Date   

Re: Binding Post Thumb/Head Nut Replacements

 

Renée,

The "originals" are the two "steel" finish nuts with diamond knurling on the bottom. The replacements are the black oxide finish and brass nuts on the top.

-- Jeff Dutky


Re: ++Processor error on TDS 754D on startup

BobH
 

Thanks for the information. The reason that I was asking is that I have been working on a replacement for the battery backed SRAMs. I currently have an 8Kx8 board design that I am testing. It does not support timekeeping right now. B
ackup power is supplied by a socketed coin cell on top of the board.

I looked at the two part numbers you supplied, the DS1486 has RAM and a clock on board, and is obsolete with 0 stock at Mouser. The DS1250Y is a 512Kx8 SRAM which would be more approachable for a homebrew fix, but they are still available with Mouser having them in stock. They are expensive though.

On the boards that I am working on, they are using the DIP package. I have been looking at adding timekeeping to my design, but that is going to get a lot more complex, as it will require an FPGA to allow formatting the data to emulate the various module part numbers. Also, 5V tolerant FPGAs are getting scarce.

Good Luck with your 754D, those are nice scopes!
BobH


Re: Looking for data on 9-pin Vacuum time delay relays used in old Tek-scopes

David Kuhn
 

" If you were building a replacement for one of these delay relays
(hypothetically speaking, maybe for a 533A), would it be enough to have a
timer that cut a relay in after a fixed time? Is that really all that the
delay relay is doing?"

If its filaments are in the heater chain, something would need to be done
to replace the filament of the time tube. Also, if it is in the heater
chain in a serial fashion (I don't think they are, eh? I have to study the
schematics again), that is a safety factor if one tube's filaments open,
that power does not get applied.

I am probably overthinking it. a 555 and a S202SE2 SS Relay would probably
suffice.

Dave

On Sun, Jul 18, 2021 at 11:06 PM Jeff Dutky <jeff.dutky@gmail.com> wrote:

Bruce,

If you were building a replacement for one of these delay relays
(hypothetically speaking, maybe for a 533A), would it be enough to have a
timer that cut a relay in after a fixed time? Is that really all that the
delay relay is doing?

Might there be another way to determine when the heaters are at
temperature, like by monitoring the current through the heaters, or even by
directly sensing the temperature of the tubes themselves?

Just curious (though I am in the process of refurbing a 533A, and this may
be useful information when I get to the point of applying power to the
instrument)

-- Jeff Dutky






Re: Looking for data on 9-pin Vacuum time delay relays used in old Tek-scopes

David Kuhn
 

" For instance https://frank.pocnet.net/sheets/084/6/6NO45T.pdf .
Albert"

Albert; thank you; I had been thinking of this too. In industrial
controls, we would use on-shot (Time Delayed) relays too, but they are much
larger and bulkier than that tube.

I guess someone could design a tiny 555 timer and relay to replace it if
needed. An extra aggravating (LOL) step, but yaa got ta do what yaa gotta
do.

Dave

On Sun, Jul 18, 2021 at 4:02 PM Albert Otten <aodiversen@concepts.nl> wrote:

For instance https://frank.pocnet.net/sheets/084/6/6NO45T.pdf .
Albert






Re: Binding Post Thumb/Head Nut Replacements

Renée
 

Jeff -
which are the originals and which are "new"?
Renée

On 7/19/21 4:53 AM, Jeff Dutky wrote:
I have added a photo album with pictures of the two replacements I have found compared to two sizes of thumb nuts from Tek instruments: https://groups.io/g/TekScopes/album?id=266234

I have also found another candidate in this item on eBay: https://www.ebay.com/itm/390837689359

I will post pictures when the parts arrive.

-- Jeff Dutky




Re: 2712 SA with display (and normalization) issues #photo-notice

Colin Herbert
 

Have you looked here?

https://w140.com/tekwiki/wiki/2712

Not OCR, but probably useful. Failing that, try Artek Manuals (http://artekmanuals.com/). They don't have it listed but they might be able to help.

Colin.

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Ronan
Sent: 18 July 2021 22:59
To: TekScopes@groups.io
Subject: Re: [TekScopes] 2712 SA with display (and normalization) issues #photo-notice

Just one more tidbit (before I decide if I'm going to dig deep into it).

