Date   

Re: Tek 2467B Erratic Intensity controls

peter bunge
 

Thanks Siggi and Chuck, I have been printing the 2467B manual I bought from
Artekmedia. I hate working from a computer screen and like to have paper to
highlight or write notes on. I will check the A5 capacitors and am reading
the manual.
I bought a spare horizontal chip and sequencer chip on Ebay and, because
the guy seemed to know about these problems asked about my issues. Here,
with his permission, are his replies through Ebay's limited messages. I
have not edited his English which I'm sure is much better than my rendition
of his language. I am very fortunate to have stumbled on this source of
knowledge. (I bought the chips for a dead 2465, not my 2467B)

Hi Peter!

Many thanks for your purchases and for repeated customer.

To answer on your questions, I might not have more knowledge than yours, I
developed some experience about these magnificent scopes when I did some
work on them long time time ago, I learned some but I don’t know the most
of it, I sold all of them and kept one 2465B and some spare parts that I
put them for sale here, any regarding the problem you have I don’t think
the U650 is the one because I had the same problem before...

...and I found the problem coming from some leaking SMD electrolytic caps
on the controller board, they are 4 of them there need to be replaced, I
did it then the screen came back to work correctly, other thing, they are
more of electrolytic caps on the main board need to be checked, they are
all aged more 20 years, but the one in the mentioned they go bad often,
other thing make sure if any cold solder somewhere in any part by using a
pencil and touch parts feet here and there........

You never know you can find one cold solder somewhere, other important
thing, you need to check all electrolytic caps in the main power supply,
some go bad often too, check if any acid leaks or swollen cap, these are
the first thing you need to do, other easy way I use to do, I use to have
multiple scopes 2465s so I keep swap the hybrid ICs until I find one is
bad, especially the vertical IC and Zaxis go bad faster than others the
2465 and 2467 have the same hybrid modules, you can do it....

As you mentioned the memory battery 🔋, it doesn’t have anything to do with
your problem because when the battery goes bad or low in power the stored
calibration data will vanished then you will have a serious problem, you
will start to see on the screen in the place of readout lines like this
???????????????, so you need to replace the battery by new one and you need
to recalibrate your scope again, these scopes have more than 20 years in
their lives........

So it is time to replace the battery before you loose the stored
calibration data, if you know how to do it then do now to avoid any future
calibration problem.

Regarding the question about 0244-00 or 0244-01 if any difference, I think
they are the same with a little bit of changes from the manufacturer, 00 is
the earlier 01 is the later but they have the same pin out and work the
same too.

Once I had a talk with the engineer who developed the 2465, it was a quiet
honor to talk to him.....

I did ask him about about a problem o had, the screen was acting
erratically and sometimes go away, I swapped all the modules, checked every
part, but I couldn’t find it, he right a way told me check a coil with 4
feet near by the Zaxis vertical maybe, he said one of the foot has cold
solder, I was shocked he was right !! I resolder it and worked fine, and I
did ask hi about the U800 problems too, it is a customs complex IC they go
bad over time because of excessive heat, he said when......

He said when we created this IC they didn’t know it will get hot 🥵 and
they didn’t design it with a socket to be easy to replace it without
damaging the PCB, he said by the time the IC started to fail over time it
was to late to redesign it with socket because the production line of this
scope cane to end, he advices me to add a socket to it if I want to and to
add a heat sink on top to reduce the heat and the IC will last longer, but
make sure the heat sink don’t connect the 2 screws together…

Because the 2 screws that hold the U800 one of them has positive voltage,
so avoid to screw a heat sink on both screws, just one side and other screw
left alone to avoid to short it, there is an article online showing how to
add a heat sink to U800 safely.

I hope I gave you some hints that can help you, if you have more questions
just ask and thanks for your purchases….

Oh I forgot to answer your question regarding how to remove the U800, well,
back then I used a pump with heated tip in one piece, i desoldered one foot
after another and make sure the foot is clear, and then after I finish all
I put a flat screw driver underneath of the IC and try to push up slowly, I
don’t force it, if it doesn’t move up I will go back and see if any foot
still not cleared, it is a difficult task and slow but it is better to be
in safe mode than damage the IC or PCB….

Now I have a much better electric pump desolder gun with controlled
temperature, it does a very good job and faster with safe temperature.

