Date   
Re: 114xx bezzel buttons

Renée
 

I will delete mine since it is a "borrowed " copy and not properly acquired.
Renée

On 2018-07-07 08:12 AM, Pete Lancashire wrote:
I want to say at the scan on Bama is from Artek. I used to provide them
with very rare tektronix manuals to be scanned.

They spend many many hours cleaning up Originals making sure things are
aligned excetera excetera

They asked very little for a copy to see it on Bama makes me want to throw
up.

And makes me want to decide the other 40 or 50 tektronix manuals that exist
nowhere else will be thrown out instead.

On Sat, Jul 7, 2018, 8:10 AM Renée <@rjdeeter> wrote:

that works.....Thank you...now I can follow along
Renée

On 2018-07-07 02:45 AM, Michael A. Terrell wrote:
That link should redirect to:

https://bama.edebris.com/download/tek/11403a/11403A_SM.pdf


Michael A. Terrell


-----Original Message-----
From: Renée <@rjdeeter>

service manual is 404 for me as well..broken.
The user reference is fine...link works
Renée

On 2018-07-06 11:04 PM, tmillermdems wrote:
The link works fine.

The .pdf manual is here.

http://w140.com/11403A_SM.pdf


Re: Kludging together a TDR or similar?

 

On Sat, Jul 7, 2018 at 07:15 am, Michael A. Terrell wrote:


The time required for a pulse to travel to the discontinuity isn't affected by
the error in the pulse width. If it bothers you, use a crystal time base
instead of a simple one gate oscillator.
The oscillator's period (better: interval between pulses) must be long enough to avoid overlapping between edges and echos and short enough for a bright, non-flickering image, if you're using a non-storage, analog 'scope. Usually, there's a world of time between the two. A shorter interval results in a brighter image because of the larger duty-cycle of 'scope traces.

Raymond

Re: SC504 Gain Knob Removal

tom jobe <tomjobe@...>
 

Okay, I will make one more attempt at this explanation.
This morning I went back to the same SC504 that I played with yesterday.
I removed the small knob and 1/8" shaft assembly that goes through that same channel switch knob I freed up yesterday.
The main knob will almost fall in and out of the scope, but you can feel a very light detent action which probably happens at that groove you speak of.
The aluminum washer I mentioned cannot be seen until the main knob comes out part of the way, as the washer sits on the step of the knob's extension where the diameter changes from just under .250" to a little under .300". The hole in the front face plate will barely let the aluminum washer through, so it might get pulled off and missed if you are not watching all of this from the side.
As for how I 'pried' on the knob yesterday: I pulled and wiggled on the knob and got it to move outward maybe 1/8" extra, but then it would not move any more, so I used a small flat blade screwdriver to reach in from the closest edge of the front face (which I used as a leverage point) to apply a steady outward force while I wiggled and pulled on the knob.
Where the actual sticking point was, or what caused the problem are all unknown to me.
You say this is a high risk task. I felt the same way as I tried to find you an answer with my perfectly good parts.
Best of luck!
tom jobe...

On 7/6/2018 11:41 PM, Larry McDavid wrote:
Thanks, Tom, for this reply, the only one I received.

I did loosen the knob set screw and remove the red VAR knob. My replacement skirted knob does have a long shaft that goes through some kind of (cam") switch near the front panel but it seems to have no means obvious to secure it inside the scope.

I did not even think of removing the small diameter plastic shaft to which the red VAR knob is attached. I just now loosened the set screw in the aluminum collar on the pot to which the plastic rod is attached and easily removed the red VAR knob and its shaft. I tugged as much as I thought wise and the skirted knob still did not come out.

The shaft on the replacement knob is long enough to enter the gray plastic collar that protrudes forward from the cam switch. Rotating the skirted knob, I see no screw to secure that knob shaft. I'm still puzzled.

I note the replacement knob has a shallow "V" groove that ends up somewhere inside the other (cam?) switch close to the front panel. Maybe there is some kind of detent spring inside that switch; I can't take that switch apart because I'd need to remove the bottom panel or side beam and I surely don't want to do that.

The red VAR knob and its shaft would hold the skirted knob in well enough but it might rub on the front panel without something to position it. The tolerances make the "V" groove seem unlikely to be what positions the knob. I don't see the thin washer you describe. Tell me again where that is located, please.

What do you mean by "...pried and pulled" to get the knob back out after first putting it back in? Pry? On what?

