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That worked for me also.
Thank you very much!

Hi all.

I'm currently repairing my TM500 module TG501A which seems to have been dropped on its face in a previous life, and I need to repair the 100ohm potentiometer inside as the rod connecting the knob to the pot has damaged the switch section of the pot when it was slammed inwards during the unscheduled impact test.

Does anyone have a Tek part number 311-2351-00 potentiometer, or any other Clarostat brand pot that looks like the one in this photo?


I specifically need the 4-pin switch section at the rear to swap into my pot assembly, as these pots are modular and can have sections interchanged with the liberal use of a drill bit on the rivets holding them together to disassemble them, so the actual resistance value etc doesn't matter as long as it has the NO/NC switch section.

I have paypal funds standing by for anyone who can send a part to me in Japan.


Thanks!

Saw those and you are right, they are pricey critters.

Thanks, Dick, W1KSZ
________________________________
From: [email protected] <[email protected]> on behalf of Roy Morgan <k1lky68@...>
Sent: Friday, September 11, 2020 5:47 AM
To: [email protected] <[email protected]>
Subject: Re: [TekScopes] Test Fixture Name

Pomona Electronics has what you need. They are expensive but they are the best there is.

Not sure what they call them.

Roy Morgan
K1LKY Western Mass

On Sep 11, 2020, at 2:03 AM, John Gord via groups.io <johngord@...> wrote:

?Ed,
The Tek and Pomona boxes are similar (including color) but I don't think that Pomona made the Tek boxes.

...

The Pomona boxes have a textured finish and connectors secured by 4 screws each.
-

Pomona Electronics has what you need. They are expensive but they are the best there is.

Not sure what they call them.

Roy Morgan
K1LKY Western Mass

On Sep 11, 2020, at 2:03 AM, John Gord via groups.io <johngord@...> wrote:

?Ed,
The Tek and Pomona boxes are similar (including color) but I don't think that Pomona made the Tek boxes.

...

The Pomona boxes have a textured finish and connectors secured by 4 screws each.
-

The cooler theory seems plausible. Assuming that the SL92104 and CCD321A are basically the same device, then whatever the leads are connected to is not part of the chip.

Thank you all for your response. I have actually learnt a lot from your responses than from the article itself. It think this group is full of big brain and am happy am here. I will be consulting with most of you before writing any future article. Thank you all once again.
Carl

On Fri, Sep 11, 2020 at 08:02 AM, John Gord wrote:

The Tek boxes usually have a smooth finish and have connectors secured with a
mounting nut and a setscrew (the setscrew prevents the connector body from
rotating).

The Tek boxes were also available as blank boxes with only connectors, P/N 011-0081-00.
Both connectors are secured with set screws, no nuts.
/H?kan

Ed,
The Tek and Pomona boxes are similar (including color) but I don't think that Pomona made the Tek boxes. The Tek boxes usually have a smooth finish and have connectors secured with a mounting nut and a setscrew (the setscrew prevents the connector body from rotating). The Pomona boxes have a textured finish and connectors secured by 4 screws each.
--John Gord

The various Tek accessories and other parts were made by and branded Tek, but I'm pretty sure Pomona made (and still makes) the actual cast boxes, for many decades. These boxes are very common and used in many brands. Ed

Hi Siggi,

Thank you for your useful comments. The is a 2445 scope and not 2445A or 2445B.

I believe the scope has lost calibration data. The scope shows a failure of Test 04. With a status of 11. Having a look at the service manual just now I have found the following comment "If the bottom row of the readout contains dots in the normally blank spaces, a wrong calibration constant has been encountered. The instrument must be readjusted to remove the incorrect calibration constant from the EAROM". This matches exactly with what I am seeing on the CRT.

My suspicion is that the hybrid is working however I wanted to be sure as the start of the “A” sweep is off the CRT to the left. I am assuming that if the horizontal hybrid had failed then everything would have been to the left.

The scope does seem to trigger. The Trigged LED illuminates when the Cal signal is applied and trigger level adjusted.

Can the loss of the calibration constants result in the “A” sweep being “lost”?

Thanks,

Chris

Hey Christopher(?),

inline.

Siggi

On Tue, Sep 8, 2020 at 9:59 PM <christopherbath@...> wrote:

I am having issues with a 2445 Oscilloscope that is not showing the A
horizontal sweep.

This is a base 2445 as opposed to 2445A or 2445B?

The “B” sweep appears when the B delayed time base is used. The readout
shows some dots on the bottom line of text on the CRT. And the A sweep
appears to have a starting dot which is offset to the left of the CRT.

You may need to post a picture of what you're seeing on the CRT, and don't
forget to show the front panel control settings. You'll need to create a
new album in photos (/g/TekScopes/photos) and please link
the new album from your post.

I had wondered if the 2445 has issues with the horizontal output hybrid
(as the “A” sweep is offset to the left) or the Z-axis hybrid (as there are
dots on the CRT).

Depending on how this is manifesting, it could be that the dots are
signifying that the scope has lost calibration. Does it go through power up
self-tests at power-up, or do you need to press a button before you get to
sweeps?

