Date   

Re: Tek 22XX Fans

Jared Cabot
 

I've uploaded two images detailing how I added a fan into my 2235. As Leo mentioned, it's just a couple of components to add.
It should be roughly equivalent for other 22xx models too.

https://groups.io/g/TekScopes/album?id=263941


Re: 547 Recap

J
 

Harvey,

I was looking at the schematic and noticed that when I shorted the cases of (Q1074 and Q1084) it was just testing the common mode of everything to the vertical deflection plates. I do get a trace nominally, so I wasn't convinced that there was anything wrong with the parts in the vertical amp. Once I short the cases, that is when I get all of the deflection. Hence my doubling back to focus on the power supplies since the 100V rail exhibited 200mV of noise during the short. Your point is well taken however, that the load really shouldn't change much. Problem is, I can't think of what could be wrong in the downstream circuit - particularly because I'm getting a reasonable scope trace when I'm just using a plugin to drive the input.

Perhaps more testing is in order before moving forward.

Jerome


Re: 547 Recap

Brenda
 

On Sun, May 9, 2021 at 07:31 PM, J wrote:


I was going to focus on the electrolytics for sure. I was also thinking about
replacing them in sections rather than one at a time. Do the power supply
inputs first, The power supply output second, then the plug-in caps. Based on
your recommendation I may wait for the timing caps after working with them a
bit. Thank you.
Hi Jerome,

Harvey is right that Tektronix scopes do not like ripple. In fact, a lot of problems is due to the power supply issues. Just my 2 cents, replace one can electrolytic at a time. Some can be a single value while others will have multiple values. Doing 1 can at a time may seem like that it will take longer, but if there's a problem, will be much easier to troubleshoot. But yeah, go through the manual and the manual will tell you the max allowed ripple. If it's close to max, I would replace so you don't have to go back in a later time.

As far as timing capacitors goes, these are made by Tektronix in house and these are still superior compared to new capacitors. I am still learning about electronics and I have a few timing capacitors from Tektronix scopes that were beyond repair that still so accurate, it puts the new capacitors to shame as tolerance goes.

I do hope that this is helpful. And I would love to see that 547 come back to life again!

Brenda


Re: 547 Recap

J
 

I was going to focus on the electrolytics for sure. I was also thinking about replacing them in sections rather than one at a time. Do the power supply inputs first, The power supply output second, then the plug-in caps. Based on your recommendation I may wait for the timing caps after working with them a bit. Thank you.


Re: Manual for a Telequipment S61?

Liam Perkins
 

I forgot to say I need .tif format scanned files using LZW compression;
-not- .jpg-s and -not- .png-s; both of which are lossy compression formats
that produce artifacting I can't re-upsample to remove. Can't put the
toothpaste back in the tube, even with a funnel. Apologies for the
oversight.

On Sun, May 9, 2021 at 1:43 PM Liam Perkins via groups.io <hifi=
telus.net@groups.io> wrote:

All Right ! Fabulous.
May I trouble you to scan greyscale at 300dpi, that way I can make a proper
PDF of it and supply to those who've requested a copy, as well as to the
TekWiki. Done that way the scans will be good sized but ought to .zip down
to something you can e-mail to me at 'sales -at -pearl-hifi -dot - com'
were I can handle inbounds to about 25MB each. Maybe break it up into
several e-mails if needed.
TIA for the time and effort.
BTW, my request for pricing from this guy
http://www.servicemanuals.plus.com/index.html just bounced.

On Sun, May 9, 2021 at 1:33 PM Tom Lee <tomlee@ee.stanford.edu> wrote:

Hi Håkan,

I'd be interested in at least the schematics, as well, so if you do get
around to scanning them, I would appreciate a copy. I'm sure Kurt at
tekwiki would gladly receive them as well.

-- Tack så mycket,
Tom

--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
http://www-smirc.stanford.edu

On 5/9/2021 12:18, zenith5106 wrote:
On Sun, May 9, 2021 at 09:10 PM, Liam Perkins wrote:

I can't find a manual for a Tele' S61 anywhere and the TekWiki
download
link provides a manual for the D61A. Any suggestions
I have the right S61 manual. If you still want it I can have it scanned
by tomorrow.

/Håkan














Re: Problems with t935a HV supply

Ham Radio
 

Again, thank you all that replied. I will disconnect all the windings from the transformer and rerun the tests.

Is a 10 volt 1000 Hz square wave with a duty cycle of 1 % the proper frequency to do this type of ring test? My Tek scope using external trigger can easily display the results using the above mentioned parameters.

Mr Google told me that shorting a secondary winding on a transformer with a good primary (using a ring test) should reduce the damped oscillations by roughly 50%

This is certainly a learning experience.



