Date   
Re: D10/5110 time base issue

Reginald Beardsley
 

The switches aren't opening and closing properly.

Does anyone know of a document describing how to adjust them? My naive attempts left much to be desired.

Thanks,
Reg

Re: 7633 is disassembled -- want any parts, CRT? not known to work at all

John Griessen
 

On 9/26/19 9:00 AM, EB4APL wrote:
while they are not equal some cards and semiconductors could be.
Yes, and I can give you photos that show the card part numbers and versions
and get ones that match. I would like $10 per card, and discount as the count goes up.
Shipping starts at about $15 and by the time you get to 3 cards $25 and so on.

Busy busy right now, but will get you photos in a few days.

--
John Griessen -- building lab gear for biologists
Ecosensory Austin TX blog.kitmatic.com

Re: 7633 is disassembled -- want any parts, CRT? not known to work at all

EB4APL
 

Hi John,

I understand that the scope was not working before disassembly so any part is suspicious. Anyway, which cards do you have and would you send some to Spain?

I would like to know how much do you want for them. I´m repairing a 7313 for my brother-in-law and while they are not equal some cards and semiconductors could be.

Best regards,

Ignacio EB4APL

El 26/09/2019 a las 1:34, John Griessen escribió:
7633 is disassembled -- want any parts, CRT?  not known to work at all.
---
El software de antivirus Avast ha analizado este correo electrónico en busca de virus.
https://www.avast.com/antivirus

Re: 1A5 differential comparator 'sponginess'

Albert Otten
 

Hi Chris,

This probably is thermal "DC shift due to overdrive". You might follow the checks in Section 6 Step 22. Unlike the 7A13 the 1A5 has no adjustments here. Note that is recovery is checked (also in the 7A13) at return to GND level, not at the switch to top level of the square wave (because there can be no long term drift in zero level of the Type 106, PG506 or the special overdrive test calibration fixture 067-0608-00).
The thermal drift could also be in the mainframe. What happens when you check recovery with an ordinary amplifier plugin in stead of the 1A5?
I don't own a 1A5 so I can't do a test myself.

Albert

On Wed, Sep 25, 2019 at 11:14 PM, cmjones01 wrote:


I've just become the proud owner of a 1A5 differential comparator
plugin for my 535A scope. It's a wonderful thing and its only real
fault was that the variable volts/cm pot was made of that awful
crumbly Tek plastic and had fallen apart. With that temporarily
shorted out while undergoing repair, the rest works really well after
a dose of DeoxIT D5.

However, it has one odd behaviour which I can't explain. The whole
point of the 1A5 is being able to work with signals much larger than
the scope's screen. However, if I feed this one a large positive
signal, the trace drifts upwards somewhat over a period several
seconds, then drifts back down slowly after that signal is removed.
The same happens the other way with a large negative signal. It
happens on both A and B inputs, and also when applying/removing a
large comparison voltage.

For example, I have it running right now set to 0.1V/cm. With a signal
of anything up to about 1V square wave from the calibrator, the
'ground' level of the trace stays constant, subject to the usual
long-term drift I'd expect. However, if I apply a 10V square wave,
still with the plugin set to 0.1V/cm, the 'ground' level wanders
slowly up about 0.8 of a division. It takes several seconds to do
this. If I turn the calibrator back down to 0.5V, the trace wanders
slowly back down. The signal is well within the plugin's rated
common-mode range.

Can anyone explain this? Are they all like that? My 7A13s, which
presumably have a similar architecture, don't suffer from it.

I'm wondering if there's some leakage somewhere which is charging
something up slowly, when given a large offset input signal.

Chris

Re: P6042 frequency response?

 

Hi Sean,
Not necessarily. Once again it is more likely that one of the five Hall Effect wires is open.

The Hall Effect circuit goes through a completely different path (DC to low frequency) in the P6042 from the AC path for the current transformer. You should check the differential outputs (+ and -) of M18, the differential amplifier used to amplify the Hall Effect Sensor signal. If you have a measurable signal there then check the collector of Q29 for a larger signal.

