Date   

Re: Stan Griffiths Book

Dave Brown
 

We have listed Oscilloscopes: Selecting and Restoring a Classic by Stan Griffiths in paperback on the museum's eBay store. We lowered the price from what these sold for previously and likewise decreased the price on the CD PDF version.
https://www.ebay.com/str/vintagetek


Re: Searching for a Tek 7000 series scope

Dave Seiter
 

Yesterday I went to a nearby estate sale that had a lot of interesting stuff, but one thing that stood out was a Tek 536 sitting on a K212 (or similar) scopemobile.  At first I thought it was sitting on an extended bench top;  I didn't want to even touch the thing, fearing it might collapse.  They wanted $150 for it (with two garden variety plugins).
-Dave

On Saturday, April 20, 2019, 7:15:59 PM PDT, Roy Thistle <roy.thistle@mail.utoronto.ca> wrote:

On Sat, Apr 20, 2019 at 06:39 PM, Dave Seiter wrote:


I have one of my 7704As on a K212 scopemobile,
Hi Dave:
We/I have to see a picture of that.
Scopemobiles are great for say for the likes of a 465 or a 2415... but a fully stuffed 7704?
Not saying it can't be done... but, can it be done for the nervous?
Best regards and wishes to all.
Roy


Re: WTB: used Tek 2467B SRAM module

n4buq
 

Curious: Typically, how inaccurate is a 24xx series scope that has a new NVRAM installed?

Thanks,
Barry - N4BUQ

The easiest solution is to simply install a new NVRAM, and to
let the scope install its default calibration constants, and to
let the scope warn you that it is out of calibration.

The Test04 Error can be dismissed by pressing the A/B Trigger
button, and the ????? marks on the display cause no harm to any
diagnostic work you may need to do to repair your scope.

In this condition you can do everything you can do with a scope
that is fully calibrated, but it won't be accurate.

And, you won't have a scope that is full of garbage calibration
constants, but looks like it is calibrated.

The only valid reason, in my opinion, to install the calibration
constants from another scope into your scope is to enable you to
fool some unsuspecting customer into thinking the scope you are
selling is calibrated.

You don't want to do that, do you?

-Chuck Harris


Re: Tek board found at flea market

 

On Sun, May 12, 2019 at 01:09 AM, Jeff Woolsey wrote:


Thus it appears to be from an R7844.
Almost off-topic: My very late (1991) R7844 has a readout board equipped with a microprocessor. The PCB layout looks early-days computer-generated. Narrow traces, sharp corners. The layout makes it look like a Philips product. Almost all IC's are Philips and the thing was made in Holland. If it looks like a duck and quacks like a duck, could it be...? Type id. 671-1342-02 and 389-0599-02. The mainframe itself was made in Beaverton (B162183). I still love the looks of the R7844.

Raymond


Re: Tek board found at flea market

Jeff Woolsey
 

On 5/11/19 4:09 PM, Jeff Woolsey wrote:
On 5/11/19 3:54 PM, Dave Brown wrote:
If you look it up in the 670- RPR on TekWiki it is used in a great number of products depending on the suffix. The -00 was used in the 7913/R and the 7904. The -01 was used in the 7313/R, 7603/R, 7613/R, 7623/R, and the 7633/R. There is also a -02, -03, -04, -05, and -06. There are too many instruments to list here.
I don't know if it's clear in the photo, but the suffix is a paper label
saying "06".  Thus it appears to be from an R7844.
And a bunch of other things.  First time reading that RPR...

--
Jeff Woolsey {{woolsey,jlw}@jlw,first.last@{gmail,jlw}}.com
Nature abhors straight antennas, clean lenses, and empty storage.
"Delete! Delete! OK!" -Dr. Bronner on disk space management
Card-sorting, Joel. -Crow on solitaire


Re: Tek board found at flea market

Jeff Woolsey
 

On 5/11/19 3:54 PM, Dave Brown wrote:
If you look it up in the 670- RPR on TekWiki it is used in a great number of products depending on the suffix. The -00 was used in the 7913/R and the 7904. The -01 was used in the 7313/R, 7603/R, 7613/R, 7623/R, and the 7633/R. There is also a -02, -03, -04, -05, and -06. There are too many instruments to list here.
I don't know if it's clear in the photo, but the suffix is a paper label
saying "06".  Thus it appears to be from an R7844.

