling of
the
A sweep shows no movement.

Have I achieved what is required, or am I again missing something?

It is a pity that Reed Dickinson hasn't seen this thread, as I think he is a
bit of an expert on the 468 and he certainly holds them in some respect.
However, I repeat my thanks to you, Fabio.

Regards, Colin.

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Fabio
Trevisan
Sent: 05 July 2018 17:09
To: TekScopes@groups.io
Subject: Re: [TekScopes] 468 DSO Calibration/troubleshooting

Hello Collin,

Regarding my last statement (the P.S.), that this check should be made in
"non-store" mode, I'm giving second thoughts at it.
I`m not sure yet, but I just found out that there are two "NORM triggering
DC
balance" adjustments... one on the analog side and another one on the
storage
side...
So, it seems weird that we could even be able to adjust the STORAGE NORM
triggering DC balance in any mode that isn't a storage mode.

On the other hand, I may still be correct on my initial assumption, because
the flow of the instructions and the explicit instruction to set "NON STORE"
to ON, at Section #2, step g.
I`m only not sure if that adjustment (R126) would be even doable while in
NON
STORE mode...

I`ll get back to it as soon as I can dig a little bit more on the manual.

Rgrds,

Fabio



On Thu, Jul 5, 2018 at 08:23 am, Fabio Trevisan wrote:


Hello Colin,

I don't own a 468 and have no particular experience with it, but I have
the
manuals (in PDF form) and since your doubt is related to understaing of
the
instructions, I decided to give it a try and see if I could make sense out
of
this part of the instruction that you're doubtful at.

At this step, the only thing that doesn't seem really clear to me is why
it
asks specifically to align the leading edge of the sine-wave to the 2nd
graticule line (why the 2nd.???)..
But, regardless of not understanding that, I think the purpose of this
calibration step is clear... Is to make a "differential" assessment of the
triggering level shift, between using AC triggering coupling and DC
triggering
coupling...
So, basically what it is asking for, is for you to make sure that the
triggering point doesn't move between AC and DC coupling, when you're
actually
feeding a signal that already swings about 0V...
I mean, if the input signal is swinging about 0V (i.e. if it doesn't
contain
a
DC level), changing the triggering coupling from AC to DC should not make
any
difference, and therefore, the triggering point, whatever it was set to
before
switching to DC, the wave form must remain in the same position.
If the waveform shifts horizontally, than it means that the triggering
point
"seen" by the triggering circuit have changed when switching over from AC
to
DC, which it shouldn't.

Giving second thoughts to the instruction, it's not much different than
adjusting the Norm DC triggering balance of a 464 (which I own), and
probably
the same as the 465 (more common).
the only difference is that, for the 464, we're asked for looking at the
very
beginning of the sweep, and not at the 2nd vertical graticule line (i.e. 1
division after the sweep actually started).
This difference in procedure (from the non store scope), doesn't actually
matter to what the DC balance adjustment is doing (which is nothing more
than
shifting the DC level of the actual signal being fed to the triggering
input
buffer, with the intent to making it match with the level of the same
signal
when AC coupled).
The only reason I think they're doing that (adjusting at the 2nd vertical
graticule line iso at the beginning of the sweep), is because this point
is
about the actual point on the display where the triggering point of the
digital stored signal is supposed to be displayed.

P.S. Also note that, although this adjustment step is called "Check /
Adjust
STORAGE NORM Trigger DC balance", by following the instructions coming
from
the previous steps, I understand (it's my conclusion though) that this
adjustment is not meant to be performed in storage mode.
The previous section, "#2 Check A and B+ gates", at step g. it asks you
to
set the "NON STORE" button to ON position... and then it doesn't ever ask
you
to change it to OFF, so, by the flow of the procedure, the #3 check is to
be
performed in NON STORE mode.
Therefore, this jitter that you mentioned you're getting on storage mode
should not interfere with you performing this adjustment (because it's
done
in
NON STORE mode).

Now, talking about this jitter... I don't think it has any relation to
this
adjustment, and it's probably not going to be fixed by setting this
adjustment
right.

I hope I was able to help you somehow.