--
Regards,
Bernie Murphy


Re: 547 Recap

Harvey White
 

I can't help you with some of these things, but perhaps I can tell you what you're doing in some of this.

The deflection plates of a CRT should (for various reasons) be driven in push pull.  That is, if you have a signal at the input of the amplifier, it should produce two signals, one going plus, one going minus.  This gives you effectively twice the sensitivity of the case where you hold one plate fixed, and feed a signal to the other.

Somewhere in the horizontal or vertical amplifier chain, you have a single signal.  There's a circuit that produces a positive going and a negative going signal from one signal.  The vertical or horizontal amplifier amplifies each signal and drives each plate from that resultant signal.  You have one chain doing a positive signal, one doing a negative signal.

If you were to short the deflection plates of the CRT, then if the geometry is right, the spot ought to be in the middle (either H or V) depending on what you shorted.

A useful technique is to go from the plates back and short the equivalent signal - to +.  If you don't get a display where the dot is exactly in the middle, then the amplifier is not giving you the same signal + and -, and you may have a bad component.

Anything you get where the signal is synchronous to the line generally indicates either ac line leakage to the amplifier, or bad power supply ripple.

Shorting two  transistors' collectors in this differential amplifier doesn't really increase the load, it just makes the + and - channel signals identical.

Proper working of a scope says that not only are the power supply voltages within tolerance, but the ripple is, as well.

Nasty things happen with ripple.

Harvey

On 5/9/2021 7:42 PM, J via groups.io wrote:
I have a 547 that I'm thinking about recapping. But I have a few questions before I start working on this, as I was having trouble finding info in the search function on the website.

I was attempting to recalibrate the scope when I got to step 9d. on the vertical amplifier: "Short the cases of Q1074 and Q1084 (see figure 5-4) together (not to ground) and note the trace deviation from electrical center. Deviation should not be more than 0.5cm maximum. Remove the short."

When I performed this step, I had about 7cm of deflection peak-to-peak (about 3 to 4cm from electrical center), and was asynchronous to the line. I started suspecting that it was a problem with the power supply, and I measured the peak-to-peak voltage to be about 200mV on the +100V rail when the collectors of these transistors were short. I reasoned that shorting the transistor collectors increased the load, and caused additional noise on the power supplies. And as a result, I found 200mV ripple on the power supply spec (exceeding the 15mV specification), so I need to at least find the culprit capacitors, and possibly recap the unit.

I then started looking at the locations of all of the power supply caps within the 547 and realized the mounted ones generally have more than one internal cap, and were mounted in ways that were very difficult (impossible?) to remove the mounted capacitors - under the parts on the ceramic terminal strops. The mounted capacitors were all 35mm in diameter.

Questions:
* If I order caps that are still 35mm in diameter, can I use the same mounting fixtures?
* How do I gain access to all these capacitors without disassembling the entire housing?
* If I recap the timing caps while I'm doing this - what voltage rating should I use? It's not specified in the parts list.
* I'm counting about 15 capacitors with lethal voltages on them - not sure I want them dangling around in the chassis. How have others gone about mounting them securely?
* I've thought about just leaving the original caps and adding the new caps where I can find good locations in the chassis. This isn't very clean though, but I'm still curious if others have had success with this approach.

Jerome





Re: GPIB board for calibrating AM503B, or alternatives?

 

Hi Rico,
Since Tek did not provide any support information in the manual for the AM503B I was hoping you found out even more about the internals than this little bit of information.
I am also very interested in knowing exactly how you did this so I can replicate the procedure.
Dennis

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Rico Sonderegger
Sent: Sunday, May 09, 2021 6:47 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] GPIB board for calibrating AM503B, or alternatives?

Hi Jared,

I have 3 of these GPIB adapters (have 3 x AM5030B).
I wanted to program the serial number and it didn't work. So I connected a logic analyzer to see what was going on.
If you only want to update the calibration data, you can use the addresses 0xE0-00xE1 (CALC 00 or RinX1 value), 0x0B-0X0C (CALC 01 or RinX10 value) and 0xCA-0xCB (CALC 02 or RinX100 value) on the I2C bus to program the new values in the PCF8570 (base address 0XA0) using a "Bus Pirate".
The calibration data are stored there. After changing the battery, there is 0x61A8 (= 25000).

Best regards
Rico







--
Dennis Tillman W7pF
TekScopes Moderator


Re: GPIB board for calibrating AM503B, or alternatives?

Jared Cabot
 

Oh, cool. Thanks for that. I guess I'll have to get onto learning how to use a Bus Pirate now, unless you want to sell one of your 5030B's (or swap for a 503B :D haha )

Can you provide any more specific info to help me out? I'm not much of a firmware guy.... Even just where to hook the Bus Pirate up and a basic idea how to send commands would be greatly appreciated.


