Date   

P6042 Repairing the Probe Cable (WAS: P6042 -- bad line cord)

 

Hi Dwayne,

Your solution to use an HDMI cable as a substitute for the P6042 cable
sounds like a great idea. Before I do any more damage to my P6042s
(explanation follows) I would like to hear from anyone else that
successfully fixed the cable from the head first.

A year ago I mentioned to a friend, who has P6042s, that my P6042s were
becoming intermittent where the cable from the probe entered the P6042. He
said it was very easy to fix this by cutting off the cable at the chassis,
removing the piece inside the chassis, and soldering the remaining cable in
its place. That sounded really simple. What could possibly go wrong?

After trying this myself on the two P6042s I am absolutely certain he never
tried this himself. From personal experience I would advise anyone to avoid
doing this until you have no choice because your cable is so broken that the
P6042 will not work no matter how much you wiggle or push on the cable.

The cable has many conductors in it. To be flexible Tek chose to make six of
the conductors extremely fine. They are the critical AC and DC signal
carrying wires from the head. These wires are by far the finest wire I have
ever seen. Until now I have never found a wire that is impossible to work
on. I have many insulation stripping tools including wire wrap wire
strippers for #28 and #30 gauge wire, Thermal Strippers (required by manned
space missions I once worked on), Telephone linesman strippers, etc. The
insulation on these wires was so delicate that any heat from a thermal wire
stripper or tugging on the insulation with a mechanical wire stripper broke
the entire wire right off.

After a few hours of experimenting I discovered that the heat from a
soldering iron a few inches away from the wires would soften the insulation.
At last I thought I could proceed to tin these wires. The lowest heat that
melted the solder (eutectic 63/37) I use DISSOLVED the copper wire because
it was so thin. Another hour of failed experiments passed before I gave up
trying to tin the wires.

The last thing I could think of that might work was to apply a little solder
in the hole the old wire was soldered to. To do this I used the absolute
minimum temperature necessary to melt the eutectic solder I use. Once the
solder in the hole was melted I pushed an unstripped wire into it. The
insulation puddled on top of the solder so that automatically stripped the
insulation from the wire. After a few attempts I managed to get the copper
wire imbedded in the molten solder. Whether it was in good electrical
contact or just trapped in a blob of cold solder was unknown. This is not my
idea of how to connect a wire to a PC board but it was the best I could do.

After I finished replacing all of the cable wires I confirmed there was
continuity on each wire from inside the chassis to the probe head. My two
P6042s are now sitting under my desk. They never worked after I replaced the
cable. I despair every time I look at them that I ruined an incredibly
valuable instrument.

Dennis Tillman W7PF

-----Original Message-----
From: Dwayne Reid
Sent: Sunday, September 22, 2019 12:39 PM
Subject: Re: [TekScopes] P6042 -- bad line cord

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




--
Dennis Tillman W7PF
TekScopes Moderator


Re: P6042 -- bad line cord

 

This is another reminder that you can't include HTML or photos in your posts.

It appears Bob sent part of the HTML that contained the article and photos. TekScopes is text only. I think all the vertical symbols were TekScopes attempt to represent the borders around the HTML and/or photo.

Dennis Tillman W7PF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Dennis Tillman W7PF
Sent: Sunday, September 22, 2019 3:43 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] P6042 -- bad line cord

Hi Bob,
Something strange happened when I received a copy of your post to TekScopes.
What I received was the sentence "Teardown: The Tektronix P6042 current probe is a classic" followed by a seemingly random series of vertical separator symbols. Did anyone else get the same thing?
That's why I asked for a link to the article (which I have since received).
The exact same thing appears if you go to TekScopes and look at the message there.

Could you send me OFF LIST (dennis at ridesoft dot com) the original email you posted so maybe I can figure out if there is a problem with how Groups.io handled it. Also, what email app do you use.

Thanks, Dennis

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Bob Albert via Groups.Io
Sent: Saturday, September 21, 2019 8:53 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] P6042 -- bad line cord

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 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








--
Dennis Tillman W7PF
TekScopes Moderator





--
Dennis Tillman W7PF
TekScopes Moderator


Re: P6042 -- bad line cord

Bob Albert
 

I mean across any conductors you suspect are open.  It's unlikely that two are open; probably all open or just one.  But strange things can happen.  Try every combination until you find a reading that shouldn't be.

On Sunday, September 22, 2019, 04:52:31 PM PDT, <sdturne@q.com> wrote:

On Sun, Sep 22, 2019 at 04:47 PM, Bob Albert wrote:


You can measure small capacitance.  Whatever your means of measuring
capacitance, put the smallest value you can measure on it and take a
reading.  Then connect the power cord across that and measure again.  You
may be able to see enough difference to determine whether you are adding 2 pF
or 100 pF.
Bob
OK. You mean across the neutral and hot conductors?

Sean


Re: P6042 -- bad line cord

Sean Turner
 

On Sun, Sep 22, 2019 at 04:47 PM, Bob Albert wrote:


You can measure small capacitance.  Whatever your means of measuring
capacitance, put the smallest value you can measure on it and take a
reading.  Then connect the power cord across that and measure again.  You
may be able to see enough difference to determine whether you are adding 2 pF
or 100 pF.
Bob
OK. You mean across the neutral and hot conductors?

