1. TekScopes@groups.io
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Re: 2440 nvram (was: NVRAM back-up battery change on a 2715..... avoiding disasters)

Raymond Domp Frank
 

On Sat, Nov 9, 2019 at 08:39 PM, Szabolcs Szigeti wrote:


I think what the SM says here is when you press the button, it recalculates some values and
writes it to the nvram.
Quite likely.

But this needs to be done after every change in setting the pots.
True for the operational settings, not true for the Adjustment (chapter 5) data that is stored in the "store..." menus during Adjustment.

So for the original question of is there a real need to save the 2440 nvram
when _it is in cal_ but the nvram needs to be changed, the answer is no, as
the scope can be brought back to calibrated state by running the self cal and ext cal.
Here I disagree.
If this were true, what purpose would the menu-supported adjustments (like setting numbers, turning external pots) and storing by pressing keys etc., see msg #161473, during manual calibration ("Adjustment", chapter 5) serve? They are quite different from the saving of operational settings, which happen all the time during use.
In these respects, the NVRAM function is quite comparable to that in 'scopes like the 2445/65 series. Calibration constants are stored in NVRAM, as are the operational settings. The latter change all the time when working with the 'scope, whereas the former cannot be restored by just pressing a button: The scope needs to be Adjusted as per SM chapter 5. Many 'scopes also store user-initiated attenuator offset corrections in NVRAM.

...the scope can be brought back to calibrated state by running the self cal and ext cal.
Not if the constants that were set during Adjustment (chapter 5) were lost because of exchanging the NVRAM , unless the 'scope does have another place to store them. It seems that we don't know where that would be in this model.

Raymond
7854 power supply disassembly

Alberto, IZ2EWV
 

Hello friends,
The 7854 that I recently bought, after some minutes of operation started emitting a whistle, a burst, some smoke from the rear ad an awful burning smell... "as usual!" I thought, remembering the past experience with my 7904A, in which the problem was in the AC filter. But here the bad component is the RC snubber C5 in the A23 switching board.
The problem is: how to disassemble the A23 board from the A12? I tried to unscrew the A12 from the chassis and the rear heatsink, hoping that it could come with the transformer, but some wires of the latter are soldered to the A23 board!
Anybody could explain to me the easier way to separate the two boards? I would like to avoid to make disasters, considered that I have to replace only one component! And the wires of the transformer and the other coils are leaving me afraid.
I'm not the kind of who cuts the bad part and solders the new one by the component side of the board, or simply bypasses it, so I need to know how at Tektronix they service this board.
Thank you in advance,
Alberto, IZ2EWV
Re: Trade P6137 for P6139A probes

Jean-Paul
 

Dear Manuel, I may be able to do it, but am traveling away from the lab for a while.

If you can wait till early or mid December remind me with private message and I will check my inventory.

How many 6137 are available and how many 6139A do you want?

Are you located in USA?

Best Regards

Jon
Re: 7S14 7S11 SAMPLER bias QUESTION

Raymond Domp Frank
 

On Sat, Nov 9, 2019 at 06:23 PM, Miguel Work wrote:


Question is why 7S11 works without cells, and 7s14 need it. And if is possible
to use 7s14 with the same scheme. 7s11 uses +-50 v to bias sampling bridge.
I guess the following is relevant: The samplers as used in the 7S11 need much sharper/shorter strobe pulses and a special physical layout to achieve the much higher bandwidth and the battery circuits are incompatible with that. Remember that the 7S14 is made for a much lower bandwidth (1 GHz) than the 7S11, which goes up to 14 GHz with an S4 sampler.
In the circuit diagram of the 7S11 the sampler is shown as a rather simple thing but what you see there is only a block diagram because samplers (the plugins) are each different. Looking at the diagrams of any of the sampler plugins, you'll see that they in fact are rather complicated beasts. By comparison, the 7S14 is much simpler, being "LF" by comparison.
So, it probably more a matter of the 7S14 "getting away with" the much simpler battery biasing scheme.