--
Jeff Woolsey {{woolsey,jlw}@jlw,first.last@{gmail,jlw}}.com
Nature abhors straight antennas, clean lenses, and empty storage.
"Delete! Delete! OK!" -Dr. Bronner on disk space management
Card-sorting, Joel. -Crow on solitaire


Re: Tek board found at flea market

Dave Brown
 

If you look it up in the 670- RPR on TekWiki it is used in a great number of products depending on the suffix. The -00 was used in the 7913/R and the 7904. The -01 was used in the 7313/R, 7603/R, 7613/R, 7623/R, and the 7633/R. There is also a -02, -03, -04, -05, and -06. There are too many instruments to list here.


Re: Please, help me a fix my 2467B.

 

All boards have a calibration jumper, its called J501.  Not all scopes have a -1.25 test jumper called J504.  You have to look at your particular A5 board to see if you have one.  Its a convenience for testing, not a necessity.  By the way, coordination with us on Tekscopes will be much more reliable if we refer discussion to specific Tektronix defined identifiers.  So I refer to J504, not as the jumper that changes -1.25 Volts.
Since the problem seems to have gone away, I suggest you do the usual technical probing to see if something is loose, then give up until the problem returns.

On Saturday, May 11, 2019, 03:24:41 PM CDT, leandro.lindemann@terra.com.br <leandro.lindemann@terra.com.br> wrote:

Thank you for the valuable information. I do not replace any components so far. I only removed some to clean the board, looking for traces of acid that could have leaked from the capacitors next to the circuit. These capacitors I switched to about 2 years or less. My board has a calibration jumper, this is what you are referring to, correct?

I get nervous about working on this scope, it cost me hundreds of hours of work, here in Brazil I believe they are extremely rare and I got it from a person who brought it to me from the USA.

Should I then, when the defect happens again, make sure the value of the voltage of -1.25V, correct? As I said, I am not absolutely sure of this value, but absolute certainty that there was 1.46V oscillating at the 1.36V point when the fault occurred.


Re: Tektronix 7A13, application note?

 

Hi Steve,
I think both of your reasons don't stand up to the ample evidence to the contrary.

For instance, over the years Tek added additional features to the 7000 manuals to make these instruments more supportable and serviceable. As an example I can point you to the 7104 Service Manual which had many more helpful charts and photos in it when the 1989 revision was released than the earlier revisions of this manual.

The real changes in Tek's philosophy of supporting their products came in the late 1980s when management, in a desperate attempt at finding new ways to boost their flagging revenue, decided to make product support a "Profit Center". This reversed a fundamental cornerstone the company's reputation was built on. For almost 50 years Tek provided product support at no charge. Tek became the model for the rest of the electronics industry for their support.

The change was first apparent in the late 1980s when some new products were released with a shell of the former service manual. The manuals for these products, such as the 11,000 series, the AM503B, or the TVC501 TM500 instruments, no longer had schematics. If the product stopped working your only recourse was to return it to the factory for repair. After the product had been out for a few years even factory support was terminated. The purpose of factory repair was for Tek to reap the repair revenue for themselves (hence the "Profit Center" designation). The purpose of ending factory support was to force you to buy a new product to maximize Tek's revenue. Why keep repairing products for ever if they can make more money selling you a new improved product?

Anyone could see this approach was short sighted. But by that point senior management was no longer from the inside of the company. They were all outsiders more interested in short term gains and their own golden handcuffs than the reputation and the future of the company. This fundamental change in their support philisophy sped up the demise of Tek by making the competition from China and elsewhere even more attractive to buyers.

Dennis Tillman W7PF

-----Original Message-----
From: Stephen Hanselman
Sent: Friday, May 10, 2019 9:56 AM
Subject: Re: [TekScopes] Tektronix 7A13, application note?

I suspect two reasons, it was cheaper to do the manual but more importantly it was the beginning of the "change the board" rather than the "find the component" school of troubleshooting
steve

-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of unclebanjoman
Sent: Friday, May 10, 2019 9:01 AM
Subject: Re: [TekScopes] Tektronix 7A13, application note?

Hi all,
Just discovered that the manual for the early version of the 7A13 (mechanical counter) has more detailed operating instructions and some measurements examples.
I don't know why the latest manuals omits this.
Max



--
Dennis Tillman W7PF
TekScopes Moderator


Re: Tek board found at flea market

Rajesh VS
 

On Sat, May 11, 2019 at 1:28 PM Jeff Woolsey <jlw@jlw.com> wrote:

I found a 4"x4" board, (C) 1971 Tek, P/N 670-1900? All chips sockets, 3
TTL chips, remainder in-house. A row of 8, w/6 ascending part numbers wired
in parallel (like memory). Any idea what it is? Anyone need it? My guess
is a readout board.