Good luck

On Sat, Nov 30, 2019 at 4:20 AM Siggi <siggi@...> wrote:

The comparator U2510, an LM311, is used to compare the DAC output to pot
readings, and the MPU uses this with successive approximation to make a
software ADC. This is described in the “Theory of Operation” section.

The trigger hybrid is not involved in pot scanning, though otherwise it
works the way Chuck describes it.

On Sat, Nov 30, 2019 at 04:49 Chuck Harris <cfharris@...> wrote:

There is no ADC part in the 2465 family scopes.

There is a DAC that is used as a part of an ADC
that is made from the DAC, CPU, MUX's, Sample and
Hold cells, and the trigger hybrid. The trigger
hybrid is used as the comparator that compares the
DAC output to the pot's wiper voltage.

The voltages get to the trigger hybrid by way of
a pair of muxes.

The capacitors referred to in the post are on the
A5 controller card on scopes with serial numbers
greater than B049999.

They are ordinary power supply bypass capacitors,
that because of the abuse of their being soldered
to the board by an oven, leak electrolyte all over
themselves, and the circuit board. The electrolyte
is highly corrosive to copper, and highly conductive
to electricity. It eats the copper traces, and
shorts out other components and traces.

They are the only surface mount electrolytic capacitors
on the board. Three are near the DAC, and the other is
on a distant corner.

If your A5 controller board has these capacitors, you
must replace them before anything else the scope does
will make much sense... Assuming that they haven't been
replaced already.

-Chuck Harris



peter bunge wrote:
Thanks Chuck, I was following the signal path from the two Intensity
pots
on the 2467B schematic, sheets 5 and 2. They do not go to an ADC input
but
I'm sure they must. There is something missing on the schematic, and I
have
looked at several.
Do you know what capacitors are referred to in this post:
Did you solve the capacitor leak problem on A5 logic board? Cause all
settings are under dependance of the DAC and when resistor connections
are
corroded everything goes wrong, including display points appearing, and
intensity dimming.






Re: Tek 2467B Erratic Intensity controls

Chuck Harris
 

Hi Siggi,

Yes, I keep forgetting they did that. Putting a
cheap little LM311 on the A5 board simplifies the
circuit board routing greatly, and keeps the noise down.

The trigger hybrid is used as the comparator for
anything related to parametric measurements... and,
well the trigger.

I don't think I have ever seen that LM311 go bad...

Thanks for keeping me honest.

-Chuck Harris

Siggi wrote:

The comparator U2510, an LM311, is used to compare the DAC output to pot
readings, and the MPU uses this with successive approximation to make a
software ADC. This is described in the “Theory of Operation” section.

The trigger hybrid is not involved in pot scanning, though otherwise it
works the way Chuck describes it.

On Sat, Nov 30, 2019 at 04:49 Chuck Harris <cfharris@...> wrote:

There is no ADC part in the 2465 family scopes.

There is a DAC that is used as a part of an ADC
that is made from the DAC, CPU, MUX's, Sample and
Hold cells, and the trigger hybrid. The trigger
hybrid is used as the comparator that compares the
DAC output to the pot's wiper voltage.

The voltages get to the trigger hybrid by way of
a pair of muxes.


WTB 7854 A29 Display Board

Fred S.
 

My 7854 is a real nightmare. The computer did not boot up, caused by most of the LV supplies being about 10% low. The op-amp for the 50V supply was the culprit.
After the repair, the scope worked on the bench just fine. Closed it up and put it back in its location and it stopped booting again. The all voltages are fine this time, but I noticed
when pushing the A29 display board, I will boot up. I cleaned all connectors and it will boot most of the time, but no more readout, system messages, or stored waveforms.
Since I don't have an extender board, I would like to buy an replacement.


--
Best regards,

Fred S.


Re: 577 VERTICAL (Current/div) selector dead increments

NigelP
 

A good blast of switch-cleaner/IPA on all wafers while rotating the shaft might help.

Regards

Nigel


Re: Tek 2467B Erratic Intensity controls

Siggi
 

The comparator U2510, an LM311, is used to compare the DAC output to pot
readings, and the MPU uses this with successive approximation to make a
software ADC. This is described in the “Theory of Operation” section.