As the “B” sweep and readout appears however this seems to imply that the
horizontal output hybrid may be working?

If you get a readouts and/or a sweep, that'd indicate your
horizontal/vertical output hybrids are working.

I am not sure is there could be a failure mode of the horizontal output
hybrid which results in the “A” sweep not appearing.

You've verified that triggering works? More likely than an output hybrid
would be a trigger or some kind of a control problem.

I have swapped the “A” and “B” sweep hybrids which did not resolve the
issue.

I have tested the "A+" input to U800 and whilst there is a large DC offset there is no AC component.

That's what they look like, but definitely branded Tektronix.

Another List Member gave me the right name ... RC Input
Normalizer.

Thanks, Dick, W1KSZ
________________________________
From: [email protected] <[email protected]> on behalf of satbeginner <castellcorunas@...>
Sent: Thursday, September 10, 2020 11:19 AM
To: [email protected] <[email protected]>
Subject: Re: [TekScopes] Test Fixture Name

Pomona maybe?

Thanks, lots of good suggestions. The IR imaging camera sounds really helpful, have to look into getting one.
What I ended up doing was to separate the 15VPS from all the loads, and coincidently, or maybe not, there was one of those white-insulated jumpers proximate to the last PS component, C173x?, 15uF?EC. Pulled the jumper, and, voila, got 15.0 volts. Expected the other side to be still near shorted, but oddly it was now reading about 50 ohms. Huh? Reinstalled the jumper, with series ammeter, and voltage holding steady at 15.0 with 0.75A current. Buttoned everything back up.
How could pulling the jumper have "fixed" the problem? I'm stumped.
Note: my other 466 had a bridge of white powdery material, like the stuff on battery posts, between this same cap (C173x?) at the output of the 15VPS and the adjacent 65V test point. Thinking it likely came from the EC leaking over the years... Cleaned it up, and working fine now, too (both CH traces would get unfocused intermittently...).
Alls well that ends...so far. Not overly confident, as nothing was replaced.

Question: there was mention of multi-layer pc boards. Did TEK use more than a 2-layer board (top and bottom traces) in this generation of scopes?

On Thu, Sep 10, 2020 at 09:52 PM, Clark Foley wrote:

I have posted the Fairchild data sheet to this site as a File
(Fairchild_CCD_VideoDelayLine_PossilbleSL92104.pdf).

/g/TekScopes/files/Fairchild_CCD_VideoDelayLine_PossilbleSL92104.pdf

Raymond

Richard,

I found what I believe to be the same part. The pins and functions are the same, but under a different part number. I don't remember if Tek had them screened or selected for critical specification. The commercial Fairchild part number is CCD321A Analog Video Delay Line. I have posted the Fairchild data sheet to this site as a File (Fairchild_CCD_VideoDelayLine_PossilbleSL92104.pdf). The file is 5Mbytes.

It is possible that the four wires might be supplying power to a pair of thermo-electric coolers (a.k.a. Peltier coolers or reverse Seebeck). This is my guess without seeing what is actually attached to the ICs. I would have to pester one of the designers to confirm.

Clark

On Wed, Sep 9, 2020 at 8:32 PM Vince Vielhaber <vev@...> wrote:

Ok, the problem has been solved!

Congrats!

As I mentioned before, I lifted one lead of both resistors (and a couple
of others) and they were all within spec. Strangely enough, it took
another 6.8K across R875 (a 6.19K) to drop pin 2 (inv) on U870 to 0.10V
less than pin 3. Measuring R875 again (with a lead lifted) it was
giving a new value.

How quaint, but I guess it happens. I had a problem in my 485 sweep
generator where a precision resistor went voltage dependent on me. Measured
up just fine on a DMM, but beat Ohms law handsomely at its working voltage
:/.

Pomona maybe?

That's the one. I need to find one or two to make DC Blocking Caps for my
pricey HP Sig Gens.

Thanks, Dick, W1KSZ
________________________________
From: [email protected] <[email protected]> on behalf of Colin Herbert via groups.io <colingherbert@...>
Sent: Thursday, September 10, 2020 11:16 AM
To: [email protected] <[email protected]>
Subject: Re: [TekScopes] Test Fixture Name

Hi Dick,
You may be thinking of the Tek Input RC Normalizers. They are cast metal
boxes with, as you say, a male BNC at one end and a female BNC at the other.
They contain in parallel, a (usually 1M) resistor, a fixed capacitor to suit
the capacitance of the input and a trimmer capacitor, accessible via a
plastic plug on one side. Access is made through a plate held in place by
four screws. Does that sound like it?
Colin.

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Dick
Sent: 10 September 2020 19:04
To: [email protected]
Subject: [TekScopes] Test Fixture Name

I am looking for one of these small boxes (around 1" X 1" X 2-3")
that had a Male BNC on one end and a Female BNC on the other
end.

Tektronix made them probably 40 to 60 years ago.

What would be a correct name to do a search on ?? Small Box
just doesn't get there !!

Thanks, Dick, W1KSZ