Raymond
Re: 2440 nvram (was: NVRAM back-up battery change on a 2715..... avoiding disasters)

Szabolcs Szigeti
 

Hi,

No, there is no other writable store in the instrument what i know about,
and there doesn't seem to be any on the schematics. I think what the SM
says here is when you press the button, it recalculates some values and
writes it to the nvram. But this needs to be done after every change in
setting the pots. So for the original question of is there a real need to
save the 2440 nvram when _it is in cal_ but the nvram needs to be changed,
the answer is no, as the scope can be brought back to calibrated state by
running the self cal and ext cal. This does not need any physical setting
inside the scope (well except for the cal enable jumper). If the scope is
out of spec (which an old one most likely will be), then the answer is no
again, because you have to do the full adjustment procedure anyway.
However, I'm no authority on this, I did do calibration on a number of
2440s and experimented with them too, but I don't know how the firmware
actually works. Would be interesting to reverse engineer though, as there
are a number of really cryptic features in the calibration menus, about
which the Sm doesn't say a word.

Szabolcs


Raymond Domp Frank <hewpatek@gmail.com> ezt írta (időpont: 2019. nov. 8.,
P, 17:30):

On Fri, Nov 8, 2019 at 02:45 PM, Szabolcs Szigeti wrote:


But these are all adjustments requiring turning trimmer pots.
I had a quick look in the SM. The Adjustments chapter (5) mentions e.g. on
pages 5-8 and 5-10 (in my manual) "WRITE TO CAL STORE" and on page 5-13
"Pushing A HORIZONTAL MODE causes the instrument to make firmware
corrections...".
I assumed that those writes and corrections were to the NVRAM. If you're
right, the 2440 has yet another kind of "writable ROM" than the NVRAM. Do
you know if that's true and if so, what kind of storage it is?

Raymond
AWG 2021conversion from rackmount, looking for clues on parts.

Szabolcs Szigeti
 

Hi,

I scored a nice AWG 2021, in a rackmont setup. I had to do some metal
bending, as it was dropped at one time, but it is working now nicely and
has all the nice options of 2nd channel and the FFT editr.
Since I don't have a rack, and the rack part was damaged anyway, I want to
convert it back to a normal desktop instrument as it would fit under my
2440 with the Tekmate so it cando direct wafeorm transfer. I could figure
out the obvious things, like different length screws on the back, and
missing feet and hadle, but the floppy drive puzzles me a bit.
Looks like there is a completely different frame holding the connector for
the cable to use the floppy externally and also there is a different cover
plate. I know that the floppy is of little use nowadays and it is located
at a very inconvenient place on this instrument anyway, much better to use
it is now, brought to the front on a cable, but it bugs my OCD :-)
Would anyone have the instructions for the rack mount kit (Option 1R) so i
could see what needs to be changed or maybe take some photos. or have the
parts for sale :-)

Thanks a lot in advance.

Szabolcs
Re: 7S14 7S11 SAMPLER bias QUESTION

Miguel Work
 

Thanks for your answer Raymond,

I have studied 7S11 and 7S14 vertical blocs. Question is why 7S11 works without cells, and 7s14 need it. And if is possible to use 7s14 with the same scheme. 7s11 uses +-50 v to bias sampling bridge.

Regards

Miguel

-----Mensaje original-----
De: TekScopes@groups.io [mailto:TekScopes@groups.io] En nombre de Raymond Domp Frank
Enviado el: sábado, 9 de noviembre de 2019 16:44
Para: TekScopes@groups.io
Asunto: Re: [TekScopes] 7S14 7S11 SAMPLER bias QUESTION

On Sat, Nov 9, 2019 at 04:00 PM, Peter H wrote:


Take a look at http://w140.com/tekwiki/wiki/7S14/Repairs and the 7S14
circuit diagram.
You have to read the doc of the 7S11 and the sampling plugins as well.

Note that the 7S14 is a complete horizontal and vertical sampling unit and the 7S11 is just a vertical plugin for the 7000 series *without* its own sampler.
To make use of the 7S11, you need a sampler like an S-4 or S-6. Logically, the floating batteries of the 7S14 are in the samplers but the S-x 'es live without a floating battery supply.
Have a look here as well: http://w140.com/tekwiki/wiki/7S11

Raymond
Re: DPO7054 question about Edge button

Tam Hanna
 

Hello,

maybe this video helps you - soldering SMD leds, down to 0603 is doable. Just be careful not to "crush" the LED with the pincer when it is hot:

https://www.youtube.com/watch?v=FAuKQgwyQuk



--
With best regards
Tam HANNA

Enjoy electronics? Join 15k7 other followers by visiting the Crazy Electronics Lab at https://www.instagram.com/tam.hanna/
Re: 555 for sale in Maryland - $250 with cart and goodies

Mlynch001
 

Jamie,

Same here! I was trying to figure out a way to pick this up or make arrangements. I just cannot make it happen. This is a treasure trove of great stuff!

