Date   
Re: TDS 500 600 700 series calibration

Stephen Hanselman
 

I keep wondering about the actual use of the NVRAM on the control PCA in these scopes. I have been extracting the NVRAMS and reading them so I have a fair selection on the dumps. I have run the units without the NVRAM (except the ones that have the Timekeeper/NVRAM and they seem to function fine. However I have moved an initialized(cold start) Acquisition pca between units and the "initialized" status follows the Acq pca. I wonder if the cal data is really stored in the NVRAM. From looking at the dumps it looks to be used mostly for storing screen grabs.

Having said that I could be way off base

Regards,

Stephen Hanselman
Datagate Systems, LLC
3107 North Deer Run Road #24
Carson City, Nevada, 89701
(775) 882-5117 office
(775) 720-6020 mobile
s.hanselman@...
www.datagatesystems.com
a Service Disabled, Veteran Owned Small Business
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-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of Dan Fish
Sent: Sunday, February 3, 2019 8:56 PM
To: TekScopes@groups.io
Subject: [TekScopes] TDS 500 600 700 series calibration

I used to calibrate the 500MHz scopes but got rid of the AT PC and GPIB card. Still have the TM500 series plugins in the equipment list. Recently bought a TDS 584 (1GHz) with a bad display, crinkled gel between color shutter and front glass. Fixed that by removing gel. Found I could pull a length of wire (jacketed) between the layers to separate for cleaning. After display fixed found that a previous owner had thrown #3 dip switch to skip processor tests at turn on. This masks the calibration failure due to Dallas NVROM battery run down. So I have a nice pristine 1GHz DSO brick. I do have ability to copy the NVROM and put in a fresh one.

Does anyone know if the calibration procedure and equipment list for the 1GHz scopes is the same as the one I am familiar with for the 500 MHz scopes? I need to make a decision to gear up again for calibration or just put it up for sale.

Thanks, Dan

Re: Inappropriate language

Dave Daniel
 

Dennis,

Thank you.

Dave

Sent from a small flat thingy

On Feb 4, 2019, at 13:07, Dennis Tillman W7PF <@Dennis_Tillman_W7PF> wrote:

Our archives are readable by members of the general public. Recently a
message was posted with inappropriate language that is not a reflection of
the other 7,500 members of TekScopes. The individual who posted this message
was warned previously about similar posts but did it anyway.



I have taken the extraordinary step of deleting his message from the
archives, and removing this members posting privileges and daily summaries.
Additional messages by other members that quote or refer directly to the
language in the original post will also be deleted from the archives.



TekScopes Group Description is:

"All about classic Tektronix test equipment, its use, repair, and
collecting."



This would be a good time to remind everyone of what TekScopes is not about.
Inappropriate language and posts about the following topics were best stated
by Stefan Trethan who said it better than I could:



"No politics, no religion, no sports, simple as that. This has been the
golden rule for groups for a long time, because it works."



My apologies go out to all of the TekScopes members who received the
original post before it could be removed from our site.



Dennis Tillman W7PF







Re: 46x Analogue Storage Calibration

Fabio Trevisan
 

Hello Colin,
I won't be able to help you, but I join you in your frustration.
While trying to calibrate my 464, I had exactly same feelings and frustration about the instructions (and by just looking to the samples you given, it seems the instructions for the 464 were very similar to yours).
My 464's CRT was clearly worn-out so, at some point I realized I would never be able to get the Fast storage up "to spec" so I eventually gave up. Eventually I adjusted it the best that I could and gave it to a friend of mine.
Like you, I also noticed a gross mismatch between the pre-adjustments that were asked for the Front Mesh and Fast prep, and the final adjustments that can get you to a minimally operating Var Persistence mode.
When you start fiddling with the adjustments... (and only a few of them are relevant to the Var Persistent mode, which limits drastically the number of possible combinations), soon enough you realize that that the only possible settings to those adjustments to get the Var Persistence working at least minimally, completely disagree to the initial settings, so.... couldn't ever understand the rational of it all.

Back then I also asked for advice from anyone in the group who had practical experience on calibrating those beasts, and no heads up...Seem like not much people is familiar with this calibration procedure.

Since my CRT was so worn out, I was never able to tell if all the disagreements I was seeing was because the CRT was way off the specs... or if I just couldn't get the instructions right...