This seems like a high-risk task! But, that one knob has damaged nomenclature on the skirt and I was able to buy the exact replacement knob on eBay.

The interior of the end of the skirted knob shaft has some details that engage the shaft inside that switch thing near the front panel. That detail will keep the knob clocked but can't hold it in. It may be that shallow "V" groove that holds the knob in.

I surely don't want to damage something inside the cam switch or that other switch near the front panel. And, I really don't want to dribble anything down the skirted knob shaft in hopes of getting to that "V" groove.

I'm feeling kinda stymied...

By the way, I'm a mechanical engineer with a lifetime of small, precision instrumentation design. I'm not intimidated by this problem, just really cautious!

I'm in Anaheim, California, near Disneyland. Good Grief! It was 115.1°F here this afternoon!

Larry




On 7/6/2018 4:18 PM, tom jobe wrote:
Hi Larry,
Your question got me wondering about this, so I took the side cover off of an SC504 to have a look.
The service manual mechanical parts diagram shows the knob has a longer part that goes back into the Channel switch so I looked to see if there was a screw or other fastening device back inside of the scope. I removed the plastic rod that goes through the knob assembly by disconnecting it at the aluminum collar on the VAR switch, and then the knob just fell out for some reason. I put the knob back in and then it would not come out again. So I nervously pried and pulled and got it back out again without damaging it.
A study of the knob shaft showed no locking mechanisms of any kind, so I rubbed a very thin smear of Johnson's paste wax on the knob shaft extension and put it back in. After that the knob slid in and out nicely and the only thing holding the knob in is the 1/8" fiberglass VAR shaft and small VAR knob in the center of the knob in question.
I guess the knob was just stuck from being in there for 30 or 40 years plastic on plastic?
Do be careful about a very thin aluminum washer that is on the knob's rear shaft extension, as it would be very easy to drop that washer into the scope. My guess is that this washer is part of the spacing arrangement that keeps the lettering on the back side of the knob skirt from hitting the front panel and getting damaged, and it also might keep the two plastic parts from rubbing on each other at the knob extension / attenuator surfaces?
tom jobe...
PS I wonder if one drop of water could be put in from the side where the knob shaft extension goes into the attenuator assembly to break it free as you wiggled the knob to spread it around? You would want to be very careful about anything you put in there, as the short and long term effects on the plastic parts could be devastating.





On 7/6/2018 11:30 AM, Larry McDavid wrote:
I have a SC504 scope module with a damaged Channel 1 knob skirt and I have a Tek replacement skirted knob. I can remove the small red central knob by loosening a set screw.

How is the skirted knob removed? I've tried gently pulling on it without success. The knob has a long plastic shaft with some internal ribs to fit over another shaft but I don't know how the knob is attached.

Anyone done this?




Re: 114xx bezzel buttons

Pete Lancashire
 

Sent.



On Sat, Jul 7, 2018 at 8:22 AM Michael A. Terrell <
mike.terrell@...> wrote:

Have you asked the site owner to remove it? He may not know where it came
from, since the site was intended for old ham radio manuals.


Michael A. Terrell


-----Original Message-----
From: Pete Lancashire <xyzzypdx@...>
Sent: Jul 7, 2018 11:12 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] 114xx bezzel buttons

I want to say at the scan on Bama is from Artek. I used to provide them
with very rare tektronix manuals to be scanned.

They spend many many hours cleaning up Originals making sure things are
aligned excetera excetera

They asked very little for a copy to see it on Bama makes me want to throw
up.

And makes me want to decide the other 40 or 50 tektronix manuals that
exist
nowhere else will be thrown out instead.


Re: Kludging together a TDR or similar?

Michael A. Terrell
 

You're welcome.


Michael A. Terrell

-----Original Message-----
From: cheater cheater <@cheater>
Sent: Jul 7, 2018 10:48 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Kludging together a TDR or similar?

interesting design for a cheap tdr. thanks!

On Sat, 7 Jul 2018, 16:16 Michael A. Terrell, <mike.terrell@...>
wrote:

Both parts are 5% but that isn't important.

The time required for a pulse to travel to the discontinuity isn't
affected by the error in the pulse width. If it bothers you, use a crystal
time base instead of a simple one gate oscillator.

I have another schematic with multiple pulse widths that you can select
from, but like this design, it is built with 5% parts. That one also allows
you to select 50, 75 or 100 ohm output impedance by adding a 22 ohm, or a
50 ohm resistor in the output path.

Even temperature has some effect on the frequency, along with the
propagation delay on the gate.