Thanks for the info!


Re: 547 Recap

Brenda
 

Hello Jerome,

If you are thinking about recapping this, I would just focus on the electrolytics first but of coarse that is just my opinion. Tek 547 scopes are newer and I have never opened one up before but I am pretty sure that these use quite a but of disc caps which rarely goes bad. I could be very wrong, but I do know that they would not have the crappy bumblebee caps. As far as the timing caps goes, I would NOT recommend changing those out. I think there was an older thread that those rarely go bad and changing them generally created headaches. I have a 535A with the original timing caps and they are doing very well. I would also suggest to change 1 electrolytic capacitor at a time to make sure that things are going good. Changing them all at once and if something happens, you would be giving yourself more troubleshooting to do.

Brenda


Re: Problems with t935a HV supply

Tom Lee
 

Your intuition is spot on. If it passes an in-circuit test, that's usually reliable and you can stop there. If it fails an in-circuit test, it's hard to draw a reliable conclusion, so you have to free its terminals and re-test.

-- Cheers,
Tom

--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
http://www-smirc.stanford.edu

On 5/9/2021 16:39, Michael W. Lynch via groups.io wrote:
On Sun, May 9, 2021 at 05:21 PM, Tom Lee wrote:

As with resistance measurements, loading by other elements connected to the
DUT can confound results, so the only clean way to do a ring test is to
disconnect the transformer's windings from everything. There's no harm in
performing a ring test in circuit, but you can get false indications of a
problem. If it passes an in-circuit ring test, you can generally assume that
the transformer is ok.
Tom,

OK, that was what my mind kept telling me. It seems best to test components out of circuit, or at least that has been my experience. Since I have never done this sort of test before, I was assuming that removal of the component would be. preferred


547 Recap

J
 

I have a 547 that I'm thinking about recapping. But I have a few questions before I start working on this, as I was having trouble finding info in the search function on the website.

I was attempting to recalibrate the scope when I got to step 9d. on the vertical amplifier: "Short the cases of Q1074 and Q1084 (see figure 5-4) together (not to ground) and note the trace deviation from electrical center. Deviation should not be more than 0.5cm maximum. Remove the short."

When I performed this step, I had about 7cm of deflection peak-to-peak (about 3 to 4cm from electrical center), and was asynchronous to the line. I started suspecting that it was a problem with the power supply, and I measured the peak-to-peak voltage to be about 200mV on the +100V rail when the collectors of these transistors were short. I reasoned that shorting the transistor collectors increased the load, and caused additional noise on the power supplies. And as a result, I found 200mV ripple on the power supply spec (exceeding the 15mV specification), so I need to at least find the culprit capacitors, and possibly recap the unit.

I then started looking at the locations of all of the power supply caps within the 547 and realized the mounted ones generally have more than one internal cap, and were mounted in ways that were very difficult (impossible?) to remove the mounted capacitors - under the parts on the ceramic terminal strops. The mounted capacitors were all 35mm in diameter.

Questions:
* If I order caps that are still 35mm in diameter, can I use the same mounting fixtures?
* How do I gain access to all these capacitors without disassembling the entire housing?
* If I recap the timing caps while I'm doing this - what voltage rating should I use? It's not specified in the parts list.
* I'm counting about 15 capacitors with lethal voltages on them - not sure I want them dangling around in the chassis. How have others gone about mounting them securely?
* I've thought about just leaving the original caps and adding the new caps where I can find good locations in the chassis. This isn't very clean though, but I'm still curious if others have had success with this approach.

Jerome


Re: Problems with t935a HV supply

Michael W. Lynch
 

On Sun, May 9, 2021 at 05:21 PM, Tom Lee wrote:


As with resistance measurements, loading by other elements connected to the
DUT can confound results, so the only clean way to do a ring test is to
disconnect the transformer's windings from everything. There's no harm in
performing a ring test in circuit, but you can get false indications of a
problem. If it passes an in-circuit ring test, you can generally assume that
the transformer is ok.
Tom,

OK, that was what my mind kept telling me. It seems best to test components out of circuit, or at least that has been my experience. Since I have never done this sort of test before, I was assuming that removal of the component would be. preferred

--
Michael Lynch
Dardanelle, AR


vintage 531 in MN looking for new home

Chris Elmquist
 

A friend has a 531 (s/n 15xx) with 53B plug-in that needs a new home.

It's currently in his dad's basement here in MN, where it has been for
some 50 yrs. It has a Remington Rand cal sticker on it from a very
long time ago. It's a little dirty but otherwise undamaged.

No cart but probes are in the vicinity, yet to be found.

If interested, contact Richard at "sven.richard@gmail.com".

I don't know any particulars of a deal-- just helping him get the word
out to potentially interested parties so this heirloom does not get
trashed.