See photos in album named same as subject.



--
/Rajesh


Tek board found at flea market

Jeff Woolsey
 

I found a 4"x4" board, (C) 1971 Tek, P/N 670-1900? All chips sockets, 3 TTL chips, remainder in-house. A row of 8, w/6 ascending part numbers wired in parallel (like memory). Any idea what it is? Anyone need it? My guess is a readout board.

See photos in album named same as subject.


Re: Please, help me a fix my 2467B.

Leandro Lindemann
 

Thank you for the valuable information. I do not replace any components so far. I only removed some to clean the board, looking for traces of acid that could have leaked from the capacitors next to the circuit. These capacitors I switched to about 2 years or less. My board has a calibration jumper, this is what you are referring to, correct?

I get nervous about working on this scope, it cost me hundreds of hours of work, here in Brazil I believe they are extremely rare and I got it from a person who brought it to me from the USA.

Should I then, when the defect happens again, make sure the value of the voltage of -1.25V, correct? As I said, I am not absolutely sure of this value, but absolute certainty that there was 1.46V oscillating at the 1.36V point when the fault occurred.


Re: Dirty 453 worth $5?

RustySparks
 

What about the HV transformer failure in so many 453 scopes? They seem to fail over time due to chemical changes in the potting material used on the transformer. I had to give up on repairing the 453 I have had since it was new because I couldn't come up with a replacement transformer (that wouldn't soon fail again simply because of its age).
A few here have rewound theirs with success, but I can't spend that much time on such a project.

-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of Brendan via Groups.Io
Sent: Saturday, May 11, 2019 1:14 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Dirty 453 worth $5?

One of the last tek scopes with no custom IC's so they can be repaired with off the shelf parts. For someone who does vintage audio work they are awesome. I have repaired many Sansui receivers with my 453. Also from what I have seen the prices are rising. I'm always looking for cheap 453 scopes and can't find them. The last ham fest I went to I picked up three 2430A's, two TDS320's and a TDS420 all for cheaper than the single working 453.

On Sat, May 11, 2019 at 08:54 AM, Scott Newell wrote:


Found a dirty 453 at a local estate sale. Covers off, might have been
rained on, looks like all the knobs and feet are present. Didn't see
anything obviously missing, smoked, or mis-repaired.

I don't need it and really don't have time to fix it, so I'm thinking
it's a parts unit (for me) at best. Unless y'all can convince me
otherwise... ;-)

So, if anyone in the US needs 453 parts cheap, speak up and I'll grab
it this evening. Otherwise I'll probably let it go.


--
newell N5TNL


Re: Please, help me a fix my 2467B.

Leandro Lindemann
 

Yesterday, as the defect manifested, I replaced this 15Uf capacitor with a 22uF capacitor because it was the value I had in the SMD package. It did not work. After that, I thought of using an external power supply set at 1.36V in parallel with the capacitor, but I was afraid.

Could you do this? I believe that if the defect does not manifest itself after this test, I will have isolated the sector that causes the defect.


Re: Please, help me a fix my 2467B.

 

Your DAC and its resistors are most certainly OK since the -1.25 is good.  The DAC generates -1.25 then an op amp uses that to generate +1.36.  Its very odd that +1.36 is in error but -1.25 is not.  So be absolutely certain.
Don't go changing any resistors right now or you will create more problems that it solves.  I used to repair TV's and know how expedient it is to repair the usual culprits and see if the problem clears up.  But this is a precision instrument and a single change in this area means a full recalibration of the entire scope.  TV's get their precision from syncing the incoming signal.  This scope gets its precision from the DAC and those resistors.  At any rate, they are R2012 and R2013, sometimes R2015 and the trimmer R2010.
Many A5 boards have a test jumper labeled J504.  If you move this jumper to connect pin 2 and 3 it will bypass the DAC and create -1.25 directly, bypassing those resistors and the DAC.  If you do this and +1.36 is still wrong we have zeroed in on a likely problem.