KRgrds,

Fabio




On Tue, Jul 3, 2018 at 10:08 am, Colin Herbert wrote:


I have got through the calibration/adjustment procedure up to "Storage
Triggering". My problems now are twofold. I can't understand Section #3
-
"Check/Adjust Storage NORM Trigger DC Balance" (P4-89 in the manual).
Apart
from the fact that the storage triggering has a deal of jitter, I can't
get
step (e) to make sense. I am supposed to "use the A TRIGGER LEVEL to
align
the
point where the sine-wave's leading edge intersects the center
horizontal
graticule line with the 2nd vertical graticule line". Because of the the
jitter and the fact that the triggering fails when I adjust the A
TRIGGER
LEVEL, this is impossible. Am I doing something wrong (quite possible),
or
is
the manual giving me the wrong information? Help!
If anyone has an idea of how I can eliminate the jitter, that would be
nice,
too. There is no jitter in "NON STORE" operation. I was hoping it would
just
be something simple like a switch needing cleaning, or an IC needing
reseating, but nothing has given me any clues so far...
Colin.






Re: 2215 avoiding future CRT damage

 


So my CRT / filament is cooked then, by now, after nearly 40 years of use...
oh well... not much I can do about it, but at least if I find the trace too
dim at fast sweep speeds (haven't checked specifically for that yet), I will
know why and won't waste trying to "fix"/troubleshoot something that just
can't be cured ! :-(
At the time we had a simple procedure at our Field Office to determine
if the CRT should be replaced or not. I don't recall if it was an official procedure
or something we came up locally. We set the T/B to the fastest sweep speed with
X10 Magnifier, Hold Off to max, Auto Trig and no input signal. If the trace could
be seen with Intensity set to max , even just quite dim, the CRT was considered OK.

/Håkan

7A13 Comparison Voltage coarse knob

Colin Herbert
 

I have a later model 7A13 with the LED volts readout. It has the serial # 104748 and was made in Guernsey. It works fine, but the Comparison Voltage coarse knob is not the correct one. Would anyone have one of these to spare? Being where they are located, they are pretty vulnerable to damage and so may be a bit rare (hence the silly prices sometimes quoted). The Tek part number for the knob is 366-1084-00 and it just may be used on some other item of equipment. Reasonable costs understood.
TIA, Colin.

SC504 Gain Knob Removal

Larry McDavid
 

I have a SC504 scope module with a damaged Channel 1 knob skirt and I have a Tek replacement skirted knob. I can remove the small red central knob by loosening a set screw.

How is the skirted knob removed? I've tried gently pulling on it without success. The knob has a long plastic shaft with some internal ribs to fit over another shaft but I don't know how the knob is attached.

Anyone done this?

--
Best wishes,

Larry McDavid W6FUB
Anaheim, California (SE of Los Angeles, near Disneyland)

Re: 2215 avoiding future CRT damage

Vincent Trouilliez
 

On Fri, Jul 6, 2018 at 11:08 am, zenith5106 wrote:
We set the T/B to the fastest sweep speed with
X10 Magnifier, Hold Off to max, Auto Trig and no input signal. If the trace
could be seen with Intensity set to max , even just quite dim, the CRT was
considered OK.
OK... just perform said test, here is the result :

https://groups.io/g/TekScopes/photo/62323/0?p=Name,,,20,1,0,0

I adjusted the ISO setting of the camera so that the brightness on the pic actually matches the brightness level that my eyes perceive.
That's under normal conditions : a couple fluorescent tubes above the bench for lightning, and me sitting right in front of the scope, at a close but reasonable distance, I mean I did glue my face to the screen...

Looks like an "acceptable" tube then ? I mean it's very difficult to see, and any dimmer than this, would make it invisible but... as you say, you can still see the trace.

Plus, if I turn the var hold-off to the min, brightness comes back to normal, the trace becomes perfectly visible, no effort needed whatsoever.

I will admit I don't really master the var hold-off feature, I am not sure I get why it impacts the brightness level.. but obviously it does. Will need to do some reading and experimenting ! ^^

Anyway, looks like my CRT is not worn out in the end, what do you say ? That's good ! :-)
I mean I have sooo many problems left to fix on this scope, I really didn't need yet another (costly ! ) problem on my list ! LOL


Regards,


Vincent Trouilliez