That's not to say your CRT is worn out... I suppose that if yours is so worn-out as mine was, you would know it "on-the-spot". On mine, trace was very dim at 50ns/div, and if I would use at 5ns (x10 engaged), I could only see the trace under complete darkness (and yet, quite dim).
So, if your CRT is not worn out, and you're still seeing the same inconsistencies that I saw during calibration, it probably means that either both our scopes share a similar defect, or that the instructions really don't make sense.

I wish I could help you more (by comparation of results) but I don't have the scope anymore.

Rgrds,

Fabio

Re: TDS 500 600 700 series calibration

 

On Mon, Feb 4, 2019 at 07:25 PM, Stephen Hanselman wrote:


I wonder if the cal data is really stored in the NVRAM. From looking at the
dumps it looks to be used mostly for storing screen grabs.
As far as I know they are in flash ROM on the Acq board and other than screen grabs
(or Waveforms) the NVRAM also contains stored settings.

/Håkan

Re: TDS 500 600 700 series calibration

Dan Fish
 

Hakan,

Consistent with the self-test complaining about cal if you mix boards between units. I do know the NVRAM holds purchased options. When I used to calibrate 520s and 540s I would pull the NVRAM, copy it into a fresh Dallas part, reinstall it, and then run the cal. Now I wonder if I was wasting my time. But I do recall a NVRAM location you can edit and turn on the FFT.

Do you know what part fails when you get the CalFails?

Thanks,
Dan

-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of zenith5106
Sent: Monday, February 4, 2019 2:35 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] TDS 500 600 700 series calibration

On Mon, Feb 4, 2019 at 07:25 PM, Stephen Hanselman wrote:


I wonder if the cal data is really stored in the NVRAM. From looking
at the dumps it looks to be used mostly for storing screen grabs.
As far as I know they are in flash ROM on the Acq board and other than screen grabs (or Waveforms) the NVRAM also contains stored settings.

/Håkan

Re: TDS 500 600 700 series calibration

Roy Thistle
 

Hi Dan:
I have a TDS540, that has not been powered up in a couple of years (maybe more!).
When I look from the side, in the right light, I can see some crazing or some wrinkling on at least the top half of the screen (looks like the surface of the plastic, in front of the crt screen, has been damaged by cleaning with a solvent; but, its not the plastic... it's below the plastic.).
Given what I am seeing, I am assuming it is the gel that has degraded?
Regards
Roy

Re: TDS 500 600 700 series calibration

Dan Fish
 

Roy,

Yes, I agree, this is common. You'll see it in pictures on ebay. Some have been happy with removing the gel, some not. I think it helps with light transmission and parallax. But you can remove it as long as your tube still has some life in it. But that is a problem with these scopes with the color shutters, they turn up the tube intensity to get through the shutters and the tube life is shortened.

If you try this, get the tube out. All along the front edge of the black sealant you can peel it back to see the edge of the glass and the start of the layers of the shutters behind. Don't go further than you need to. Just expose the gap between glass and shutters, avoiding the small gauge wires running around the shutters.

Once you see the gap you will see that the edge is sealed with RTV, yellowish white. That's the hard part because you have to pry with tools/blade to pick it out to expose the gel. Once most of the RTV is gone you can get the gel to separate and get the glass off. I did it with a couple feet of 18AWG insulated wire. Start at a corner in a sawing motion until you pull through. The glass should come off easily, don't force it, I broke the first one I tried.

It's a bit of a nasty clean-up to get the gel gone. I didn't try a strong solvent like acetone, although tempted. A good 99% alcohol and plastic scraper gets it. Then put the glass back on using the same gap. There will be enough nubs of RTV to set the gap. I sealed it up with a bead of black RTV.

Good luck!
Dan

-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of Roy Thistle
Sent: Monday, February 4, 2019 5:16 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] TDS 500 600 700 series calibration

Hi Dan:
I have a TDS540, that has not been powered up in a couple of years (maybe more!).
When I look from the side, in the right light, I can see some crazing or some wrinkling on at least the top half of the screen (looks like the surface of the plastic, in front of the crt screen, has been damaged by cleaning with a solvent; but, its not the plastic... it's below the plastic.).
Given what I am seeing, I am assuming it is the gel that has degraded?
Regards
Roy

7S12 TDR/Samper for sale

John Corini
 

Hello

Before I post this to E-bay, I thought that offer this for sale here. I have a 7S12 TDR/Sampler, with an S-52 Pulse head, S-1 and S-2 sampler heads for sale. I will include GR to BNC adapter. I would like $200 for the set, photos can be available on request.

Please contact me at ke1ih@...