The trigger hybrid is not involved in pot scanning, though otherwise it
works the way Chuck describes it.

On Sat, Nov 30, 2019 at 04:49 Chuck Harris <cfharris@...> wrote:

There is no ADC part in the 2465 family scopes.

There is a DAC that is used as a part of an ADC
that is made from the DAC, CPU, MUX's, Sample and
Hold cells, and the trigger hybrid. The trigger
hybrid is used as the comparator that compares the
DAC output to the pot's wiper voltage.

The voltages get to the trigger hybrid by way of
a pair of muxes.

The capacitors referred to in the post are on the
A5 controller card on scopes with serial numbers
greater than B049999.

They are ordinary power supply bypass capacitors,
that because of the abuse of their being soldered
to the board by an oven, leak electrolyte all over
themselves, and the circuit board. The electrolyte
is highly corrosive to copper, and highly conductive
to electricity. It eats the copper traces, and
shorts out other components and traces.

They are the only surface mount electrolytic capacitors
on the board. Three are near the DAC, and the other is
on a distant corner.

If your A5 controller board has these capacitors, you
must replace them before anything else the scope does
will make much sense... Assuming that they haven't been
replaced already.

-Chuck Harris



peter bunge wrote:
Thanks Chuck, I was following the signal path from the two Intensity pots
on the 2467B schematic, sheets 5 and 2. They do not go to an ADC input
but
I'm sure they must. There is something missing on the schematic, and I
have
looked at several.
Do you know what capacitors are referred to in this post:
Did you solve the capacitor leak problem on A5 logic board? Cause all
settings are under dependance of the DAC and when resistor connections
are
corroded everything goes wrong, including display points appearing, and
intensity dimming.




Re: Tek 2467B Erratic Intensity controls

Chuck Harris
 

There is no ADC part in the 2465 family scopes.

There is a DAC that is used as a part of an ADC
that is made from the DAC, CPU, MUX's, Sample and
Hold cells, and the trigger hybrid. The trigger
hybrid is used as the comparator that compares the
DAC output to the pot's wiper voltage.

The voltages get to the trigger hybrid by way of
a pair of muxes.

The capacitors referred to in the post are on the
A5 controller card on scopes with serial numbers
greater than B049999.

They are ordinary power supply bypass capacitors,
that because of the abuse of their being soldered
to the board by an oven, leak electrolyte all over
themselves, and the circuit board. The electrolyte
is highly corrosive to copper, and highly conductive
to electricity. It eats the copper traces, and
shorts out other components and traces.

They are the only surface mount electrolytic capacitors
on the board. Three are near the DAC, and the other is
on a distant corner.

If your A5 controller board has these capacitors, you
must replace them before anything else the scope does
will make much sense... Assuming that they haven't been
replaced already.

-Chuck Harris



peter bunge wrote:

Thanks Chuck, I was following the signal path from the two Intensity pots
on the 2467B schematic, sheets 5 and 2. They do not go to an ADC input but
I'm sure they must. There is something missing on the schematic, and I have
looked at several.
Do you know what capacitors are referred to in this post:
Did you solve the capacitor leak problem on A5 logic board? Cause all
settings are under dependance of the DAC and when resistor connections are
corroded everything goes wrong, including display points appearing, and
intensity dimming.


577 AC collector supply not reading zero on display

DW
 

With the collector supply set to AC, the collector voltage set to 0 volts, and particularly with a lower volts / division selection (1V, 0.5V) I notice a horizontal line about 1 division wide appearing across the the display as if the collector supply isn't quite going to zero. Is there an adjustment to compensate for this? The line becomes a dot in either + or - collector polarity. The line becomes longer in length when selecting higher collector voltages in AC.

Thanks


Re: 577 VERTICAL (Current/div) selector dead increments

DW
 

Recently I took apart the 177 test fixture to look at the current division switch, I found on the bottom of the switch there are small metal finger contacts that make contact with a mechanical bar that moves with the shaft of the switch. From what I could tell initially, at least from the bottom of the switch the metal fingers appeared to be making contact. The switch appears to be several layers thick. I will have to look more carefully as perhaps some of the hard to see areas of the switch might reveal some failed contact fingers.