Enabling debug diagnostics and re-running the Frequency Normalization indicates this:

“ERROR in MAIN DAC OFFSET: Cannot center start spur”

Explanation: "Beginning at 10 MHz/div span, the start spur was located and
centered, then span was reduced. In 1 MHz/div span, the signal
could not be centered within 30 horizontal storage bits."

I have a “oddity”, a +30dB rise of about 70MHz width:

https://ibb.co/db150Tr 1486 MHz
https://ibb.co/5BLWK3D 1498 MHz
https://ibb.co/xh3kybp 1558MHz

Does anyone have an OCR of the 2712 Service Manual?

Thank you
Ronan


Re: ++Processor error on TDS 754D on startup

pmoyle111
 

I believe the they are DS1486, and DS1250Y (from memory of reading recently) I guess maybe I should hunt the data sheets and re-familiarize myself with the beasts - I used to know something about everything Dallas had- but that was mid '90's. I started hoping I could find someone I could pay to do it and just outsource the problem, but it looks like I'm going to end up diving into the swamp.

I don't know which is the culprit but if one is replaced so should the other due to battery age, and pulling the board out and reworking one is not much less than reworking both.
I have seen on some threads, someone has designed a workalike using a non battery Dallas part allowing using an external battery
But at the moment I'm looking for assistance with how diagnose the problem further to prove that is the problem
I am getting in a Prologix IEE488 to usb adaptor in a week or so and I would like to get some instruction on how to download/upload the content
If it's one of those I should be able to clear the error at least long enough to do a self test to verify the hypothesis. I have a file someone posted for the DS1486 - I suppose that is where the error is

Anyhow just looking for some diagnostic steps I can go thru using 488 I/F. I have seen some using the floppy, but I don't have any of those and I guess you could find them online somewhere, but I think the 488 I/F will just be better, more user friendly, more robust


Re: 7904A compress sweep

Tom Phillips
 

Thanks for suggestions

I moved the gain pot slightly but it has little effect.

The power supply voltages are very close to spot on and stable but the four metal output transistors Q610, 20 30 and Q640 are definitely hot. I'm in the middle of a long distance move and don't have another scope handy at the moment to check stage waveforms but if needed are equivalents for motorola ST919/ST7394 available? Casual web search not turning up much.


Re: Binding Post Thumb/Head Nut Replacements

 

I have added a photo album with pictures of the two replacements I have found compared to two sizes of thumb nuts from Tek instruments: https://groups.io/g/TekScopes/album?id=266234

I have also found another candidate in this item on eBay: https://www.ebay.com/itm/390837689359

I will post pictures when the parts arrive.

-- Jeff Dutky


Re: Power transformer 453A

Fred Schumacher
 

Mark,
Thank you for the effort to inform me about the secundary voltages. I expected this already.
If I decide to use a 454 transformer, which is identical to a 453 transformer, I have to do some cable dressing, as these transformers are horizontally arranged, with respect to the 453a transformer which is vertically arranged.
Anyway thanks again for your info.
Fred

On 18 jul. 2021, at 18:20, Mark Vincent <orangeglowaudio@gmail.com> wrote:

Fred,

The voltages on the secondaries of mine with the input set on the high range at 120V mains input: Pins 21 and 22- 6,3V
Pins 12 and 13- 17,4V
Pins 10 and 11- 18,6V
Pins 13 and 15- 90V
Pins 16, 17, 18, 19 and 20- 71, 59, Gnd. 59 and 71V
With slight line variations, the voltages will vary slightly. Voltages were measured with the loads applied and the 6,3V with graticule set at minimum so the a-c voltage at these pins is higher than the nominal 6,3V. This is a 6,3V winding. I would guess the other power transformers you mentioned would work. The 454 type may have a heavier winding for the heaters in the older S/N types. That is fine. The only thing that may be the difference is the current and slight physical size difference. If you can get one, it should work fine.

Mark





Re: Looking for data on 9-pin Vacuum time delay relays used in old Tek-scopes

 

Bruce,

If you were building a replacement for one of these delay relays (hypothetically speaking, maybe for a 533A), would it be enough to have a timer that cut a relay in after a fixed time? Is that really all that the delay relay is doing?

Might there be another way to determine when the heaters are at temperature, like by monitoring the current through the heaters, or even by directly sensing the temperature of the tubes themselves?