Thanks

Re: TDS 500 600 700 series calibration

Harvey White
 

On Mon, 04 Feb 2019 17:15:34 -0800, you wrote:

Hi Dan:
I have a TDS540, that has not been powered up in a couple of years (maybe more!).
When I look from the side, in the right light, I can see some crazing or some wrinkling on at least the top half of the screen (looks like the surface of the plastic, in front of the crt screen, has been damaged by cleaning with a solvent; but, its not the plastic... it's below the plastic.).
Given what I am seeing, I am assuming it is the gel that has degraded?
The 540 is a monochrome output, and has no "gel".

The 544 has the LCD shutter, and therefore, the gel.

Harvey


Regards
Roy


Re: TDS 500 600 700 series calibration

 

It's a bit of a nasty clean-up to get the gel gone. I didn't try a strong solvent like acetone, although tempted. A good 99% alcohol and plastic scraper gets it. Then put the glass back on using the same gap. There will be enough nubs of RTV to set the gap. I sealed it up with a bead of black RTV.
I've found that Goo Gone (and how appropriate that name is!) works great on dissolving that gel. Just scrape off the majority with a soft plastic scraper first.

Jay

Best practices for working on a ceramic hybrid front-end board (TDS3032)

benj3867
 

Hi,

As the saga of fixing my TDS3032 continues, I am now faced with the need to remove one of the relays from the ceramic board/hybrid front-end module of channel 1 in order to gain access to one of the laser-trimmed resistors printed underneath it on the ceramic substrate.

My question is:
what is the best way to desolder and re-solder the relay (as well as how to eventually replace the blown printed resistor) without causing the pads printed on the ceramic substrate to disintegrate and disappear?

So please guys, share your experience and best practices for reworking these ceramic hybrids!

My own experience can be summarized as follows.
The ceramic strips used in tube-era Tektronix instruments are not the subject of this post. Indeed, following the recommended use of silver bearing solder I have never had any problem with these. However, the one time I have worked on a modern ceramic hybrid was different. I had to replace an op-amp on an LEM current sensor, and desoldering this DIP-8 chip using a desoldering braid removed about 30% of the pads material printed on the ceramic substrate as well. After soldering the new chip in (using silver bearing solder), and removing it one more time (don't ask why I had to do that :-)) two of the 8 pads were completely gone from the ceramic substrate. Unlike a regular epoxy PCB where pads may delaminate if one applies too much heat, her the pads were simply slowly disappearing together with the removed solder.

I have no idea if the ceramic hybrid used in the TDS3032 front-end (and many other modern Tek scopes) are more robust than the LEM hybrid I have worked on, but I would hate to find out that they are the hard way.

Wanted: knurled nut for earth terminal on 7K scope

 

The earth terminal at the right hand end of the centre section of the front
panel on the 4 bay 'scopes is threaded, and there's a knurled nut that
screws onto it. Part number is 200-0103-00.

I'm missing one - does anyone (ideally in UK/EU) have a spare one?

Thanks
David

Re: Best practices for working on a ceramic hybrid front-end board (TDS3032)

Brendan
 

On Tue, Feb 5, 2019 at 04:14 AM, benj3867 wrote:


Hi,

As the saga of fixing my TDS3032 continues, I am now faced with the need to
remove one of the relays from the ceramic board/hybrid front-end module of
channel 1 in order to gain access to one of the laser-trimmed resistors
printed underneath it on the ceramic substrate.

My question is:
what is the best way to desolder and re-solder the relay (as well as how to
eventually replace the blown printed resistor) without causing the pads
printed on the ceramic substrate to disintegrate and disappear?

So please guys, share your experience and best practices for reworking these
ceramic hybrids!

My own experience can be summarized as follows.
The ceramic strips used in tube-era Tektronix instruments are not the subject
of this post. Indeed, following the recommended use of silver bearing solder I
have never had any problem with these. However, the one time I have worked on
a modern ceramic hybrid was different. I had to replace an op-amp on an LEM
current sensor, and desoldering this DIP-8 chip using a desoldering braid
removed about 30% of the pads material printed on the ceramic substrate as
well. After soldering the new chip in (using silver bearing solder), and
removing it one more time (don't ask why I had to do that :-)) two of the 8
pads were completely gone from the ceramic substrate. Unlike a regular epoxy
PCB where pads may delaminate if one applies too much heat, her the pads were
simply slowly disappearing together with the removed solder.

