Date   
Re: P6042 -- bad line cord

Dwayne Reid
 

Hi there, Sean.

I'm not near my unit right now, but isn't it just a Heyco strain relief? There is a special pliers that squeezes the movable portion into the other half if so. I often fake it using small vise grips on the outside portion and needle-nose pliers on the inside portion.

But I could be mistaken. I'll have a look later (today, I hope).

dwayne

At 03:31 PM 9/22/2019, sdturne@q.com wrote:

The probe cord might be problematic, but the problem at hand here is indeed the AC line cord. Today I desoldered it and there is definitely no continuity on either hot, neutral, or ground. I cannot, however, seem to figure out how to actually get the cord out of the chassis. The little strain relief thing that attaches it to the chassis has resisted all my efforts so far.

Sean
--
Dwayne Reid <dwayner@...>
Trinity Electronics Systems Ltd Edmonton, AB, CANADA
780-489-3199 voice 780-487-6397 fax 888-489-3199 Toll Free
www.trinity-electronics.com
Custom Electronics Design and Manufacturing

Re: P6042 -- bad line cord

Bob Albert
 

Before you work on the strain relief any more, put your capacitance bridge on the power cord to see which end is open.  Once you determine that, you can replace the connector or shorten the cable, etc.
You will measure around 2 pF across the end with the fault, and quite a bit more at the good end.
Your TDR pulser will do it too.
Bob

On Sunday, September 22, 2019, 02:31:49 PM PDT, <sdturne@q.com> wrote:

On Sun, Sep 22, 2019 at 12:38 PM, Dwayne Reid wrote:


Hi there, Sean.

When you said "bad line cord", I assumed that you meant the AC power cord.
However, upon reading subsequent messages, I'm now guessing that you are
talking about the cord between the current probe and the chassis.

I have a P6042 where the probe cable has died many times. I just kept cutting
it shorter and shorter. However, it finally got to the point where I had to
replace the cable.

I used a HDMI cable and cut the HDMI plugs off. Lots of individually-shielded
pairs.

Working fine so far but I suspect that the particular HDMI cable that I chose
is also not suited for continuous flexing.

Just a suggestion.

dwayne
The probe cord might be problematic, but the problem at hand here is indeed the AC line cord. Today I desoldered it and there is definitely no continuity on either hot, neutral, or ground. I cannot, however, seem to figure out how to actually get the cord out of the chassis. The little strain relief thing that attaches it to the chassis has resisted all my efforts so far.

Sean

Re: P6042 -- bad line cord

@0culus
 

On Sun, Sep 22, 2019 at 12:38 PM, Dwayne Reid wrote:


Hi there, Sean.

When you said "bad line cord", I assumed that you meant the AC power cord.
However, upon reading subsequent messages, I'm now guessing that you are
talking about the cord between the current probe and the chassis.

I have a P6042 where the probe cable has died many times. I just kept cutting
it shorter and shorter. However, it finally got to the point where I had to
replace the cable.

I used a HDMI cable and cut the HDMI plugs off. Lots of individually-shielded
pairs.

Working fine so far but I suspect that the particular HDMI cable that I chose
is also not suited for continuous flexing.

Just a suggestion.

dwayne
The probe cord might be problematic, but the problem at hand here is indeed the AC line cord. Today I desoldered it and there is definitely no continuity on either hot, neutral, or ground. I cannot, however, seem to figure out how to actually get the cord out of the chassis. The little strain relief thing that attaches it to the chassis has resisted all my efforts so far.

Sean

Re: P6042 -- bad line cord

Dwayne Reid
 

Hi there, Sean.

When you said "bad line cord", I assumed that you meant the AC power cord. However, upon reading subsequent messages, I'm now guessing that you are talking about the cord between the current probe and the chassis.

I have a P6042 where the probe cable has died many times. I just kept cutting it shorter and shorter. However, it finally got to the point where I had to replace the cable.

I used a HDMI cable and cut the HDMI plugs off. Lots of individually-shielded pairs.

Working fine so far but I suspect that the particular HDMI cable that I chose is also not suited for continuous flexing.

Just a suggestion.

dwayne

At 09:49 PM 9/21/2019, sdturne@q.com wrote:

Hi all,

Among other things I bought at hamfest, I got a P6042 current probe that won't power on. I believe all that may be wrong with it is a bad line cord, as there's no continuity between chassis and earth. Also, the hot conductor is only putting out about 30Vrms.