Re: 114xx bezzel buttons

Michael A. Terrell
 

Have you asked the site owner to remove it? He may not know where it came from, since the site was intended for old ham radio manuals.


Michael A. Terrell

-----Original Message-----
From: Pete Lancashire <xyzzypdx@...>
Sent: Jul 7, 2018 11:12 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] 114xx bezzel buttons

I want to say at the scan on Bama is from Artek. I used to provide them
with very rare tektronix manuals to be scanned.

They spend many many hours cleaning up Originals making sure things are
aligned excetera excetera

They asked very little for a copy to see it on Bama makes me want to throw
up.

And makes me want to decide the other 40 or 50 tektronix manuals that exist
nowhere else will be thrown out instead.

Re: 114xx bezzel buttons

Pete Lancashire
 

I want to say at the scan on Bama is from Artek. I used to provide them
with very rare tektronix manuals to be scanned.

They spend many many hours cleaning up Originals making sure things are
aligned excetera excetera

They asked very little for a copy to see it on Bama makes me want to throw
up.

And makes me want to decide the other 40 or 50 tektronix manuals that exist
nowhere else will be thrown out instead.

On Sat, Jul 7, 2018, 8:10 AM Renée <@rjdeeter> wrote:

that works.....Thank you...now I can follow along
Renée

On 2018-07-07 02:45 AM, Michael A. Terrell wrote:
That link should redirect to:

https://bama.edebris.com/download/tek/11403a/11403A_SM.pdf


Michael A. Terrell


-----Original Message-----
From: Renée <@rjdeeter>

service manual is 404 for me as well..broken.
The user reference is fine...link works
Renée

On 2018-07-06 11:04 PM, tmillermdems wrote:
The link works fine.

The .pdf manual is here.

http://w140.com/11403A_SM.pdf




Re: 114xx bezzel buttons

Renée
 

that works.....Thank you...now I can follow along
Renée

On 2018-07-07 02:45 AM, Michael A. Terrell wrote:
That link should redirect to:

https://bama.edebris.com/download/tek/11403a/11403A_SM.pdf


Michael A. Terrell


-----Original Message-----
From: Renée <@rjdeeter>

service manual is 404 for me as well..broken.
The user reference is fine...link works
Renée

On 2018-07-06 11:04 PM, tmillermdems wrote:
The link works fine.

The .pdf manual is here.

http://w140.com/11403A_SM.pdf

Re: Kludging together a TDR or similar?

 

interesting design for a cheap tdr. thanks!

On Sat, 7 Jul 2018, 16:16 Michael A. Terrell, <mike.terrell@...>
wrote:

Both parts are 5% but that isn't important.

The time required for a pulse to travel to the discontinuity isn't
affected by the error in the pulse width. If it bothers you, use a crystal
time base instead of a simple one gate oscillator.

I have another schematic with multiple pulse widths that you can select
from, but like this design, it is built with 5% parts. That one also allows
you to select 50, 75 or 100 ohm output impedance by adding a 22 ohm, or a
50 ohm resistor in the output path.

Even temperature has some effect on the frequency, along with the
propagation delay on the gate.


Michael A. Terrell


-----Original Message-----
From: n4buq <n4buq@...>
Sent: Jul 7, 2018 9:03 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Kludging together a TDR or similar?

Looking at that schematic, it appears the frequency is determined by C3
and R1. If I'm not mistaken, the exact values of those components would
result in a frequency of 3.129 kHz; however, the oscilloscope images appear
to show 4.81 kHz. Is that difference due to component tolerances or is
something else at work here?

Thanks,
Barry - N4BUQ


Re: Kludging together a TDR or similar?

Michael A. Terrell
 

Both parts are 5% but that isn't important.

The time required for a pulse to travel to the discontinuity isn't affected by the error in the pulse width. If it bothers you, use a crystal time base instead of a simple one gate oscillator.

I have another schematic with multiple pulse widths that you can select from, but like this design, it is built with 5% parts. That one also allows you to select 50, 75 or 100 ohm output impedance by adding a 22 ohm, or a 50 ohm resistor in the output path.

Even temperature has some effect on the frequency, along with the propagation delay on the gate.


Michael A. Terrell

-----Original Message-----
From: n4buq <n4buq@...>
Sent: Jul 7, 2018 9:03 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Kludging together a TDR or similar?

