Date   

Re: Fw: You have been removed from TekScopes@groups.io

Richard Knoppow
 

This message came through the list so you seem to still be on it. I wonder if this is hacking of some sort. You can check if you are subscribed on the web site. I would not return anything until you are sure. I suspect there is a hidden URL in the Resume Subscription link. Most e-mail clients will tell you if there is. The whole message doesn't quite make sense so I suspect it is phishing of some sort and you will be asked for all sorts of personal info.

On 10/31/2020 12:48 PM, Thomas Dodge wrote:
Hi,
I don't know why I was removed. I saw the email message, but it was not
from me. Can you please resubscribe me? Thanks. Also, the link to
subscribe was not there. It was just the word, but no link.

Thomas Dodge

On Sat, Oct 31, 2020 at 10:38 AM Ken Wright via groups.io <kenwright309=
yahoo.co.uk@groups.io> wrote:

This is the message I receivedKen M0KHW ----- Forwarded message -----
From: TekScopes@groups.io <tekscopes+owner@groups.io>To: "
kenwright309@yahoo.co.uk" <kenwright309@yahoo.co.uk>Sent: Friday, 30
October 2020, 10:09:01 GMTSubject: You have been removed from
TekScopes@groups.io
Hello,
You have been automatically removed from TekScopes@groups.io because your
Email Service Provider reported to us that message Re: source for blue
filters for 2465 family scopes ??from TekScopes@groups.io has been marked
as spam.

We suggest that you check your spam folder as soon as possible to see if
your Email Service Provider has diverted other legitimate messages into it.

You will receive no more emails from that group. If this was a mistake,
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--
Richard Knoppow
dickburk@ix.netcom.com
WB6KBL


Re: Fw: You have been removed from TekScopes@groups.io

Thomas Dodge
 

Hi,
I don't know why I was removed. I saw the email message, but it was not
from me. Can you please resubscribe me? Thanks. Also, the link to
subscribe was not there. It was just the word, but no link.

Thomas Dodge

On Sat, Oct 31, 2020 at 10:38 AM Ken Wright via groups.io <kenwright309=
yahoo.co.uk@groups.io> wrote:

This is the message I receivedKen M0KHW ----- Forwarded message -----
From: TekScopes@groups.io <tekscopes+owner@groups.io>To: "
kenwright309@yahoo.co.uk" <kenwright309@yahoo.co.uk>Sent: Friday, 30
October 2020, 10:09:01 GMTSubject: You have been removed from
TekScopes@groups.io
Hello,
You have been automatically removed from TekScopes@groups.io because your
Email Service Provider reported to us that message Re: source for blue
filters for 2465 family scopes ??from TekScopes@groups.io has been marked
as spam.

We suggest that you check your spam folder as soon as possible to see if
your Email Service Provider has diverted other legitimate messages into it.

You will receive no more emails from that group. If this was a mistake,
you can resume your subscription within the next 7 days by clicking the
following link:

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The Groups.io Team







Filament Isolation Transformer

Robert Simpson
 

Chuck,

Since this is more of a general topic, I thought it might be better in a separate message.
This topic came out of a different subject related to safely using an oscilloscope to look at home generator output. Chuck Harris suggest using a filament transformer to isolate the scope from the generator. This technique could be used in many applications.

Previous related messages:

---------
Filament transformers are cheaper than a repair on your scope's
front end, and will reveal everything that matters on your
generator's output signal.

A second thing about instrumentation. When you are measuring
stiff power sources, you need to take stiff protection measures.
When you are measuring weak power sources, weak protection
measures will suffice.

Your generator is a fairly stiff power source. It can dump
way more than 4000W into a dead short circuit.
---------
I think I have a 120 to 12V transformer. So I might try some tests with motor loads, such as my table saw and hand electric saw.
Question, should the output leads of the transformer be open or have a light load say 10K oms?
Bob
-----------
I usually just leave the 1M scope load to set the
output impedance.

But, since it is easy, try a few different values,
and see what looks the best.

50 ohms would not be a good idea, as it would draw
almost a watt from a 6.3V transformer.