It will be easier to see the output of the Hall Effect Sensor while you are tracing it if you use a low frequency square wave (100Hz for example) where the current swings at least 50 mA above and below zero mA.

Dennis Tillman W7PF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of sdturne@q.com
Sent: Wednesday, September 25, 2019 9:26 PM
To: TekScopes@groups.io
Subject: Re: [TekScopes] P6042 frequency response?

If I clip it on a wire carrying pure dc, there is no trace deflection and there's a lot of spurious noise showing up. I assume this is a bad sign for the hall sensor. =[

Sean




--
Dennis Tillman W7PF
TekScopes Moderator

Re: P6042 frequency response?

@0culus
 

If I clip it on a wire carrying pure dc, there is no trace deflection and there's a lot of spurious noise showing up. I assume this is a bad sign for the hall sensor. =[

Sean

Re: P6042 frequency response?

@0culus
 

On Wed, Sep 25, 2019 at 05:30 PM, Dennis Tillman W7PF wrote:


Hi Sean,
I think that Chuck is correct about the Hall Effect Sensor. Those are
extremely simple devices and inherently reliable so I doubt it is bad. The
Hall Effect Sensor requires five of the wires in the cable so the odds are
very high that you have a broken wire. The good news is it sounds like the
split core AC transformer might be OK. The mating surface of the split core is
precisely lapped to close perfectly so they come in matching top / bottom
pairs. You might want to check to be sure they are lining up and mating
properly. These cores are also susceptible to cracking which could happen if
the probe was dropped or struck with a sharp blow.

In addition to making sure the core is completely closed (push the thumb
slider all the way forward over the detent until the Probe Unlocked" light
goes out) you should degauss the probe first every time you use it or switch
it to a different wire.

How do you know your function generator is able to put out a significant
current above 1MHz?

The HF roll off above 1MHz could be an indication there could be a problem
with the AC signal chain inside the P6042. One way to tell would be to check
the signal from the probe head where it comes out of the Attenuator Switch
inside the P6042. This would be at J80 which goes to the base of Q87.

Dennis Tillman W7PF

Hi Dennis,

I took the probe apart very carefully and examined all the wires and the cores. They all look to be intact. The faces of the split core have some light scratches but no apparent cracks.

Additionally, I don't know what I did, but now it has ac response all the way up to what my function generator can output (20 MHz, HP 3325B). So, maybe like the front panel of the amplifier box, it just needed exercise? I may still probe as you suggested just to be sure.

What's the best way to test the Hall sensor?

PS: it appears that the "probe unlock" light is out...is this one incandescent? And, how do you get into the little cylinder it lives in? The cap seems to be very tight.

Thanks!

Sean

Re: P6042 frequency response?

 

Hi Sean,
I think that Chuck is correct about the Hall Effect Sensor. Those are extremely simple devices and inherently reliable so I doubt it is bad. The Hall Effect Sensor requires five of the wires in the cable so the odds are very high that you have a broken wire. The good news is it sounds like the split core AC transformer might be OK. The mating surface of the split core is precisely lapped to close perfectly so they come in matching top / bottom pairs. You might want to check to be sure they are lining up and mating properly. These cores are also susceptible to cracking which could happen if the probe was dropped or struck with a sharp blow.

In addition to making sure the core is completely closed (push the thumb slider all the way forward over the detent until the Probe Unlocked" light goes out) you should degauss the probe first every time you use it or switch it to a different wire.

How do you know your function generator is able to put out a significant current above 1MHz?

The HF roll off above 1MHz could be an indication there could be a problem with the AC signal chain inside the P6042. One way to tell would be to check the signal from the probe head where it comes out of the Attenuator Switch inside the P6042. This would be at J80 which goes to the base of Q87.

Dennis Tillman W7PF

-----Original Message-----
From: Chuck Harris
Sent: Wednesday, September 25, 2019 7:53 AM

The P6042 is a fairly amazing example of making something work in spite of itself.