Looking at that schematic, it appears the frequency is determined by C3 and R1. If I'm not mistaken, the exact values of those components would result in a frequency of 3.129 kHz; however, the oscilloscope images appear to show 4.81 kHz. Is that difference due to component tolerances or is something else at work here?

Thanks,
Barry - N4BUQ

Re: TDS744

Vintage Test
 

Guys,

Thanks very much for all of your help and the link to Hakan’s info - I’ll certainly have a look! I managed to do a deal with a US seller for a complete, working board(s), but will repair mine in case others might need it in the future. While looking for a replacement, I noticed that the later versions have a different HT trans former, so will look into this and get back to you all. Once again, many thanks.

--
you can never have enough oscilloscopes, DMMs, valve testers or soldering irons . . .

Re: Kludging together a TDR or similar?

Bruce Griffiths
 

Guessing isn't good enough, you need to analyse the circuit and take into account the hysteresis of the 74AC14 Schmitt trigger.

Bruce

On 08 July 2018 at 01:22 n4buq <n4buq@...> wrote:


Because I don't know what else is establishing the frequency (hence "...or is something else at work here?").

Thanks,
Barry - N4BUQ

----- Original Message -----
From: "Bruce Griffiths" <bruce.griffiths@...>
To: TekScopes@groups.io
Sent: Saturday, July 7, 2018 8:15:53 AM
Subject: Re: [TekScopes] Kludging together a TDR or similar?

Why do you think that the frequency is equal to 1/RC?
Bruce
On 08 July 2018 at 01:03 n4buq <n4buq@...> wrote:


Looking at that schematic, it appears the frequency is determined by C3 and
R1. If I'm not mistaken, the exact values of those components would
result in a frequency of 3.129 kHz; however, the oscilloscope images
appear to show 4.81 kHz. Is that difference due to component tolerances
or is something else at work here?

Thanks,
Barry - N4BUQ

----- Original Message -----
From: "Michael A. Terrell" <mike.terrell@...>
To: TekScopes@groups.io
Sent: Friday, July 6, 2018 7:32:15 PM
Subject: Re: [TekScopes] Kludging together a TDR or similar?

You can build a simple TDR with a 74AC14, some resistors and a couple
capacitors.
<http://nebula.wsimg.com/e68cc6277a9236e831f2cb6fe9b27819?AccessKeyId=13A6205A294059260963&disposition=0&alloworigin=1>

If that doesn't work, it is from this page:
http://www.electroresales.com/user-guides.html

It is sold on Ebay by <https://www.ebay.com/str/electroresales> It was
$15.19
a couple months ago. It isn't available right now. I bought one, to test.
If
I like it I will make a surface mount version of it, and put it into a
small
extruded aluminum box. The box, and the three connectors will be about
80%
of the component costs in a SMD version.



Michael A. Terrell


-----Original Message-----
From: cheater cheater <@cheater>
Sent: Jun 29, 2018 3:20 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Kludging together a TDR or similar?

hi guys, thanks for the replies.

I don't have the parts necessary to build a pulser. Can I use the
mainframe's pulse generator?

The cable goes from a local distribution box, part underground, part
overground, and then goes to a wall socket used only by my modem. There
is
no splitting and no neighbors using this. The run in my yard that is
overground is maybe 30m at most.

There was no thunder when this stopped working, just heavy rain.






Re: Kludging together a TDR or similar?

n4buq
 

Because I don't know what else is establishing the frequency (hence "...or is something else at work here?").

Thanks,
Barry - N4BUQ

----- Original Message -----
From: "Bruce Griffiths" <bruce.griffiths@...>
To: TekScopes@groups.io
Sent: Saturday, July 7, 2018 8:15:53 AM
Subject: Re: [TekScopes] Kludging together a TDR or similar?

Why do you think that the frequency is equal to 1/RC?
Bruce
On 08 July 2018 at 01:03 n4buq <n4buq@...> wrote:


Looking at that schematic, it appears the frequency is determined by C3 and
R1. If I'm not mistaken, the exact values of those components would
result in a frequency of 3.129 kHz; however, the oscilloscope images
appear to show 4.81 kHz. Is that difference due to component tolerances
or is something else at work here?

Thanks,
Barry - N4BUQ

----- Original Message -----
From: "Michael A. Terrell" <mike.terrell@...>
To: TekScopes@groups.io
Sent: Friday, July 6, 2018 7:32:15 PM
Subject: Re: [TekScopes] Kludging together a TDR or similar?