--
Michael Lynch
Dardanelle, AR
Re: 7S14 7S11 SAMPLER bias QUESTION

Raymond Domp Frank
 

On Sat, Nov 9, 2019 at 04:00 PM, Peter H wrote:


Take a look at http://w140.com/tekwiki/wiki/7S14/Repairs and the 7S14 circuit
diagram.
You have to read the doc of the 7S11 and the sampling plugins as well.

Note that the 7S14 is a complete horizontal and vertical sampling unit and the 7S11 is just a vertical plugin for the 7000 series *without* its own sampler.
To make use of the 7S11, you need a sampler like an S-4 or S-6. Logically, the floating batteries of the 7S14 are in the samplers but the S-x 'es live without a floating battery supply.
Have a look here as well: http://w140.com/tekwiki/wiki/7S11

Raymond
555 for sale in Maryland - $250 with cart and goodies

Jamie Ostrowski
 

It makes me so sad I but I simply can't afford to travel and buy this beautiful gem right now. I thought someone here might be interested:

https://www.facebook.com/marketplace/item/472746093502260/
Re: A few pics from a new-to-me exhibit in the National Museum of Nuclear Science and History

Glydeck
 

Dan,

You are correct. The 535 came from Stan Griffiths at the Vintage Tek museum in trade for a 570 they had. He said he tried to explain that Tektronix was a post war company and that any Tek scope would be an anachronism. The nuclear history museum said they understood but just needed something for the exhibit. BTW, the 570 is on display at the Vintage Tek museum.

George

On Nov 7, 2019, at 6:29 AM, Daniel Koller via Groups.Io <kaboomdk=yahoo.com@groups.io> wrote:

I'm no nuclear science history expert, but wrt the original post, that 535 seems out of place. The criticality experiments were generally carried out in the 1940's and the 5 series was not available till the 1950's. Afterall, by 1945 they knew what it took to make a pile of uranium go off.
But in the 1950's the techniques of Nuclear spectroscopy were being developed and that scope would have been at home reading the pulse outputs of scintilation counters. I used such scopes in Columbia University's undergraduate physics labs in the 1980's for just such pulse counting. they had not updated the labs in 30 years (!!) so it was very much like working in the 1950s
Someone correct me if I am wrong in my time estimates.
Dan

On Wednesday, November 6, 2019, 10:02:59 PM EST, <sdturne@q.com> wrote:

On Sat, Nov 2, 2019 at 01:10 AM, battyhugh wrote:


If you are in Minneapolis - on the S side of the bridge across the river on
the W side (if I remember correctly) - there is another relic - you have to
decend about 6 stories down - there are masses of HB spec analysers and a
rather large Van de Graffe generator - - very strange (I saw it in early 90's)
- A Dr Weiblen was working at that time on using high voltage pulses to bust
up moon rock. It would be rather interesting to document the remaining
residues of the 50's and 60's (on the marshes near Palo Alto is an old radio
transmission facility - might be interesting... but wait.. there's more!
Hmmm, is it an abandoned site or is someone taking care of it?
Re: vintageTEK scanned transformer drawings for 120-0998-01 and up

quadzillatech@...
 

is the 453a-1 transfo the same,ie the one in the hv compartment?,as mine is stuffed!,cheers Paul m3-vuv.
Re: 7S14 7S11 SAMPLER bias QUESTION

Peter H
 

Take a look at http://w140.com/tekwiki/wiki/7S14/Repairs and the 7S14 circuit diagram.
Re: NVRAM back-up battery change on a 2715..... avoiding disasters

Chuck Harris
 

Congratulations!

It will be the first of many.