It is comprised of two current sensors, and a custom circuit that combines their output to give you your screen display.

The first sensor is simply a split core AC current transformer.
Because the core isn't infinite in size, it can only function at frequencies quite a lot higher than DC. Probably at its best 10KHz and above... all the way up to 50MHz.

The second sensor is a semiconductor hall effect magnetic field sensor, which is capable of detecting static magnetic fields...
perfect for measuring the magnetic fields that surround a piece of wire down to DC. It is however, only a low frequency device, capable of working from DC to about 10KHz.

To get the high performance DC to 50MHz that the 6042 is specified to have, it has to combine the low pass performance of the hall effect sensor, with the high pass performance of the split core AC current transformer. That is the function of the base unit.

The base unit contains a power supply, and a custom IC that interfaces to both of the current sensors in the probe, and combines their signals into a DC to 50MHz output. It is notoriously unreliable, and purely unavailable. You could replace it with a custom design using surface mount parts on a daughter board that plugged in its place... but it would require quite a bit of work.

It sounds like your unit has a non functioning DC hall effect sensor. It is often due to a broken wire in the probe's cable, but can be due to a broken hall effect sensor, or a bad custom
IC... It's diagnosis time.

-Chuck Harris


sdturne@q.com wrote:
Hi all,

Now that I've got power to the P6042, I was able to get it working pretty well after exercising the controls a lot. However, I am wondering something about how it operates. I understand that it's a combination current transformer and Hall effect sensor. I set up a simple resistive circuit fed that draws current from my function generator (set up to provide a sinusoid). However, there appears to be no AC response at all below a few tens of KHz, and the response varies wildly, peaking at a few hundred KHz and then rolling off significantly past 1 MHz. My gut feeling is that something is wrong with it, though this is my first current probe so I'm also willing to consider that it's faulty user.

Any tips on use and verification of performance are greatly appreciated. Thanks!

Sean



--
Dennis Tillman W7PF
TekScopes Moderator

Re: 7633 is disassembled -- want any parts, CRT? not known to work at all

Dave Daniel
 

Hi, John.

I can't think of anything else that I need at present. Once you dispose of the parts, though, I'm sure something will come up.

Thanks

Dave

On 9/25/2019 7:34 PM, John Griessen wrote:
7633 is disassembled -- want any parts, CRT?  not known to work at all.

7633 is disassembled -- want any parts, CRT? not known to work at all

John Griessen
 

7633 is disassembled -- want any parts, CRT? not known to work at all.

Re: P6042 frequency response?

@0culus
 

On Wed, Sep 25, 2019 at 07:53 AM, Chuck Harris wrote:


The P6042 is a fairly amazing example of making something
work in spite of itself.

It is comprised of two current sensors, and a custom circuit
that combines their output to give you your screen display.

The first sensor is simply a split core AC current transformer.
Because the core isn't infinite in size, it can only function
at frequencies quite a lot higher than DC. Probably at its
best 10KHz and above... all the way up to 50MHz.

The second sensor is a semiconductor hall effect magnetic field
sensor, which is capable of detecting static magnetic fields...
perfect for measuring the magnetic fields that surround a piece
of wire down to DC. It is however, only a low frequency device,
capable of working from DC to about 10KHz.

To get the high performance DC to 50MHz that the 6042 is
specified to have, it has to combine the low pass performance
of the hall effect sensor, with the high pass performance of
the split core AC current transformer. That is the function
of the base unit.

The base unit contains a power supply, and a custom IC that
interfaces to both of the current sensors in the probe, and
combines their signals into a DC to 50MHz output. It is notoriously
unreliable, and purely unavailable. You could replace it with
a custom design using surface mount parts on a daughter board
that plugged in its place... but it would require quite a bit
of work.

It sounds like your unit has a non functioning DC hall effect
sensor. It is often due to a broken wire in the probe's cable,
but can be due to a broken hall effect sensor, or a bad custom
IC... It's diagnosis time.