Chris
--
Chris Elmquist NØJCF


Re: Problems with t935a HV supply

Tom Lee
 

As with resistance measurements, loading by other elements connected to the DUT can confound results, so the only clean way to do a ring test is to disconnect the transformer's windings from everything. There's no harm in performing a ring test in circuit, but you can get false indications of a problem. If it passes an in-circuit ring test, you can generally assume that the transformer is ok.

--Cheers,
Tom

--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
http://www-smirc.stanford.edu

On 5/9/2021 15:06, Michael W. Lynch via groups.io wrote:
On Sun, May 9, 2021 at 05:02 PM, Harvey White wrote:

Perform the test with a dead short across one winding, and vary the windings
that you try this with.  It may not necessarily be bad.  Depends on the
loading on the winding, I think.

Harvey
All:

Can this Ringing test be done "in circuit" or does the DUT need to be removed from the board?


Re: 577 D2 question(s)

Chris Elmquist
 

On Friday (05/07/2021 at 09:29PM -0500), Andy Warner wrote:
Thanks for the pointers to 5110 scopes having the same tube. I was lucky
enough to have a friend of a friend who had a late model unit gathering
dust.
Hey! I resemble that remark.

I swapped the tube, and now have beautiful, crisp, bright traces.
We're just lucky I could remember where it was I had seen one of those
5100-series units.

I agree with Eric that this is a far nobler use for the tube than in a
low-spec 'scope.

Greatly appreciate the advice and suggestions.
And I am happy to know where a nicely working 577 is now not far away ;-)

Chris

--
Chris Elmquist


Re: Problems with t935a HV supply

Michael W. Lynch
 

On Sun, May 9, 2021 at 05:02 PM, Harvey White wrote:


Perform the test with a dead short across one winding, and vary the windings
that you try this with.  It may not necessarily be bad.  Depends on the
loading on the winding, I think.

Harvey
All:

Can this Ringing test be done "in circuit" or does the DUT need to be removed from the board?

--
Michael Lynch
Dardanelle, AR


Re: Problems with t935a HV supply

Harvey White
 

Perform the test with a dead short across one winding, and vary the windings that you try this with.  It may not necessarily be bad.  Depends on the loading on the winding, I think.

Harvey

On 5/9/2021 5:20 PM, Ham Radio wrote:
Thank you to all that replied. The resistance checks validate what Micheal reported.

My ringing tests on the primary indicate a lot of damping and not what Leo eluded in the posted pictures.

The ringing test on the feedback winding, indicate a much lower amplitude but the ringing is there.

The test were done with a 1000 Hz square wave with a duty cycle of 1% and an amplitude of 10 volts.

I have posted two scope pictures in the VE3FWF folder in the Photos section showing the results of these tests.

So I guess the HV transformer defective and the T922 becomes a parts mule ...






Re: Problems with t935a HV supply

Ham Radio
 

Thank you to all that replied. The resistance checks validate what Micheal reported.

My ringing tests on the primary indicate a lot of damping and not what Leo eluded in the posted pictures.

The ringing test on the feedback winding, indicate a much lower amplitude but the ringing is there.

The test were done with a 1000 Hz square wave with a duty cycle of 1% and an amplitude of 10 volts.

I have posted two scope pictures in the VE3FWF folder in the Photos section showing the results of these tests.

So I guess the HV transformer defective and the T922 becomes a parts mule ...






--
Regards,
Bernie Murphy


Re: Manual for a Telequipment S61?

Liam Perkins
 

All Right ! Fabulous.
May I trouble you to scan greyscale at 300dpi, that way I can make a proper
PDF of it and supply to those who've requested a copy, as well as to the
TekWiki. Done that way the scans will be good sized but ought to .zip down
to something you can e-mail to me at 'sales -at -pearl-hifi -dot - com'
were I can handle inbounds to about 25MB each. Maybe break it up into
several e-mails if needed.
TIA for the time and effort.
BTW, my request for pricing from this guy
http://www.servicemanuals.plus.com/index.html just bounced.

On Sun, May 9, 2021 at 1:33 PM Tom Lee <tomlee@ee.stanford.edu> wrote:

Hi Håkan,

I'd be interested in at least the schematics, as well, so if you do get
around to scanning them, I would appreciate a copy. I'm sure Kurt at
tekwiki would gladly receive them as well.

-- Tack så mycket,
Tom

--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
http://www-smirc.stanford.edu

On 5/9/2021 12:18, zenith5106 wrote:
On Sun, May 9, 2021 at 09:10 PM, Liam Perkins wrote:

I can't find a manual for a Tele' S61 anywhere and the TekWiki download
link provides a manual for the D61A. Any suggestions
I have the right S61 manual. If you still want it I can have it scanned
by tomorrow.

/Håkan









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