-Chuck
---------
Chuck,
How do you connect your probe leads to the transformer output. Isn't the output side now independent of a ground reference? At my workbench, I use a 7A22 with two probes in differential setup. But my 465M is what I am using outside near the generator.
I found a 120 to 34V transformer I can use.
Bob
----------
The filament transformer complete isolates the primary from
the secondary electrically. So, I put a household plug on
the 120V side, and usually use a Pomona binding post to male
BNC adapter for the low voltage secondary.

Nothing to stop you from simply soldering a piece of RG58 that
is only terminated on one end, or soldering a BNC female to the
transformer, and using a BNC-BNC cable to connect that to the
scope.

-Chuck Harris

OK, I rigged up my 120 to 34V transformer through an on off switch. The output is connect to a terminal strip with a 100K ohm resistor across the output. I am getting a lot of distortion and wonder if I just have a cheap transformer.
Should the frame of the transformer be grounded?

Also, I am looking into buying a filament transformer and a I found some older filament transformers as as well as newer power transformers for sale. Is there a difference?
Bob


Re: Fw: You have been removed from TekScopes@groups.io

 

So did you click on the link to resume your subscription - if so all should be well. It was probably a transient problem with your or another ISP.

David

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Ken Wright via groups.io
Sent: 31 October 2020 17:39
To: TekScopes@groups.io
Subject: [TekScopes] Fw: You have been removed from TekScopes@groups.io

This is the message I receivedKen M0KHW ----- Forwarded message ----- From: TekScopes@groups.io <tekscopes+owner@groups.io>To: "kenwright309@yahoo.co.uk" <kenwright309@yahoo.co.uk>Sent: Friday, 30 October 2020, 10:09:01 GMTSubject: You have been removed from TekScopes@groups.io
Hello,
You have been automatically removed from TekScopes@groups.io because your Email Service Provider reported to us that message Re: source for blue filters for 2465 family scopes ??from TekScopes@groups.io has been marked as spam.


Fw: You have been removed from TekScopes@groups.io

Ken Wright
 

This is the message I receivedKen M0KHW ----- Forwarded message ----- From: TekScopes@groups.io <tekscopes+owner@groups.io>To: "kenwright309@yahoo.co.uk" <kenwright309@yahoo.co.uk>Sent: Friday, 30 October 2020, 10:09:01 GMTSubject: You have been removed from TekScopes@groups.io
Hello,
You have been automatically removed from TekScopes@groups.io because your Email Service Provider reported to us that message Re: source for blue filters for 2465 family scopes ??from TekScopes@groups.io has been marked as spam.

We suggest that you check your spam folder as soon as possible to see if your Email Service Provider has diverted other legitimate messages into it.

You will receive no more emails from that group. If this was a mistake, you can resume your subscription within the next 7 days by clicking the following link:

Resume Subscription

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If this happens repeatedly please check with your Email Service Provider to learn about how they decide to send feedback reports to list services (such as Groups.io groups).

The Groups.io Team


Re: Scope grounding and generators

Chuck Harris <cfharris@...>
 

The filament transformer complete isolates the primary from
the secondary electrically. So, I put a household plug on
the 120V side, and usually use a Pomona binding post to male
BNC adapter for the low voltage secondary.

Nothing to stop you from simply soldering a piece of RG58 that
is only terminated on one end, or soldering a BNC female to the
transformer, and using a BNC-BNC cable to connect that to the
scope.

-Chuck Harris

Robert Simpson via groups.io wrote:

Chuck,
How do you connect your probe leads to the transformer output. Isn't the output side now independent of a ground reference? At my workbench, I use a 7A22 with two probes in differential setup. But my 465M is what I am using outside near the generator.
I found a 120 to 34V transformer I can use.
Bob






Re: Scope grounding and generators

Robert Simpson
 

Chuck,
How do you connect your probe leads to the transformer output. Isn't the output side now independent of a ground reference? At my workbench, I use a 7A22 with two probes in differential setup. But my 465M is what I am using outside near the generator.
I found a 120 to 34V transformer I can use.
Bob


Re: refurbishing TM500 and TM5000 hardware

Kevin Oconnor
 

Most failures on these mainframes are blown pass transistors, rather than lytic caps.



I have 4 TM500 frames of various sizes. I can’t remember how many times I’ve replaced those pass transistors I’m some of them. Sometimes they seem to blow on their own and other times it was clearly a failed plugin.



I always felt it was a weak point in the overall system design of the modular interface approach.



Never have needed to replace caps in the frame.