Re: Tek 2467B Erratic Intensity controls

peter bunge
 

Thanks Chuck, I was following the signal path from the two Intensity pots
on the 2467B schematic, sheets 5 and 2. They do not go to an ADC input but
I'm sure they must. There is something missing on the schematic, and I have
looked at several.
Do you know what capacitors are referred to in this post:
Did you solve the capacitor leak problem on A5 logic board? Cause all
settings are under dependance of the DAC and when resistor connections are
corroded everything goes wrong, including display points appearing, and
intensity dimming.

On Fri, Nov 29, 2019 at 4:57 PM Chuck Harris <cfharris@...> wrote:

Hi Peter,

The 2465 creates an ADC function by using the DAC in concert with
MUX's, Sample-and-hold cells, and the trigger hybrid.

The CPU sets up the Mux to connect the DAC, and a sample and hold
gate to drive the DC trigger threshold input of the trigger hybrid.

The CPU adjusts the trigger threshold until the trigger hybrid just
switches from being less than to being more than the voltage being
measured when the CPU increments the DAC one count.

Tricky, but it was cheap and reliable for the times.

I'm not sure what you mean by a discriminator.

-Chuck Harris

peter bunge wrote:
Very confusing. The pot voltages are shown on sheet 5 going to sheet 2
into
the analog mux U2510, then through a discriminator? U2510 to a digital
mux
U2220. It is not shown going to an ADC so how does the CPU know what the
values are?
Jumping to the O/P side shown on sheet 2: the O/P of DAC U2101 goes
through analog mux U2530 to amplifiers U2630 then back in through sheet 5
to pins 22 & 23 of the sequencer U650.

Where and what is U950 referred to in the forum to check and clean its
contacts?



On Fri, Nov 29, 2019 at 11:30 AM peter bunge via Groups.Io <bunge.pjp=
gmail.com@groups.io> wrote:

I just found pdf service manuals from Artekmedia and Didier Juges
confirming where the Intensity controls connect.
I would like to buy a printed original manual.
What would delay the voltages to pins 22 & 23 of U650? Can U650 do that
and
yet other controls work (position etc)?

On Fri, Nov 29, 2019 at 10:23 AM peter bunge via Groups.Io <bunge.pjp=
gmail.com@groups.io> wrote:

My Tek 2467B has just started acting up. The Intensity and Readout
Intensity controls suddenly started to be erratic. The voltages to U650
sequencer are delayed by several seconds but can be set to useable
settings, however if changed the trace and/or readouts can suddenly
vanish.
If slowly adjusted to normal intensity and left alone the scope behaves
indefinitely (not a timeout problem).

I have the service manual for the 2465 but have not been able to find
one
for the 2467B. Does anyone have one?

The Intensity pot voltages from the 2467B are different from the 2465
and
the 2465 manual.
Intensity ccw 0V to 1.365V cw (2467B)
ccw 0V to 4.55V cw (2465)
Readout Intensity ccw 1.365V to -1.252V cw (2467B) ccw -5V
to
+5V cw (2465)
I searched this forum and apparently the manual and the 2465 that I
have
has the intensity pots wired to the U650. My 2467B is wired to the CPU
and
drives U650 from DACs?

The 2467B has a small vertically mounted board near the U650 that I
suspect has something to do with the Intensity and possibly the timed
turn
off that the 2465 does not have.

I suspect either U650 or the NOVRAM battery. I could replace U650 with
a
155 0244 00 from a 2465 but the 2467 is 155 0244 01 and I suspect they
may
not be the same because of the timed Bright-eye control. Are they
interchangeable?

I saw in the forum something else to check: “Did you try cleaning the
contacts on the old U950 and re-insert it? My 2467 was all kinds of
glitchy
and twichy, misbehaving in all kinds of ways until I cleaned and
re-seated
the hybrids”.
I am reluctant to disturb this component and cause another problem.

Any suggestions?
PeterB










Re: Tek 2467B Erratic Intensity controls

peter bunge
 

With a slightly bright display the timer shows 6M and counts down to 1M
then 59 secs down to 2 sec but instead of the display turning off the timer
resets to 9M and starts again.
The NOVRAM now seems unlikely to be the problem.
I will take a look at the (from forum):
Did you solve the capacitor leak problem on A5 logic board? Cause all
settings are under dependance of the DAC and when resistor connections are
corroded everything goes wrong, including display points appearing, and
intensity dimming.