Is there a recommended way to replace it with a better cord? It seems super tiny gauge anyway.

Thanks,

Sean
--
Dwayne Reid <dwayner@...>
Trinity Electronics Systems Ltd Edmonton, AB, CANADA
780-489-3199 voice 780-487-6397 fax 888-489-3199 Toll Free
www.trinity-electronics.com
Custom Electronics Design and Manufacturing

Re: P6042 -- bad line cord

@0culus
 

Yes, that is the article.

Sean

Re: P6042 -- bad line cord

Siggi
 

Probably this is the article <
https://www.edn.com/design/test-and-measurement/4442795/Teardown--The-Tektronix-P6042-current-probe-is-a-classic
?

On Sun, Sep 22, 2019 at 12:40 PM Dennis Tillman W7PF <@Dennis_Tillman_W7pF>
wrote:

Hi Sean,
What article are you referring to?
A link to it would be appreciated.
Dennis Tillman W7PF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of
sdturne@q.com
Sent: Saturday, September 21, 2019 9:09 PM

Interesting article, but I guess I should rephrase this...anyone got a
DEAD P6042 that I could get the line cord out of?

Sean




--
Dennis Tillman W7PF
TekScopes Moderator



Re: P6042 -- bad line cord

Bob Albert
 

Teardown: The Tektronix P6042 current probe is a classic

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Teardown: The Tektronix P6042 current probe is a classic

Paul Rako

The Tektronix P6042 current probe, introduced in 1969, allows you to understand and troubleshoot reactive circui...
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On Sunday, September 22, 2019, 09:40:09 AM PDT, Dennis Tillman W7PF <@Dennis_Tillman_W7pF> wrote:

Hi Sean,
What article are you referring to?
A link to it would be appreciated.
Dennis Tillman W7PF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of sdturne@q.com
Sent: Saturday, September 21, 2019 9:09 PM

Interesting article, but I guess I should rephrase this...anyone got a DEAD P6042 that I could get the line cord out of?

Sean




--
Dennis Tillman W7PF
TekScopes Moderator

Re: P6042 -- bad line cord

 

Hi Sean,
What article are you referring to?
A link to it would be appreciated.
Dennis Tillman W7PF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of sdturne@q.com
Sent: Saturday, September 21, 2019 9:09 PM

Interesting article, but I guess I should rephrase this...anyone got a DEAD P6042 that I could get the line cord out of?

Sean




--
Dennis Tillman W7PF
TekScopes Moderator

Re: 577 U722 thermal insulator?

DW
 

It's possible that a IC died on me. I might also try to work backwards from the base of the test fixture and see where the broken link is. At the test fixture using an oscilloscope the probe will be on base and the other on ground, correct? I have a differential probe so not as much worries shorting out components with the ground lead.

Re: 577 U722 thermal insulator?

DW
 

Thanks, I am trying to find any possible situation which would explain the no functioning step generator, something obvious that might be overlooked such as a missing thermal pad or a wire not making connection. When I recapped the power supply board electrolytic and all tantalum it worked perfectly fine. Some how somewhere something went wrong when I was working on recapping the main board excluding ceramic disk. I didn't throw away any of the components I removed, maybe I should start putting them back in? Maybe start with the smallest capacitance tantrums first then possibly a few of those electrolytic capacitors and see if it works while leaving the larger value tantalum capacitors for later.

Re: P6042 -- bad line cord

@0culus
 

On Sat, Sep 21, 2019 at 09:15 PM, Bob Albert wrote:


I used to have one but the jaws got messed up and I sold it to some guy who
wanted a shot at repairing it.  I have no idea what he did with it.
I had built a power supply that was entirely adequate.  But I don't remember
anything about it.
Bob
Ahh, it's all good. The article you mentioned is a rather good read. Interesting that it manages to outperform the newer ones.

BTW, anyone can feel free to contact me off list if you happen to have anything available. Thanks!!

Sean

Re: 577 U722 thermal insulator?

Mlynch001
 

DW,

As I read the manual U722 does not require an insulator. Mine had thermal conductive grease on it.

Reference: 577-D1/D2 Service Manual 070-1414-00 - Sec. 8 Pg.12a for Unit Illustration, showing assembly details and Sec. 8 Pg.11 Item # 78 (U722) showing required mounting parts.