Kevin


Removed from group

Ken Wright
 

To the moderator
I have been removed from this group due to a spurious posting in my name, I would like to re-join.
RegardsKen Wright M0KHW
kenwright309@yahoo.co.uk


Re: source for blue filters for 2465 family scopes ??

Chuck Harris <cfharris@...>
 

Bear in mind that the blue does nothing to improve the
contrast of the beam on P31 phosphors. It was chosen
entirely for esthetic reasons. It matched the tektronix
blue color used as a corporate color scheme.

-Chuck Harris

bob wrote:

EUREKA !!!

I found a source of film/plastic that almost completely imitates the original color film, and its CHEEEP !!

1 sheet thick seems to mimic the color of the factory quite closely, and if you like a darker blue color, put a second layer in.

https://www.amazon.com/gp/product/B008AXZ9M8/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

works GREAT !!!

-bob








Re: Modifying Type 109 for single-shot use?

Ed Breya
 

You should be able to make it into a DC-controlled, one-shot deal, but you may have to adjust the magnetic structure and coil bias such that it won't work in its normal resonant mode. Does it need to work normally too, or just one-shot? Without any magnetic mods, I think it should be able to do it if you can (over) drive the coil hard enough with the DC/step, but I don't know how much, or if the coil can take the extra power dissipation. I don't recall what form the Hg reed switch has - A, B, or C - but I think it's "A" so normally open with no field applied. If you make it so the desired fast edge happens when the reed is turned on, then the coil power needs only to be applied for a short time, I would think, and you can hit it pretty hard without much temperature rise. If the reed needs to stay closed for quite a while, then you may have coil dissipation issues.

I'd say give it a try and see how it works without magnetic mods, just with reasonable DC coil drive hooked in place of the normal signal. If you disable/disconnect the line charger supply, you can confirm switch operation with an ohmmeter, and not have to search for pulses on a scope. You may luck out and it will be fine with fairly low coil power. The reason I suspect that it may need quite a lot though, is that as I recall, the drive is supposed to be just enough to buzz the resonant armature to lightly jump the contacts into the Hg film, but not so much that the solid parts slam together. That would aggravate the wear, and slow things down. For DC drive, you won't have the benefit of resonance, and you will want to slam the contacts together enough to assure positive contact closure for the required time. On the plus side, the Hg reed should last virtually forever in this kind of application, assuming low duty factor.

Ed


Re: source for blue filters for 2465 family scopes ??

bob
 

EUREKA !!!

I found a source of film/plastic that almost completely imitates the original color film, and its CHEEEP !!

1 sheet thick seems to mimic the color of the factory quite closely, and if you like a darker blue color, put a second layer in.

https://www.amazon.com/gp/product/B008AXZ9M8/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

works GREAT !!!

-bob


Re: Scope grounding and generators

Chuck Harris <cfharris@...>
 

I usually just leave the 1M scope load to set the
output impedance.

But, since it is easy, try a few different values,
and see what looks the best.

50 ohms would not be a good idea, as it would draw
almost a watt from a 6.3V transformer.

-Chuck

Robert Simpson via groups.io wrote:

Some results:
1. My true RMS meter arrived, so I ran a few basic tests with the meter and the 465M.
After starting the generator and letting it warm up, I connected a 500W shop lamp for a resistivity load. TRMS meter showed about 130 V
Hooked the scope up one lead and took some pictures. Unfortunately although I was in tree shade, general glare resulted in marginal pictures. Using Photoshop I adjusted the brightness and color and got a just readable image
Looks like period is approximately 16ms or about 62.5 HZ.
Peaky barely sine wave

2. I think I have a 120 to 12V transformer. So I might try some tests with motor loads, such as my table saw and hand electric saw.
Question, should the output leads of the transformer be open or have a light load say 10K oms?
Bob






Re: Scope grounding and generators

Michael W. Lynch
 

If you are reading 62.5 Hz, then your engine is running slightly fast. Generators typically run at 3600 or 1800 (depends on whether they use a 2 pole or 4 pole rotor). Check your frequency at full rated load, I would guess that it will be closer to correct. Most mechanical governors have a speed adjustment that will allow slight changes to the full load RPMs to correct frequency at full load. Better generators, like HONDA and Yamaha have better governor calibration as well as better regulation.