On Fri, Nov 29, 2019 at 1:16 PM peter bunge via Groups.Io <bunge.pjp=
gmail.com@groups.io> wrote:

Very confusing. The pot voltages are shown on sheet 5 going to sheet 2 into
the analog mux U2510, then through a discriminator? U2510 to a digital mux
U2220. It is not shown going to an ADC so how does the CPU know what the
values are?
Jumping to the O/P side shown on sheet 2: the O/P of DAC U2101 goes
through analog mux U2530 to amplifiers U2630 then back in through sheet 5
to pins 22 & 23 of the sequencer U650.

Where and what is U950 referred to in the forum to check and clean its
contacts?



On Fri, Nov 29, 2019 at 11:30 AM peter bunge via Groups.Io <bunge.pjp=
gmail.com@groups.io> wrote:

I just found pdf service manuals from Artekmedia and Didier Juges
confirming where the Intensity controls connect.
I would like to buy a printed original manual.
What would delay the voltages to pins 22 & 23 of U650? Can U650 do that
and
yet other controls work (position etc)?

On Fri, Nov 29, 2019 at 10:23 AM peter bunge via Groups.Io <bunge.pjp=
gmail.com@groups.io> wrote:

My Tek 2467B has just started acting up. The Intensity and Readout
Intensity controls suddenly started to be erratic. The voltages to U650
sequencer are delayed by several seconds but can be set to useable
settings, however if changed the trace and/or readouts can suddenly
vanish.
If slowly adjusted to normal intensity and left alone the scope behaves
indefinitely (not a timeout problem).

I have the service manual for the 2465 but have not been able to find
one
for the 2467B. Does anyone have one?

The Intensity pot voltages from the 2467B are different from the 2465
and
the 2465 manual.
Intensity ccw 0V to 1.365V cw (2467B)
ccw 0V to 4.55V cw (2465)
Readout Intensity ccw 1.365V to -1.252V cw (2467B) ccw -5V
to
+5V cw (2465)
I searched this forum and apparently the manual and the 2465 that I
have
has the intensity pots wired to the U650. My 2467B is wired to the CPU
and
drives U650 from DACs?

The 2467B has a small vertically mounted board near the U650 that I
suspect has something to do with the Intensity and possibly the timed
turn
off that the 2465 does not have.

I suspect either U650 or the NOVRAM battery. I could replace U650 with
a
155 0244 00 from a 2465 but the 2467 is 155 0244 01 and I suspect they
may
not be the same because of the timed Bright-eye control. Are they
interchangeable?

I saw in the forum something else to check: “Did you try cleaning the
contacts on the old U950 and re-insert it? My 2467 was all kinds of
glitchy
and twichy, misbehaving in all kinds of ways until I cleaned and
re-seated
the hybrids”.
I am reluctant to disturb this component and cause another problem.

Any suggestions?
PeterB








Re: Tek 2467B Erratic Intensity controls

Chuck Harris
 

Hi Peter,

The 2465 creates an ADC function by using the DAC in concert with
MUX's, Sample-and-hold cells, and the trigger hybrid.

The CPU sets up the Mux to connect the DAC, and a sample and hold
gate to drive the DC trigger threshold input of the trigger hybrid.

The CPU adjusts the trigger threshold until the trigger hybrid just
switches from being less than to being more than the voltage being
measured when the CPU increments the DAC one count.

Tricky, but it was cheap and reliable for the times.

I'm not sure what you mean by a discriminator.

-Chuck Harris

peter bunge wrote:

Very confusing. The pot voltages are shown on sheet 5 going to sheet 2 into
the analog mux U2510, then through a discriminator? U2510 to a digital mux
U2220. It is not shown going to an ADC so how does the CPU know what the
values are?
Jumping to the O/P side shown on sheet 2: the O/P of DAC U2101 goes
through analog mux U2530 to amplifiers U2630 then back in through sheet 5
to pins 22 & 23 of the sequencer U650.

Where and what is U950 referred to in the forum to check and clean its
contacts?



On Fri, Nov 29, 2019 at 11:30 AM peter bunge via Groups.Io <bunge.pjp=
gmail.com@groups.io> wrote:

I just found pdf service manuals from Artekmedia and Didier Juges
confirming where the Intensity controls connect.
I would like to buy a printed original manual.
What would delay the voltages to pins 22 & 23 of U650? Can U650 do that and
yet other controls work (position etc)?