-Chuck Harris

Thanks, Chuck. Where would be the best place to continue diagnosis? If all else fails, I did not spend much on this (part of a larger package deal of things from hamfest), so if it ends up being purely educational and perhaps a parts mule for another one, so be it.

Sean

Re: P6042 frequency response?

@0culus
 

I have not disassembled the probe yet, but yes I was testing with it in the locked position.

Sean

On Wed, Sep 25, 2019 at 07:47 AM, David C. Partridge wrote:


Is the ball bearing present in the closing mechanism for the sensor? You were
testing with it fully closed I assume?

David
toggle quoted message Show qu ( #quoted-73529568 )

1A5 differential comparator 'sponginess'

cmjones01
 

I've just become the proud owner of a 1A5 differential comparator
plugin for my 535A scope. It's a wonderful thing and its only real
fault was that the variable volts/cm pot was made of that awful
crumbly Tek plastic and had fallen apart. With that temporarily
shorted out while undergoing repair, the rest works really well after
a dose of DeoxIT D5.

However, it has one odd behaviour which I can't explain. The whole
point of the 1A5 is being able to work with signals much larger than
the scope's screen. However, if I feed this one a large positive
signal, the trace drifts upwards somewhat over a period several
seconds, then drifts back down slowly after that signal is removed.
The same happens the other way with a large negative signal. It
happens on both A and B inputs, and also when applying/removing a
large comparison voltage.

For example, I have it running right now set to 0.1V/cm. With a signal
of anything up to about 1V square wave from the calibrator, the
'ground' level of the trace stays constant, subject to the usual
long-term drift I'd expect. However, if I apply a 10V square wave,
still with the plugin set to 0.1V/cm, the 'ground' level wanders
slowly up about 0.8 of a division. It takes several seconds to do
this. If I turn the calibrator back down to 0.5V, the trace wanders
slowly back down. The signal is well within the plugin's rated
common-mode range.

Can anyone explain this? Are they all like that? My 7A13s, which
presumably have a similar architecture, don't suffer from it.

I'm wondering if there's some leakage somewhere which is charging
something up slowly, when given a large offset input signal.

Chris

Re: D10/5110 time base issue

Harvey White
 

Uncalibrated?


Harvey

On 9/25/2019 8:16 AM, zenith5106 wrote:
On Wed, Sep 25, 2019 at 06:26 AM, Reginald Beardsley wrote:

However there is a significant (>10x) time base error.
Does anyone have any suggestions on likely suspects before I dig into it?
Are you sure the problem is in the T/B plug and not in the mainframe ?

/Håkan



Re: P6042 -- bad line cord

Roy Thistle
 

On Tue, Sep 24, 2019 at 04:18 AM, Chuck Harris wrote:


you could count on the students throwing
away enough to furnish an apartment every year
Yes! There are many international students here... and they discard the best stuff. Other students (foreign or not) never pick it up. Copper hounds (when they are not busy cutting the copper ground straps off or utility poles) cut the line cords off.

Re: D10/5110 time base issue

Jim Ford
 

Mine's a 5103N/D10 rather than a 5110N, so it must be an early one, FWIW.Jim Sent from my Verizon, Samsung Galaxy smartphone

-------- Original message --------From: Dave Seiter <d.seiter@...> Date: 9/25/19 10:19 AM (GMT-08:00) To: TekScopes@groups.io Subject: Re: [TekScopes] D10/5110 time base issue Not 100% sure, but the 1971 date is probably the intro of the series (D10, etc), while the 1976 date is when they changed the model numbers to the 5110 style.  As mentioned not too long ago, the model numbers of this series can be a little confusing.-Dave    On Wednesday, September 25, 2019, 09:17:11 AM PDT, Reginald Beardsley via Groups.Io <pulaskite=yahoo.com@groups.io> wrote: The sweep is too slow.  The factor varies depending upon  the timebase setting.  I was a bit surprised it works at all.  It took a bunch of knob twisting to get anything to appear and not every setting produces a display.  But it appears simply to be in need of cleaning and calibration.I'm going to take it apart and clean all the switch contacts and pots and do a calibration.  Then look for someone who wants a scope for audio work.  That 4" x 5" screen is really nice.The wiki gives a start date of 1976, but the manual is copyright 1971.  If the wiki end date of 1991 is correct, Tek sold these for 20 years which I find rather amazing.  The revision date on the manual I have is 1983.Have Fun!Reg