Just curious (though I am in the process of refurbing a 533A, and this may be useful information when I get to the point of applying power to the instrument)

-- Jeff Dutky


Computer interface to 576

Paul Amaranth
 

I know folks have been talking about this for a while and it looks like
someone actually did it.

https://www.ebay.com/itm/303606230408?hash=item46b0576d88:g:U7kAAOSwghpe9UW-

Description is a bit on the thin side and if you're going to go to all that
trouble it seems that you should calculate the parameters instead of making
you calculate them off the screen grid. Apparently you do get cursors, meh.

Disclaimer: no connection to whoever did it
--
Paul Amaranth, GCIH | Manchester MI, USA
Aurora Group of Michigan, LLC | Security, Systems & Software
paul@AuroraGrp.Com | Unix/Linux - We don't do windows


Re: 2712 SA with display (and normalization) issues #photo-notice

Ronan
 

just one more thing...
yeah, right. It is pretty warm in my lab in Calif. today -- I attempted a full normalization just now, it succeeded. Perhaps this is more proof I need to do the real work now from great posts such as Mike/WZ5Q, Randy/AB9GO, Marcus/PP5MS (et al).

Now I'm thoroughly convinced I need to check PS voltages/ripple, and to order two batteries -- check the caps and do the due diligence. I am headed to the copy/print store to make printouts of the 11x17 schematics.

Appears surprisingly "normal": https://ibb.co/4f3jhKW

Thanks for your virtual patience,

R


Re: Looking for data on 9-pin Vacuum time delay relays used in old Tek-scopes

Ulf Kylenfall
 

Dear all,

I have received datasheets in PM's off the list and also links in this thread.

Thank you all!

Cheers

Ulf Kylenfall


Re: 2712 SA with display (and normalization) issues #photo-notice

Ronan
 

Just one more tidbit (before I decide if I'm going to dig deep into it).

Enabling debug diagnostics and re-running the Frequency Normalization indicates this:

“ERROR in MAIN DAC OFFSET: Cannot center start spur”

Explanation: "Beginning at 10 MHz/div span, the start spur was located and
centered, then span was reduced. In 1 MHz/div span, the signal
could not be centered within 30 horizontal storage bits."

I have a “oddity”, a +30dB rise of about 70MHz width:

https://ibb.co/db150Tr 1486 MHz
https://ibb.co/5BLWK3D 1498 MHz
https://ibb.co/xh3kybp 1558MHz

Does anyone have an OCR of the 2712 Service Manual?

Thank you
Ronan


2 files uploaded #file-notice

TekScopes@groups.io Notification <noreply@...>
 

The following files have been uploaded to the Files area of the TekScopes@groups.io group.

By: udtmang@...

Description:
Has some data on the Amperite relays


Re: Looking for data on 9-pin Vacuum time delay relays used in old Tek-scopes

 

Ulf,

I designed these into things about fifty years ago. The Amprite type numbers generally provided the data. For example a 117NO60 would indicate a 117-volt unit with normally-open contacts that would close 60-seconds after power was applied. These thermal delay relays were often used to delay the application of plate voltage until cathodes warmed up.

Bruce, KG6OJI


Re: Looking for data on 9-pin Vacuum time delay relays used in old Tek-scopes

stevenhorii
 

Sorry - I included a graphic of the pinout on my first reply, but I guess
it was blocked.

Here's the Web site that has it - along with a link to download a PDF.

https://amperite.com/35119-thermal-time-delay-relay/

Steve Horii

On Sun, Jul 18, 2021 at 3:37 PM ulf_r_k via groups.io <ulf_r_k=
yahoo.com@groups.io> wrote:

Dear forum,

I have been trying to find datasheets for the Amperite time delay relays
used in older Tek scopes. They are built in 9-pin tube glass envelopes.

Looked in w140.com but maybe not long enough to find any.

No hits by simply googling the type number...

Is there someone who knows where to find specs?

Cheers

Ulf Kylenfall
SM6GXV







Re: Looking for data on 9-pin Vacuum time delay relays used in old Tek-scopes

Albert Otten
 


Looking for data on 9-pin Vacuum time delay relays used in old Tek-scopes

Ulf Kylenfall
 

Dear forum,

I have been trying to find datasheets for the Amperite time delay relays
used in older Tek scopes. They are built in 9-pin tube glass envelopes.

Looked in w140.com but maybe not long enough to find any.

No hits by simply googling the type number...

Is there someone who knows where to find specs?

Cheers

Ulf Kylenfall
SM6GXV

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