On Fri, Nov 29, 2019 at 10:23 AM peter bunge via Groups.Io <bunge.pjp=
gmail.com@groups.io> wrote:

My Tek 2467B has just started acting up. The Intensity and Readout
Intensity controls suddenly started to be erratic. The voltages to U650
sequencer are delayed by several seconds but can be set to useable
settings, however if changed the trace and/or readouts can suddenly
vanish.
If slowly adjusted to normal intensity and left alone the scope behaves
indefinitely (not a timeout problem).

I have the service manual for the 2465 but have not been able to find one
for the 2467B. Does anyone have one?

The Intensity pot voltages from the 2467B are different from the 2465 and
the 2465 manual.
Intensity ccw 0V to 1.365V cw (2467B)
ccw 0V to 4.55V cw (2465)
Readout Intensity ccw 1.365V to -1.252V cw (2467B) ccw -5V
to
+5V cw (2465)
I searched this forum and apparently the manual and the 2465 that I have
has the intensity pots wired to the U650. My 2467B is wired to the CPU
and
drives U650 from DACs?

The 2467B has a small vertically mounted board near the U650 that I
suspect has something to do with the Intensity and possibly the timed
turn
off that the 2465 does not have.

I suspect either U650 or the NOVRAM battery. I could replace U650 with a
155 0244 00 from a 2465 but the 2467 is 155 0244 01 and I suspect they
may
not be the same because of the timed Bright-eye control. Are they
interchangeable?

I saw in the forum something else to check: “Did you try cleaning the
contacts on the old U950 and re-insert it? My 2467 was all kinds of
glitchy
and twichy, misbehaving in all kinds of ways until I cleaned and
re-seated
the hybrids”.
I am reluctant to disturb this component and cause another problem.

Any suggestions?
PeterB








Re: Tek 2467B Erratic Intensity controls

peter bunge
 

Very confusing. The pot voltages are shown on sheet 5 going to sheet 2 into
the analog mux U2510, then through a discriminator? U2510 to a digital mux
U2220. It is not shown going to an ADC so how does the CPU know what the
values are?
Jumping to the O/P side shown on sheet 2: the O/P of DAC U2101 goes
through analog mux U2530 to amplifiers U2630 then back in through sheet 5
to pins 22 & 23 of the sequencer U650.

Where and what is U950 referred to in the forum to check and clean its
contacts?



On Fri, Nov 29, 2019 at 11:30 AM peter bunge via Groups.Io <bunge.pjp=
gmail.com@groups.io> wrote:

I just found pdf service manuals from Artekmedia and Didier Juges
confirming where the Intensity controls connect.
I would like to buy a printed original manual.
What would delay the voltages to pins 22 & 23 of U650? Can U650 do that and
yet other controls work (position etc)?

On Fri, Nov 29, 2019 at 10:23 AM peter bunge via Groups.Io <bunge.pjp=
gmail.com@groups.io> wrote:

My Tek 2467B has just started acting up. The Intensity and Readout
Intensity controls suddenly started to be erratic. The voltages to U650
sequencer are delayed by several seconds but can be set to useable
settings, however if changed the trace and/or readouts can suddenly
vanish.
If slowly adjusted to normal intensity and left alone the scope behaves
indefinitely (not a timeout problem).

I have the service manual for the 2465 but have not been able to find one
for the 2467B. Does anyone have one?

The Intensity pot voltages from the 2467B are different from the 2465 and
the 2465 manual.
Intensity ccw 0V to 1.365V cw (2467B)
ccw 0V to 4.55V cw (2465)
Readout Intensity ccw 1.365V to -1.252V cw (2467B) ccw -5V
to
+5V cw (2465)
I searched this forum and apparently the manual and the 2465 that I have
has the intensity pots wired to the U650. My 2467B is wired to the CPU
and
drives U650 from DACs?

The 2467B has a small vertically mounted board near the U650 that I
suspect has something to do with the Intensity and possibly the timed
turn
off that the 2465 does not have.