You can build a simple TDR with a 74AC14, some resistors and a couple
capacitors.
<http://nebula.wsimg.com/e68cc6277a9236e831f2cb6fe9b27819?AccessKeyId=13A6205A294059260963&disposition=0&alloworigin=1>

If that doesn't work, it is from this page:
http://www.electroresales.com/user-guides.html

It is sold on Ebay by <https://www.ebay.com/str/electroresales> It was
$15.19
a couple months ago. It isn't available right now. I bought one, to test.
If
I like it I will make a surface mount version of it, and put it into a
small
extruded aluminum box. The box, and the three connectors will be about
80%
of the component costs in a SMD version.



Michael A. Terrell


-----Original Message-----
From: cheater cheater <@cheater>
Sent: Jun 29, 2018 3:20 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Kludging together a TDR or similar?

hi guys, thanks for the replies.

I don't have the parts necessary to build a pulser. Can I use the
mainframe's pulse generator?

The cable goes from a local distribution box, part underground, part
overground, and then goes to a wall socket used only by my modem. There
is
no splitting and no neighbors using this. The run in my yard that is
overground is maybe 30m at most.

There was no thunder when this stopped working, just heavy rain.





Re: Kludging together a TDR or similar?

Bruce Griffiths
 

Why do you think that the frequency is equal to 1/RC?
Bruce

On 08 July 2018 at 01:03 n4buq <n4buq@...> wrote:


Looking at that schematic, it appears the frequency is determined by C3 and R1. If I'm not mistaken, the exact values of those components would result in a frequency of 3.129 kHz; however, the oscilloscope images appear to show 4.81 kHz. Is that difference due to component tolerances or is something else at work here?

Thanks,
Barry - N4BUQ

----- Original Message -----
From: "Michael A. Terrell" <mike.terrell@...>
To: TekScopes@groups.io
Sent: Friday, July 6, 2018 7:32:15 PM
Subject: Re: [TekScopes] Kludging together a TDR or similar?

You can build a simple TDR with a 74AC14, some resistors and a couple
capacitors.
<http://nebula.wsimg.com/e68cc6277a9236e831f2cb6fe9b27819?AccessKeyId=13A6205A294059260963&disposition=0&alloworigin=1>

If that doesn't work, it is from this page:
http://www.electroresales.com/user-guides.html

It is sold on Ebay by <https://www.ebay.com/str/electroresales> It was $15.19
a couple months ago. It isn't available right now. I bought one, to test. If
I like it I will make a surface mount version of it, and put it into a small
extruded aluminum box. The box, and the three connectors will be about 80%
of the component costs in a SMD version.



Michael A. Terrell


-----Original Message-----
From: cheater cheater <@cheater>
Sent: Jun 29, 2018 3:20 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Kludging together a TDR or similar?

hi guys, thanks for the replies.

I don't have the parts necessary to build a pulser. Can I use the
mainframe's pulse generator?

The cable goes from a local distribution box, part underground, part
overground, and then goes to a wall socket used only by my modem. There is
no splitting and no neighbors using this. The run in my yard that is
overground is maybe 30m at most.

There was no thunder when this stopped working, just heavy rain.



Re: Kludging together a TDR or similar?

n4buq
 

Looking at that schematic, it appears the frequency is determined by C3 and R1. If I'm not mistaken, the exact values of those components would result in a frequency of 3.129 kHz; however, the oscilloscope images appear to show 4.81 kHz. Is that difference due to component tolerances or is something else at work here?

Thanks,
Barry - N4BUQ

----- Original Message -----
From: "Michael A. Terrell" <mike.terrell@...>
To: TekScopes@groups.io
Sent: Friday, July 6, 2018 7:32:15 PM
Subject: Re: [TekScopes] Kludging together a TDR or similar?

You can build a simple TDR with a 74AC14, some resistors and a couple
capacitors.
<http://nebula.wsimg.com/e68cc6277a9236e831f2cb6fe9b27819?AccessKeyId=13A6205A294059260963&disposition=0&alloworigin=1>

If that doesn't work, it is from this page:
http://www.electroresales.com/user-guides.html

It is sold on Ebay by <https://www.ebay.com/str/electroresales> It was $15.19
a couple months ago. It isn't available right now. I bought one, to test. If
I like it I will make a surface mount version of it, and put it into a small
extruded aluminum box. The box, and the three connectors will be about 80%
of the component costs in a SMD version.