-Chuck Harris

michele.trozzi@gmail.com wrote:

The cell voltage was 2.74 V, now it is 3.23 V.
I just successfully replaced.
I followed your advice, using a second cell soldered to pins 4-8 of DS1210.
My wife saw me during the work and told me: you put it in extracorporeal circulation. She is a nurse.
I had several heart strokes (pin removed from the original cell, positive battery terminal near gnd and the like) but I did it!
At the end I drank a large glass of red wine.
Next replacement scheduled for November 9, 2029.
Re: NVRAM back-up battery change on a 2715..... avoiding disasters

Michele Trozzi
 

The cell voltage was 2.74 V, now it is 3.23 V.
I just successfully replaced.
I followed your advice, using a second cell soldered to pins 4-8 of DS1210.
My wife saw me during the work and told me: you put it in extracorporeal circulation. She is a nurse.
I had several heart strokes (pin removed from the original cell, positive battery terminal near gnd and the like) but I did it!
At the end I drank a large glass of red wine.
Next replacement scheduled for November 9, 2029.
Re: NVRAM back-up battery change on a 2715..... avoiding disasters

Chuck Harris
 

What is the cell's voltage now?

-Chuck Harris

michele.trozzi@gmail.com wrote:

Reading the manual I have understood that after data loss in the NVRAM, you can do a simple re-calibration using the internal calibrator.
This can allow to make just qualitative measures. All linearization data must be re-entered with a complete calibration using very precise signal generator and power meter at different values of amplitude and frequency. This is necessary to get a good amplitude responce on the whole freq. range. The bad thing is that an elusive "271X Flatness Tests" original software is necessary to carry on this procedure.... and a working very old PC.
This is the reason why my hands are shaking to change a battery!
Siemens Hall Effect Motor Lubrication without total disassembly?

Bru H
 

Hi All,
A long time ago someone said it is possible to lubricate the Oilite Bearing if you place the motor in a vertical position and allow oil to seep into the shaft area.

I have not been into a Siemens Hall effect Motor to see if this would work. I have read Justine Yong's article and can see the internal view.
Can the Shaft protruding side be lubricated by keeping the unit upright and allowing oil to run down the shaft and into the plastic to get to the Oilite bearing?
Can the Set Screw be removed on the other side of the motor to get oil into this side?

Could this possibly be good maintenance?
Could this possibly do more damage by getting excess oil into the winding area?
Anyone try this, experience etc?

Thank you very much
Re: NVRAM back-up battery change on a 2715..... avoiding disasters

Michele Trozzi
 

On Fri, Nov 8, 2019 at 02:50 PM, Chuck Harris wrote:


I am not 100% on this instrument, but the 2710, and 2711 both
have the ability to fully calibrate themselves built into the
unit.

The 2715, which is specialized for Cable TV, probably has this
feature too.

All should be revealed in the manual.

-Chuck Harris

michele.trozzi@gmail.com wrote:
On the other hand, to recovery a possible parameter loss, I ask if someone
knows a procedure to upload the original parameters for this SA 271x family.

Reading the manual I have understood that after data loss in the NVRAM, you can do a simple re-calibration using the internal calibrator.
This can allow to make just qualitative measures. All linearization data must be re-entered with a complete calibration using very precise signal generator and power meter at different values of amplitude and frequency. This is necessary to get a good amplitude responce on the whole freq. range. The bad thing is that an elusive "271X Flatness Tests" original software is necessary to carry on this procedure.... and a working very old PC.
This is the reason why my hands are shaking to change a battery!
Re: Tek 485 short sweep

Mlynch001
 

I suggest that the HV Multiplier is bad. I had a 468 and a 475 that both had bad HV Multipliers (Both shorted). On my units with a shorted HV Multiplier. there was no trace until the service jumper was removed. The shorted multiplier was grounding the HV transformer and loading it to the point that no trace was produced, my -2450V was only about -300V. If the HV Multiplier has failed “open” instead of “shorted”, then the trace will be shorter than normal, regardless of the service jumper. An open HV multiplier will not load the HV transformer but the post deflection acceleration voltage will still not be there. On my particular units, Once the service jumper was removed, the short to ground was removed, my -2450V was restored and my trace came back, but in a shortened version, in either scenario there was no post deflection acceleration voltage. Replacing the HV Multiplier restored both units to a full trace. My 2 cents. I would love to hear any other ideas on this fault.
--
Michael Lynch
Dardanelle, AR
18261 - 18280 of 179679