I suspect either U650 or the NOVRAM battery. I could replace U650 with a
155 0244 00 from a 2465 but the 2467 is 155 0244 01 and I suspect they
may
not be the same because of the timed Bright-eye control. Are they
interchangeable?

I saw in the forum something else to check: “Did you try cleaning the
contacts on the old U950 and re-insert it? My 2467 was all kinds of
glitchy
and twichy, misbehaving in all kinds of ways until I cleaned and
re-seated
the hybrids”.
I am reluctant to disturb this component and cause another problem.

Any suggestions?
PeterB






Re: Tek 2467B Erratic Intensity controls

peter bunge
 

I just found pdf service manuals from Artekmedia and Didier Juges
confirming where the Intensity controls connect.
I would like to buy a printed original manual.
What would delay the voltages to pins 22 & 23 of U650? Can U650 do that and
yet other controls work (position etc)?

On Fri, Nov 29, 2019 at 10:23 AM peter bunge via Groups.Io <bunge.pjp=
gmail.com@groups.io> wrote:

My Tek 2467B has just started acting up. The Intensity and Readout
Intensity controls suddenly started to be erratic. The voltages to U650
sequencer are delayed by several seconds but can be set to useable
settings, however if changed the trace and/or readouts can suddenly vanish.
If slowly adjusted to normal intensity and left alone the scope behaves
indefinitely (not a timeout problem).

I have the service manual for the 2465 but have not been able to find one
for the 2467B. Does anyone have one?

The Intensity pot voltages from the 2467B are different from the 2465 and
the 2465 manual.
Intensity ccw 0V to 1.365V cw (2467B)
ccw 0V to 4.55V cw (2465)
Readout Intensity ccw 1.365V to -1.252V cw (2467B) ccw -5V to
+5V cw (2465)
I searched this forum and apparently the manual and the 2465 that I have
has the intensity pots wired to the U650. My 2467B is wired to the CPU and
drives U650 from DACs?

The 2467B has a small vertically mounted board near the U650 that I
suspect has something to do with the Intensity and possibly the timed turn
off that the 2465 does not have.

I suspect either U650 or the NOVRAM battery. I could replace U650 with a
155 0244 00 from a 2465 but the 2467 is 155 0244 01 and I suspect they may
not be the same because of the timed Bright-eye control. Are they
interchangeable?

I saw in the forum something else to check: “Did you try cleaning the
contacts on the old U950 and re-insert it? My 2467 was all kinds of glitchy
and twichy, misbehaving in all kinds of ways until I cleaned and re-seated
the hybrids”.
I am reluctant to disturb this component and cause another problem.

Any suggestions?
PeterB




Tek 2467B Erratic Intensity controls

peter bunge
 

My Tek 2467B has just started acting up. The Intensity and Readout Intensity controls suddenly started to be erratic. The voltages to U650 sequencer are delayed by several seconds but can be set to useable settings, however if changed the trace and/or readouts can suddenly vanish. If slowly adjusted to normal intensity and left alone the scope behaves indefinitely (not a timeout problem).

I have the service manual for the 2465 but have not been able to find one for the 2467B. Does anyone have one?

The Intensity pot voltages from the 2467B are different from the 2465 and the 2465 manual.
Intensity ccw 0V to 1.365V cw (2467B) ccw 0V to 4.55V cw (2465)
Readout Intensity ccw 1.365V to -1.252V cw (2467B) ccw -5V to +5V cw (2465)
I searched this forum and apparently the manual and the 2465 that I have has the intensity pots wired to the U650. My 2467B is wired to the CPU and drives U650 from DACs?

The 2467B has a small vertically mounted board near the U650 that I suspect has something to do with the Intensity and possibly the timed turn off that the 2465 does not have.

I suspect either U650 or the NOVRAM battery. I could replace U650 with a 155 0244 00 from a 2465 but the 2467 is 155 0244 01 and I suspect they may not be the same because of the timed Bright-eye control. Are they interchangeable?

I saw in the forum something else to check: “Did you try cleaning the contacts on the old U950 and re-insert it? My 2467 was all kinds of glitchy and twichy, misbehaving in all kinds of ways until I cleaned and re-seated the hybrids”.
I am reluctant to disturb this component and cause another problem.

Any suggestions?
PeterB


Re: HV curve tracer project - need info on vacuum tube X-ray shielding

 

Hi Ed,

I have no idea what you are trying to accomplish and you seem to be determined to make this work a certain way. If that is the case you can spare us from making further suggestions.