--
Michael Lynch
Dardanelle, AR


Re: Scope grounding and generators

Robert Simpson
 

Some results:
1. My true RMS meter arrived, so I ran a few basic tests with the meter and the 465M.
After starting the generator and letting it warm up, I connected a 500W shop lamp for a resistivity load. TRMS meter showed about 130 V
Hooked the scope up one lead and took some pictures. Unfortunately although I was in tree shade, general glare resulted in marginal pictures. Using Photoshop I adjusted the brightness and color and got a just readable image
Looks like period is approximately 16ms or about 62.5 HZ.
Peaky barely sine wave

2. I think I have a 120 to 12V transformer. So I might try some tests with motor loads, such as my table saw and hand electric saw.
Question, should the output leads of the transformer be open or have a light load say 10K oms?
Bob


Re: source for blue filters for 2465 family scopes ??

Christian
 

I have a pile of misc scope filters - what's the exact PN you're looking for?


Modifying Type 109 for single-shot use?

Christian
 

I have one of these fascinating old beasts, and 'enjoyed' pulling it back into resonance and cleaning up the output step when it needed a new relay.

Pulses at a rep rate of a couple hundred hz are not always what I need of course (TLP work for ESD simulation, for example). I've been thinking of making up some sort of current-steering switch to give the electromagnet one hit - does anyone have experience with any mercury-wetted switch pulser like this in single-shot use?


Re: Scope grounding and generators

Roy Thistle
 

On Thu, Oct 29, 2020 at 07:18 PM, Greg Muir wrote:


So, I am now ending... with no further comments.[about the discussion so far.]
Here is a crude summary of the discussion so far:
OP (Robert) Is there a safe way to use my 465M to look at my generator output?
Chuck Use a filament transformer
Mike Check your grounds, and use the probe tip (only)
Stevenhorii Check the polarity of the outlets
Mac Check the grounding for stray voltage
Chuck Check the grounding
tenareze32 reports his generator damaged his coffee maker
Jean-Paul claims most generators have a distorted output/ use a Tek 212/ or float the 465
Glen: Check the grounding
Chuck: Don't float the 465
-: reports his generator damaged appliances/ use a constant voltage transformer
Tony: wonders if newer DSOs are isolated/thinks experienced people make grounding mistakes
@Oculus: recommends a Fluke Scopometer
Dave: thinks Tek 222, 222PS, and 224 are appropriate
OP (Robert) relates he has Briggs & Stratton Powermate 5000 (but didn't mention its used)
Carsten: use a differential probe
Greg: says be careful, experienced engineers have got it wrong/ put themselves in harms way/ he has a power analyzer
Roy: suggests a UPS can be used to do a crude check Robert's generator/mentions THD/potential backfeeds/questions the benefit of using a scope to measure THD/recommends an inverter generator
OP(Robert) generator is for temporary use/ wants to understand what the generator is outputing
Jean-Paul: recommends a SMPS (inverter) generator
Harrison: wants to know whether portable generators can damage modern electronics
Chuck:explains difference between contractor and standby generators
Greg:thinks a distortion analyzer is too complex a solution/ test under varying load/ UPS will trip on generators?bigger generator the better
Roy: Small portable Hot Dog stand owners use Honda inverter generators to power business and TV
Ed:cheap transformers saturate easily/ use a good step-down transformer
Roy: recommends a TRMS DMM
Greenboxmaven: get a used military generator
OP(Robert): reports he's army trained/following grounding suggestions/ and not familiar with generators.
Roy: RMS and TRMS meters/OP's generator won't be outputting a sine wave/Robert's old Fluke doesn't have MAX MIN or TRMS
OP(Robert): buys a cheap TRMS
Greg: Posts links about generators and power quality
Chuck: Claims UPS is insufficient
Stephen: Suggests problems could be improper generator field voltage
Paul:Suggests UPS has short run time/developing an electronic governor
Roy: Get a robust UPS
Chuck: scraps thousands of UPS/there are different grades of UPS, according to run-time limitations
Roy: explains what/why use a UPS
Greg: early UPS had square wave output/recommends taken measurements to avoid damage
Robers: Asks about Tek HV probes
Stevenhorii: Suggest optoisolators
Chuck: thinks Tek HV probes are appropriate/465 has sufficient isolation when using them/explains stiff power sources/only low BW needed for low band-limited signals
Roy: claims optoisolators are for isolation
Roy: wondering where there could be DC present on the AC output of a damaged generator/use a DMM first
Greg: relates engineers were mislead by making measurements with an un-shielded DMM in an RF near field/ recommend a low bandwidth analog meter for such cases.
Roy: recommends not using a Tek 465 to measure generator outputs/thinks the discussion so far is appropriate.
Greg: relates that, posts wander off topic/posters are competitive/has made power line measurements with Tek Scope, pigtail, and probes