I have no idea if the ceramic hybrid used in the TDS3032 front-end (and many
other modern Tek scopes) are more robust than the LEM hybrid I have worked on,
but I would hate to find out that they are the hard way.
On my TDS320 I cut the leads and ordered a new relay from Mouser. For the TDS320 the relays were under $2

Re: 7A26 attenuator compensation problem

Fabio Trevisan
 

On Mon, Jan 28, 2019 at 06:16 PM, Nenad Filipovic wrote:

Thank you all for your hints, but still no go.
Yes, 10mV and 20mV are pass-through...
Hello Nenad,
Arrived a little bit later to this, but I see there might be a confusion or misunderstanding that can ruin all the process down the road.
I do own a 7A26 myself and 10 and 20mV ARE NOT the ranges where all the high impedance attenuators are BYPASSED.
They're 5mV and 10mV / div, being that 10mV/div is the attenuation that shares the same preamplifier GAIN with all the other (higher) attenuation factors, while the 5mV/div setting stands alone on its own, as it employs no input attenuation (just as the 10mV does) and doubles the gain of the pre-amplifier.
If you're performing the preamplifier's LF and HF response adjustments at 10mV/div you're fine but, if you're performing them using the 20mV range, believing this range is a BYPASS range, then you will be compensating on the preamplifier's AC response adjustments, whatever deviation your X2 attenuator block might have, and this is not right.

So - risking to digress from Tektronix a little bit - basically what you would want is:
1. Go through the checks of the DC attenuation factors, to rule-out that there might be some bad contacts on the attenuator blocks and/or the contact leaves.
2. Using a low impedance source (e.g. going through a 50 Ohm past-through terminator), and using the 10mV range, perform all the preamp AC adjustments (LF and HF step response).
3. Changing over from the 50Ohm terminator to the Input normalizer, adjust the pre-amlipfier's input capacitance (C130 alone or C130 and C134, depending on the serial number of your 7A26).
4. Then perform each attenuator block's Frequency compensations and Input capacitances in the following order:

Re: 7A26 attenuator compensation problem

Fabio Trevisan
 

Apologies to everyone, I sent the message before finishing... Resuming now:

On Mon, Jan 28, 2019 at 06:16 PM, Nenad Filipovic wrote:

Thank you all for your hints, but still no go.
Yes, 10mV and 20mV are pass-through...
Hello Nenad,
Arrived a little bit later to this, but I see there might be a confusion or misunderstanding that can ruin all the process down the road.
I do own a 7A26 myself and 10 and 20mV ARE NOT the ranges where all the high impedance attenuators are BYPASSED.
They're 5mV and 10mV / div, being that 10mV/div is the attenuation that shares the same preamplifier GAIN with all the other (higher) attenuation factors, while the 5mV/div setting stands alone on its own, as it employs no input attenuation (just as the 10mV does) and doubles the gain of the pre-amplifier.
If you're performing the preamplifier's LF and HF response adjustments at 10mV/div you're fine but, if you're performing them using the 20mV range, believing this range is a BYPASS range, then you will be compensating on the preamplifier's AC response adjustments, whatever deviation your X2 attenuator block might have, and this is not right.

So - risking to digress from Tektronix a little bit - basically what you would want is:
1. Go through the checks of the DC attenuation factors, to rule-out that there might be some bad contacts on the attenuator blocks and/or the contact leaves.
2. Using a low impedance source (e.g. going through a 50 Ohm past-through terminator), and using the 10mV range (and not the 5mV range in my opinion), perform all the preamp AC adjustments (LF and HF step response).
3. Changing over from the 50Ohm terminator to the 1M Input normalizer, adjust the pre-amlipfier's input capacitance (C130 alone or C130 and C134, depending on the serial number of your 7A26).
4. Then perform each attenuator block's Frequency compensations and Input capacitances in the following order:
4a. Change from 1M Input normalizer to 50Ohm terminator, Set range to 20mV, Set generator's amplitude accordinglly, adjust C106 (this is x2 att.'s freq. compensation).
4b, Change from 50Ohm term. to 1M Input normalizer, leave everything else untouched, adjust C107 (this is x2 att's input capacitance).
4c. Change from 1M Input normalizer to 50Ohm terminator, Set range to 50mV, Set generator's amplitude accordinglly, adjust C110 (this is x5 att.'s freq. compensation).
4d, Change from 50Ohm term. to 1M Input normalizer, leave everything else untouched, adjust C111 (this is x5 att's input capacitance).
4e. Change from 1M Input normalizer to 50Ohm terminator, Set range to 100mV, Set generator's amplitude accordinglly, adjust C114 (this is 1st x10 att.'s freq. compensation).
4f, Change from 50Ohm term. to 1M Input normalizer, leave everything else untouched, adjust C115 (this is 1st x10 att's input capacitance).
4g. Change from 1M Input normalizer to 50Ohm terminator, Set range to 1V, Set generator's amplitude accordinglly, adjust C118 (this is 2nd x10 att.'s freq. compensation).
4h, Change from 50Ohm term. to 1M Input normalizer, leave everything else untouched, adjust C119 (this is 2nd x10 att's input capacitance).