--
Michael Lynch
Dardanelle, AR

577 U722 thermal insulator?

DW
 

This is on the power supply board, does this transistor require a thermal pad? Thanks

Re: P6042 -- bad line cord

Bob Albert
 

I used to have one but the jaws got messed up and I sold it to some guy who wanted a shot at repairing it.  I have no idea what he did with it.
I had built a power supply that was entirely adequate.  But I don't remember anything about it.
Bob

On Saturday, September 21, 2019, 09:09:41 PM PDT, <sdturne@q.com> wrote:

Interesting article, but I guess I should rephrase this...anyone got a DEAD P6042 that I could get the line cord out of?

Sean

Re: P6042 -- bad line cord

@0culus
 

Interesting article, but I guess I should rephrase this...anyone got a DEAD P6042 that I could get the line cord out of?

Sean

Re: P6042 -- bad line cord

Bob Albert
 

Teardown: The Tektronix P6042 current probe is a classic

|
|
|
| | |

|

|
|
| |
Teardown: The Tektronix P6042 current probe is a classic

Paul Rako

The Tektronix P6042 current probe, introduced in 1969, allows you to understand and troubleshoot reactive circui...
|

|

|

On Saturday, September 21, 2019, 08:49:45 PM PDT, sdturne@q.com <sdturne@q.com> wrote:

Hi all,

Among other things I bought at hamfest, I got a P6042 current probe that won't power on. I believe all that may be wrong with it is a bad line cord, as there's no continuity between chassis and earth. Also, the hot conductor is only putting out about 30Vrms.

Is there a recommended way to replace it with a better cord? It seems super tiny gauge anyway.

Thanks,

Sean

P6042 -- bad line cord

@0culus
 

Hi all,

Among other things I bought at hamfest, I got a P6042 current probe that won't power on. I believe all that may be wrong with it is a bad line cord, as there's no continuity between chassis and earth. Also, the hot conductor is only putting out about 30Vrms.

Is there a recommended way to replace it with a better cord? It seems super tiny gauge anyway.

Thanks,

Sean

Re: Morning fun - working scope with no tubes?

 

Hi Robin,
You are referring to the Long Tail Pair which is an incredibly versatile circuit that has been used for over 80 years n tube circuits, transistor circuits, and integrated circuits.

Wikipedia includes the historical background of this circuit in their article on Differential Amplifiers (the Long tail Pair is a simple differential amplifier):
https://en.wikipedia.org/wiki/Differential_amplifier

An explanation of how the vacuum tube Long Tail Pair works is given at
http://www.valvewizard.co.uk/dcltp.html

Fender (and many others) used the Long Tail Pair as a phase inverter in their guitar amplifiers:
https://www.tdpri.com/threads/how-the-long-tail-pair-phase-inverter-works.519077/

Although the Long Tail Pair circuit was originally developed for vacuum tube amplifiers it is so general it works as well for transistors. This article describes how the transistor version works and how it is used extensively in IC OpAmps and Differential Comparators:
https://www.electronics-notes.com/articles/analogue_circuits/transistor/long-tailed-pair-circuit.php

Dennis Tillman W7PF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Robin_Birch
Sent: Friday, September 20, 2019 3:44 PM

Yes,
Designing stuff so that it was, as much as possible, independent of the particular characteristics of a given device as it aged or cane from various suppliers, was one of the great skills of tube design,.



--
Dennis Tillman W7PF
TekScopes Moderator

Re: Morning fun - working scope with no tubes?

 

Hi Tom,
I just checked on-line dictionaries from Merriam-Webster, Webster's Online Dictionary, Cambridge English Dictionary, Collins English Dictionary, and on and on. They all provide definitions for it.

Uh Oh! Did I fall for your trick and prove your point because I was gullible enough to challenge your claim? :)

Dennis Tillman W7PF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Tom Miller
Sent: Friday, September 20, 2019 5:40 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Morning fun - working scope with no tubes?

An old saw comes to mind here. Did you know the word gullible is not in the dictionary?

Regards




--
Dennis Tillman W7PF
TekScopes Moderator

Re: Circuit boards used to demo scopes\ c]

Richard Tyner <shawneesdad@...>
 

Thank you Siggi and Dave

I appreciate the information

73 Richard W4MCD