Re: P6042 -- bad line cord

Roy Thistle
 

On Tue, Sep 24, 2019 at 08:12 AM, greenboxmaven wrote:


ultimately decayed to green powder
Hi Bruce:
Yes, I've seen that. For those interested... one explanation is that the greenish powder (mostly basic copper carbonate) was the end process begun by the off gassing (or some other transfer mechanism) of chlorine from the PVC insulation.
Best regards and wishes.
Roy

Re: D10/5110 time base issue

Dave Seiter
 

Not 100% sure, but the 1971 date is probably the intro of the series (D10, etc), while the 1976 date is when they changed the model numbers to the 5110 style.  As mentioned not too long ago, the model numbers of this series can be a little confusing.
-Dave

On Wednesday, September 25, 2019, 09:17:11 AM PDT, Reginald Beardsley via Groups.Io <pulaskite=yahoo.com@groups.io> wrote:

The sweep is too slow.  The factor varies depending upon  the timebase setting.  I was a bit surprised it works at all.  It took a bunch of knob twisting to get anything to appear and not every setting produces a display.  But it appears simply to be in need of cleaning and calibration.

I'm going to take it apart and clean all the switch contacts and pots and do a calibration.  Then look for someone who wants a scope for audio work.  That 4" x 5" screen is really nice.

The wiki gives a start date of 1976, but the manual is copyright 1971.  If the wiki end date of 1991 is correct, Tek sold these for 20 years which I find rather amazing.  The revision date on the manual I have is 1983.

Have Fun!
Reg

Re: P6042 -- bad line cord

Roy Thistle
 

On Tue, Sep 24, 2019 at 08:19 PM, @0culus wrote:


grafting on a cheap harbor freight plug
Hi Sean:
Good to hear you got it going!
There are dozens of videos on YouTube, discussing/showing replacing A.C. line cords. (They cover things like "why", "safety grounding", "how to identify the neutral, hot, and ground wires", "conductor size', "strain relief", "two conductor versus three conductor", "cable quality",... etc.).
Mr. Carlson of Mr. Carlson's Lab, Dave Jones of EEVblog, Big Clive, and many others.
If there is something essentially unique about the A.C. line cord, or strain relief, or type of cable, or quality of cable, on a P6042, I'd really like to know. (Maybe someone reading knows?)
Best regards. Best wishes.
Roy

Re: D10/5110 time base issue

Jim Ford
 

Yep, I love the large screen and brought, sharp trace on mine with the same plug-ins exactly.  Got it on Craigslist for audio work.   Now if I can just find the time to do some!It is my go-to scope for the Basic Electronics class I'm teaching in my garage lab.  Only one student so far but that's just a matter of logistics.I don't have your issue with the timebase (thank God).Jim Ford Sent from my Verizon, Samsung Galaxy smartphone

-------- Original message --------From: "Reginald Beardsley via Groups.Io" <pulaskite=yahoo.com@groups.io> Date: 9/25/19 9:17 AM (GMT-08:00) To: TekScopes@groups.io Subject: Re: [TekScopes] D10/5110 time base issue The sweep is too slow.  The factor varies depending upon  the timebase setting.  I was a bit surprised it works at all.  It took a bunch of knob twisting to get anything to appear and not every setting produces a display.  But it appears simply to be in need of cleaning and calibration.I'm going to take it apart and clean all the switch contacts and pots and do a calibration.   Then look for someone who wants a scope for audio work.  That 4" x 5" screen is really nice.The wiki gives a start date of 1976, but the manual is copyright 1971.  If the wiki end date of 1991 is correct, Tek sold these for 20 years which I find rather amazing.  The revision date on the manual I have is 1983.Have Fun!Reg