Sean


Re: P6042 -- bad line cord

Bob Albert
 

You can measure small capacitance.  Whatever your means of measuring capacitance, put the smallest value you can measure on it and take a reading.  Then connect the power cord across that and measure again.  You may be able to see enough difference to determine whether you are adding 2 pF or 100 pF.
Bob

On Sunday, September 22, 2019, 04:37:36 PM PDT, <sdturne@q.com> wrote:

On Sun, Sep 22, 2019 at 02:40 PM, Bob Albert wrote:


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
Hi Bob,

I unfortunately don't have any way to measure pF, only down to nF. I'll try TDR.

Sean


Re: P6042 -- bad line cord

Glenn Little
 

He appears to have quoted a typical google books scan.


Glenn

On 9/22/2019 6:42 PM, Dennis Tillman W7PF wrote:
Hi Bob,
Something strange happened when I received a copy of your post to TekScopes.
What I received was the sentence "Teardown: The Tektronix P6042 current probe is a classic" followed by a seemingly random series of vertical separator symbols. Did anyone else get the same thing?
That's why I asked for a link to the article (which I have since received).
The exact same thing appears if you go to TekScopes and look at the message there.

Could you send me OFF LIST (dennis at ridesoft dot com) the original email you posted so maybe I can figure out if there is a problem with how Groups.io handled it. Also, what email app do you use.

Thanks, Dennis

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Bob Albert via Groups.Io
Sent: Saturday, September 21, 2019 8:53 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] P6042 -- bad line cord

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 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







--
-----------------------------------------------------------------------
Glenn Little ARRL Technical Specialist QCWA LM 28417
Amateur Callsign: WB4UIV wb4uiv@arrl.net AMSAT LM 2178
QTH: Goose Creek, SC USA (EM92xx) USSVI LM NRA LM SBE ARRL TAPR
"It is not the class of license that the Amateur holds but the class
of the Amateur that holds the license"


Re: P6042 -- bad line cord

Sean Turner
 

On Sun, Sep 22, 2019 at 02:40 PM, Bob Albert wrote:


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
Hi Bob,

I unfortunately don't have any way to measure pF, only down to nF. I'll try TDR.

Sean


Did I discover a bug?

DW
 

When I am composing a message on a mobile device (android smart phone) there have been occasions which I did not decide to submit but the message is submitted without pushing the submit button has anyone encountered this?


Re: P6042 -- bad line cord

Jim Ford
 

Me, too.Jim Ford Sent from my Verizon, Samsung Galaxy smartphone

-------- Original message --------From: Dennis Tillman W7PF <dennis@ridesoft.com> Date: 9/22/19 3:42 PM (GMT-08:00) To: TekScopes@groups.io Subject: Re: [TekScopes] P6042 -- bad line cord Hi Bob,Something strange happened when I received a copy of your post to TekScopes.What I received was the sentence "Teardown: The Tektronix P6042 current probe is a classic" followed by a seemingly random series of vertical separator symbols. Did anyone else get the same thing?That's why I asked for a link to the article (which I have since received).The exact same thing appears if you go to TekScopes and look at the message there.Could you send me OFF LIST (dennis at ridesoft dot com) the original email you posted so maybe I can figure out if there is a problem with how Groups.io handled it. Also, what email app do you use.Thanks, Dennis -----Original Message-----From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Bob Albert via Groups.IoSent: Saturday, September 21, 2019 8:53 PMTo: TekScopes@groups.ioSubject: Re: [TekScopes] P6042 -- bad line cord Teardown: The Tektronix P6042 current probe is a classic| | | |  |  | | || |  | Teardown: The Tektronix P6042 current probe is a classicPaul RakoThe 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-- Dennis Tillman W7PFTekScopes Moderator


Re: P6042 -- bad line cord

TomC
 

Dennis,

I got the same garbled email as you got.

A search for "Tektronix P6042 current probe is a classic" got the EDN article as the first hit.

Tom

On 9/22/2019 3:42 PM, Dennis Tillman W7PF wrote:
Hi Bob,
Something strange happened when I received a copy of your post to TekScopes.
What I received was the sentence "Teardown: The Tektronix P6042 current probe is a classic" followed by a seemingly random series of vertical separator symbols. Did anyone else get the same thing?
That's why I asked for a link to the article (which I have since received).
The exact same thing appears if you go to TekScopes and look at the message there.
Could you send me OFF LIST (dennis at ridesoft dot com) the original email you posted so maybe I can figure out if there is a problem with how Groups.io handled it. Also, what email app do you use.
Thanks, Dennis

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Bob Albert via Groups.Io
Sent: Saturday, September 21, 2019 8:53 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] P6042 -- bad line cord
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 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


Re: P6042 -- bad line cord

 

Hi Bob,
Something strange happened when I received a copy of your post to TekScopes.
What I received was the sentence "Teardown: The Tektronix P6042 current probe is a classic" followed by a seemingly random series of vertical separator symbols. Did anyone else get the same thing?
That's why I asked for a link to the article (which I have since received).
The exact same thing appears if you go to TekScopes and look at the message there.

Could you send me OFF LIST (dennis at ridesoft dot com) the original email you posted so maybe I can figure out if there is a problem with how Groups.io handled it. Also, what email app do you use.

Thanks, Dennis

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Bob Albert via Groups.Io
Sent: Saturday, September 21, 2019 8:53 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] P6042 -- bad line cord

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








--
Dennis Tillman W7PF
TekScopes Moderator


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@planet.eon.net>
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

Sean Turner
 

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@planet.eon.net>
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

Sean Turner
 

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@ridesoft.com>
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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| | |

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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...
|

|

|

On Sunday, September 22, 2019, 09:40:09 AM PDT, Dennis Tillman W7PF <dennis@ridesoft.com> 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.

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