It sounds like, to me, what you want is a high voltage capacitor of only a few pico Farads. If that is the case it is trivially simple to make a HV capacitor of any value you want instead of trying to do it your way and worrying about X-ray side effects.

This video will give you the general idea of how simple this is:
https://hackaday.com/2015/08/02/homemade-high-voltage-caps/

Dennis Tillman W7PF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Ed Breya via Groups.Io
Sent: Thursday, November 28, 2019 12:00 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] HV curve tracer project - need info on vacuum tube X-ray shielding

It's no good again. I discovered a fatal flaw in my test setup. The plate cap lead that I used had a break in the wire inside the insulation, so the tube was not actually hooked up. I was happily going along with experiments and advancing the design, until I found the plate lead folded right over way too easily - a bad sign. When I checked it out and fixed it, the rectification current was there, about the same or worse than with the 1X2. The bottom line is that all these HV rectifiers are no good for general use as vacuum caps. They could work in situations where the plate is negative with respect to the cathode, but not in the forward direction. Oh well, back to the gimmick cap - at least it's very small.

Ed




--
Dennis Tillman W7PF
TekScopes Moderator


Re: Tektronix 7904, no horizontal trace on input B

Hermansson Amplification
 

When I switch between horizontal mode A and B and measures the voltage of pin 7 and pin 10 (of the U305) they switches between 0V and 5V. It’s the same regardless if I have the 7B92A in slot A or slot B.
Does the data in my previous post give you any idea if the U305 work as it should or not?


Re: Free equipment for pickup noon Saturday, Nov. 30, Los Angeles area

DaveH52
 

I'd like to get the Siglent scope, and the HP 8591. Would you ship them to NJ if I pay the shipping and for your trouble?


Re: Tektronix TX1---tx2

hardyhansendk
 

Thanks Håkan
I might make one myself
Regards
Hardy

-----Oprindelig meddelelse-----
Fra: TekScopes@groups.io [mailto:TekScopes@groups.io] På vegne af zenith5106
Sendt: 27. november 2019 22:54
Til: TekScopes@groups.io
Emne: Re: [TekScopes] Tektronix TX1---tx2

On Wed, Nov 27, 2019 at 01:16 PM, hardyhansendk wrote:


even a parts nr could help!
Tek P/N for the blue Protective Boot standard accessory is 650-3681-xx.
Since Tek sold the TX series to Fluke who renamed TX1 and TX3
to 183 and 185 you might also find it at Fluke but then it is yellow.

/Håkan


Re: HV curve tracer project - need info on vacuum tube X-ray shielding

 

OK Ed, you have piqued my curiosity! What do you want to curve trace at Anode/Collector/Drain voltages of 7.5kV ?

Cheers
David

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Ed Breya via Groups.Io
Sent: 28 November 2019 08:00
To: TekScopes@groups.io
Subject: Re: [TekScopes] HV curve tracer project - need info on vacuum tube X-ray shielding

It's no good again. I discovered a fatal flaw in my test setup. The plate cap lead that I used had a break in the wire inside the insulation, so the tube was not actually hooked up. I was happily going along with experiments and advancing the design, until I found the plate lead folded right over way too easily - a bad sign. When I checked it out and fixed it, the rectification current was there, about the same or worse than with the 1X2. The bottom line is that all these HV rectifiers are no good for general use as vacuum caps. They could work in situations where the plate is negative with respect to the cathode, but not in the forward direction. Oh well, back to the gimmick cap - at least it's very small.

Ed


Re: HV curve tracer project - need info on vacuum tube X-ray shielding

Ed Breya
 

It's no good again. I discovered a fatal flaw in my test setup. The plate cap lead that I used had a break in the wire inside the insulation, so the tube was not actually hooked up. I was happily going along with experiments and advancing the design, until I found the plate lead folded right over way too easily - a bad sign. When I checked it out and fixed it, the rectification current was there, about the same or worse than with the 1X2. The bottom line is that all these HV rectifiers are no good for general use as vacuum caps. They could work in situations where the plate is negative with respect to the cathode, but not in the forward direction. Oh well, back to the gimmick cap - at least it's very small.

Ed