Some might disagree from me, about keeping changing over between 50Ohm terminator and 1M Input normalizer, but the net result is the same, and by doing the frequency compensation adjustments always from a low impedance source, helps preventing that the input capacitance from the block being adjusted (which is not yet calibrated up to each step) will interfere in the compensation adjustment itself, even if it's grossly off.

Of course that this method implies that your generator is capable of sourcing at least 10Vpp on 1M load, and 5Vpp on 50Ohm (for an optimal 5 div display at 1V/div).

Doing this way has always yielded predictable results for me.

Rgrds,

Fabio

Re: Inappropriate language

Dale H. Cook
 

At 01:07 PM 2/4/2019, Dennis Tillman wrote:

Recently a message was posted with inappropriate language that is not a reflection of the other 7,500 members of TekScopes.
Dennis -

Thank you. Civility in public conversation is steadily coming to resemble the dodo. It is good to see that it is still the norm in TekScopes.

Dale H. Cook, GR/HP/Tek Collector, Roanoke/Lynchburg, VA
https://plymouthcolony.net/starcity/radios/index.html

Re: 7854 - yet another problem

Fred S.
 

The 7854 I'm trying to resurrect has a problem where the readout starts to
flicker a lot after it has been on for a short while.

Hi David,
if you store a waveform, is it flickering as well? I had a similar problem with the -15V supply on my 7854. It showed OK DC values by got ripple after a short time running. It was a 330uF filter cap in the powersupply.

--
Best regards,

Fred S.

Re: Wanted: knurled nut for earth terminal on 7K scope

 

Hi David,
I have one I can spare.
It shouldn't cost more than a few dollars to send it to you.
Keep me in mind if you can't find one locally.
Dennis

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of David
C.
Partridge
Sent: Tuesday, February 05, 2019 4:11 AM
To: TekScopes <Tekscopes@groups.io>; TekScopes2@groups.io
Subject: [TekScopes] Wanted: knurled nut for earth terminal on 7K scope

The earth terminal at the right hand end of the centre section of the
front
panel on the 4 bay 'scopes is threaded, and there's a knurled nut that
screws onto it. Part number is 200-0103-00.

I'm missing one - does anyone (ideally in UK/EU) have a spare one?

Thanks
David
--
Dennis Tillman W7PF
TekScopes Moderator

Re: 7854 - yet another problem

 

The problem was simple once it got bad enough that I could hear the crackle/hiss of EHT leakage - I removed the CRT (easier said than done), thoroughly cleaned the cable and around the seal where it connected to the PDA mesh (even though there was little if any sign of carbon tracking), and put it back together. Since then (so far) it has behaved perfectly .

PS I think the "real time clock" problem may have been related as it hasn't recurred. I think the real time clock refers to a problem with the "50Hz" signal from the Readout Acquire circuit (schematic <31>). Strangely the actual frequency in this scope was close to 70Hz (even though the timing R & C connected to pin 6 of U2510 were pretty much spot on value). Strangely U2510 isn't shown in the parts list for the Display Board (A29).
It's a 155-0021-01 timing generator and swapping it with one from another readout board made no change.

David

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of fred@...
Sent: 05 February 2019 15:21
To: TekScopes@groups.io
Subject: Re: [TekScopes] 7854 - yet another problem

The 7854 I'm trying to resurrect has a problem where the readout starts to
flicker a lot after it has been on for a short while.

Hi David,
if you store a waveform, is it flickering as well? I had a similar problem with the -15V supply on my 7854. It showed OK DC values by got ripple after a short time running. It was a 330uF filter cap in the powersupply.
--
Best regards,

Fred S.

Portable scope Tek /Sony.

vaclav_sal <vaclav_sal@...>
 

I like to replace my broken 464 with a small portable scope made by Tek and I believe with Sony.
About 40 years plus ago.
Do not remember the number , but it was two channel scope with attached probes , and same  hardware format as a multimeter they made.
I think it was battery operated , but not sure.