Re: cap disch welding (was X10, X100 Readout Resistor)

SCMenasian
 

As I understand the OP's original problem, he had to join a very fine copper wire to a component or assembly. As a graduate student (50+ years ago), I used CD welders extensively. The best candidates for CD welding are low thermal and electrical conductivity materials. Thermal, so the hot zone remains at the point of contact for as long as possible and electrical, so the energy is deposited in the materials to be joined. Copper and silver are bad candidates in both respects. Also, there are problems joining very fine wires; determining the correct pulse energy is very tricky - too little and a weak or non-existent weld results- too much and the fine wire gets blasted away. In my work, I successfully welded 0.002" tungsten wires to support structures. In order to do this, an intermediate layer of platinum foil was necessary. Even though both tungsten and platinum have very high melting points, durable welds were possible. Much trial and error is necessary to get things right. Both mechanical pressure and pulse energy are critical parameters.

I'd suggest that, for the OP's application, a dab of silver-filled conductive epoxy might work. The circuit resistance is probably much higher than the joint; so, the electrical resistance of the epoxy joint might not affect electrical performance. For mechanical strength, the entire area could be potted in a high quality potting compound or epoxy.

scm


Tek 577 D1 Repair (B07xxxx)

Jack2015
 

1. 2020-Oct-24 :replaced a leaking electrolytic capacitor C124 on the A2 collector supply circuit board.
https://groups.io/g/TekScopes/photo/255563/6?p=Created,,,100,2,0,0

2. Oct-26 :The Collector supply disabled light turned on right at power on.
only one small spot could be seen on the screen.
https://groups.io/g/TekScopes/photo/255563/3?p=Created,,,100,2,0,0

Power consumption dropped from normal ~60W down to 51~52W.
Checked A3 power supply board:
+5V +5.12V
+12V +12.12V
-12V +0.72V<------NG!
+30V +29.83V
-30V -29.85V
+200V +191Vdc
+40V +40.07V
-40V -40.02V

U732 IC(7812,the -12V regulatpr IC on A3 board):
Input pin:+21.18Vdc ok! (should be +9.5V under normal conditions)
Common pin:+0.72 NG! (-12V)
Output pin:GND(0v) ok!

Replaced the U732(uA7812,1.5A) with a ST L7812CV(1.5A) on Oct-27 and fixed the issue.
I also replaced the U722 IC (+12V regulator IC,7812) and adjusted +30v/-30V to within +-0.2%(specs:+-0.5%).


3. Oct-29: A1 main board shorted

The traces disappeard suddenly after power on for about 30min,only an fine slant line about 2mm long could be seen.(it's a good news,much better than nothing on screen)
After inspections I found:
Power consumption jumped to ~90W(normal:~60W)
A3 power supply board:
+12V +0.6V<-------NG!
-12V -12.09V
+200V +191Vdc
-30V -29.98V
+30V +29.95V

Checked
U732 (7812,+12V regulator Ic) ok!
CR722 ok!
The resistance between +12v and GND: 0.5 ohm!
Some shorted part brought the +12V down to +0.6V and consumed about 30W!(it's about 2.5A if all come out of +12V rail)

After disconnecting P722 from A3 board the resistance between +12V and GND became about 2.3K ohm.this led me to A1 main board.
today I found the shorted part,it's C297 (15uf/20v,20% electrolytic capacitor).
https://groups.io/g/TekScopes/photo/255563/2?p=Created,,,100,2,0,0

I replaced the C297 with a panasonic 22uf 35V capacitor.
https://groups.io/g/TekScopes/photo/255563/1?p=Created,,,100,2,0,0

The Tek 577 D1 is in good working condition now except some noises(high frequency ripple) on the traces it comes and goes from time to time,
I will deal with it later.
https://groups.io/g/TekScopes/photo/255563/0?p=Created,,,100,2,0,0

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