On Saturday, May 11, 2019, 02:02:48 PM CDT, leandro.lindemann@terra.com.br <leandro.lindemann@terra.com.br> wrote:

On Sat, May 11, 2019 at 11:53 AM, machineguy59 wrote:


Some questions.1. Does it happen on all four channels?2. Does it happen when
you ground the input signal (not connected to the calibrator).3. Do you have
another scope to watch the 1.36 voltage while this happens?  A DVM is
probably too slow to catch the precise timing of this noise.4. The 1.36 Volts
is derived from the -1.25 Volts.  Is the -1.25 Volts stable?
Your initial checks indicate the 1.36 Volts is incorrect and unstable.  This
makes me think the problem is on the A5 board, likely in the area of the
DAC.  Several resistors associated with the DAC are very sensitive to damage
from contaminations.
On Saturday, May 11, 2019, 01:15:32 PM CDT, Craig Cramb < @Manfromtrane (
/profile/Manfromtrane ) > wrote:
Yes, it happens on the 4 channels.
It happens even when the input of channels 1 and 2 is grounded.
It's my only scope. I use an old, multi-meter valve with high input impedance and realized with it the voltage variations of 1.36v, which yesterday was 1.46V (confirmed with a Fluke 189).
From what I remember yesterday, yes the -1.25V were correct and stable.
Please, can you tell me which are the suspect resistors? I would trade them all.


Re: Please, help me a fix my 2467B.

Chuck Harris <cfharris@...>
 

The 1.36V reference power supply is not very strong,
and it feeds directly an electrolytic capacitor. You
might want to try testing, or replacing that capacitor.

-Chuck Harris

leandro.lindemann@terra.com.br wrote:

Hello.

Throughout the day, the scope works wonderfully well (as it always did). The voltage at the 1.36V point is rock solid. Yesterday, when the deed was happening, I unhooked the cable that goes to the front plate and the defect continued to occur, which would disclose a defect in the keys.




Re: Picked up a 464 for $25, checkout and cleaning questions

Stephen Leander
 

Service manual is really nice and concise. I did read thru the part on cleaning solutions, they don't like anything with Freon in it (not really and issue these days), isopropyl alcohol is recommended for contacts it would appear. There is also a nice, full "checkout" procedure, I'll probably start there to identify any issues.

Any other recommendations welcome, new to this series of scope.


Re: Tek 213

Miguel Work
 

This scope draws few milliamps when is off, is normal, in this diagram paths are marked in orange arrows

https://groups.io/g/TekScopes/photo/90462/0?p=Created,,,20,2,0,0



-----Mensaje original-----
De: TekScopes@groups.io [mailto:TekScopes@groups.io] En nombre de oliver johnson via Groups.Io
Enviado el: viernes, 12 de octubre de 2018 1:07
Para: TekScopes@groups.io
Asunto: [TekScopes] Tek 213

I have put batteries into my tek 213 , i used 8 1200mah aa batteries series parallel to get my 2.4 volts . I was unsure of the capacity of the original d cells but i figured 4800mah should be more than enough , that being said scope worked fine and appeared to charge ok as well .

I charged for about 8 or so hours but when i powered scope nothing happned , i tried with plugging into outlet still nothing , so i opened up scope and checked battery voltage . As it turns out one group of cells were charged while the others were very low , i tried a different battery ,it powers on but not for long . I did also notice that when batteried were left in scope they would die in a day or so just being off .

Is it possible that i could have a bad cap that drained the scope even when powered off???, or is there another reason why this has happened . Now i can only get scope to power with Ac plug working , any thoughts ????


Re: Please, help me a fix my 2467B.

Leandro Lindemann
 

On Sat, May 11, 2019 at 11:53 AM, machineguy59 wrote:


Some questions.1. Does it happen on all four channels?2. Does it happen when
you ground the input signal (not connected to the calibrator).3. Do you have
another scope to watch the 1.36 voltage while this happens?  A DVM is
probably too slow to catch the precise timing of this noise.4. The 1.36 Volts
is derived from the -1.25 Volts.  Is the -1.25 Volts stable?
Your initial checks indicate the 1.36 Volts is incorrect and unstable.  This
makes me think the problem is on the A5 board, likely in the area of the
DAC.  Several resistors associated with the DAC are very sensitive to damage
from contaminations.
On Saturday, May 11, 2019, 01:15:32 PM CDT, Craig Cramb < @Manfromtrane (
/profile/Manfromtrane ) > wrote:
Yes, it happens on the 4 channels.
It happens even when the input of channels 1 and 2 is grounded.
It's my only scope. I use an old, multi-meter valve with high input impedance and realized with it the voltage variations of 1.36v, which yesterday was 1.46V (confirmed with a Fluke 189).
From what I remember yesterday, yes the -1.25V were correct and stable.
Please, can you tell me which are the suspect resistors? I would trade them all.


Re: Please, help me a fix my 2467B.

Leandro Lindemann
 

Hello.

Throughout the day, the scope works wonderfully well (as it always did). The voltage at the 1.36V point is rock solid. Yesterday, when the deed was happening, I unhooked the cable that goes to the front plate and the defect continued to occur, which would disclose a defect in the keys.

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