Michael A. Terrell


-----Original Message-----
From: cheater cheater <@cheater>
Sent: Jun 29, 2018 3:20 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Kludging together a TDR or similar?

hi guys, thanks for the replies.

I don't have the parts necessary to build a pulser. Can I use the
mainframe's pulse generator?

The cable goes from a local distribution box, part underground, part
overground, and then goes to a wall socket used only by my modem. There is
no splitting and no neighbors using this. The run in my yard that is
overground is maybe 30m at most.

There was no thunder when this stopped working, just heavy rain.


Re: Questions about TM mainframes with Option 2

PHB
 

Ah kay. Thanks for explaining. So, looking at the pinout in the 5A22 schematics, sure enough, it's totally different from the TM5000's receptacle wiring.

I guess it would be kind of tedious, but it seems like a DIY frame/chassis to house and power these 5Axx plugins could be constructed with the correctly keyed edge connector.

Oh well, thanks for the info! You saved me a lot of trouble. :)

Re: TDS744

Siggi
 

On Fri, Jul 6, 2018 at 18:37 Vintage Test via Groups.Io <mel.purcell=
icloud.com@groups.io> wrote:

I've just laid my hands on one of these for a decent price, knowing it
didn't work. The owner said it worked one day and jus did tick, tick etc
the next - a familiar story! When I stripped it, I found a load of duff
diodes/transistors and two-way devices in the standby circuit, which I
replaced. I powered it up - still the same, except that the front-panel
LEDs all flashed too now. On a whim, I disconnected everything from the
processor board, and lo and behold -it powered up and worked properly into
a VGA monitor. Now, to the problem; the CRT driver assembly is clearly
faulty, but there's no schematic for it anywhere. I have the manual for
TDS540, which has a lot of similarities, but is monochrome and not colour,
so the CRT driver assembly is way different. Do any of you happen to have
any experience with these 'scopes?

I did look for a schematic before I recapped the CRT driver in my TDS784D,
but at the time there wasn’t anything around that I could find. Since then,
Håkan has made this <
http://www.hakanh.com/dl/docs/hardtofind/TDS544A_A30-32(Disp).pdf>
available for download. Maybe it’ll help? There may be other relevant docs
on his site, he keeps adding stuff over time.

People also convert those to LCD screens. There’s the NewScope kit, but you
can also just drive an LCD from the VGA output.

Re: 114xx bezzel buttons

Michael A. Terrell
 

That link should redirect to:

https://bama.edebris.com/download/tek/11403a/11403A_SM.pdf


Michael A. Terrell

-----Original Message-----
From: Renée <@rjdeeter>

service manual is 404 for me as well..broken.
The user reference is fine...link works
Renée

On 2018-07-06 11:04 PM, tmillermdems wrote:
The link works fine.

The .pdf manual is here.

http://w140.com/11403A_SM.pdf

Re: 2215 avoiding future CRT damage

Vincent Trouilliez
 

On Fri, Jul 6, 2018 at 10:35 pm, John Kolb wrote:
The hold-off circuit introduces a delay between one sweep cycle and the next.
Thus the longer the delay, the less often the sweeps occur, which affects the
brightness. If the trace is bright with minimum hold-off, you should be in
good shape.
Thanks a lot John, in just a couple lines you managed to make it all limpid ! :-)

So looks like the Hold-off feature can be used to "select"/pick a particular event in a complex waveform. I now understand why someone advised me to fiddle with hold-off when I was trying to get a clear picture of the switched currents in the inverter of the SMSP of my 2232 scope, which I was fixing. There was a "current sense" resistor which was common to both windings, so I conveniently used it. Of course that meant that I would see the switched current of both windings on the same trace, "interleaved".

Without hold-off, the scope would trigger on both windings indistinctly, hence superimposing them on top of each other. Since the two currents did not have exactly the same amplitude, on the screen I would see a "double" waveform, as if the trace was unstable, which it was not then, just the two currents being "stacked" on one another. When I fiddled with hold-off I could get rid of the double waveform and "select" which of the two currents I wanted to see, and have only that one on the screen. Was great ! :-)

Sorry for the rambling/thinking out loud, but I like it so much when someone with just a few words can clarify something that's been obscure for so long ! ^^

Thanks :-)

Anyway, to get back on topic : looks like my CRT is not worn out, that's a big relief indeed...



Vincent Trouilliez

Re: 114xx bezzel buttons

Renée
 

service manual is 404 for me as well..broken.
The user reference is fine...link works
Renée

On 2018-07-06 11:04 PM, tmillermdems wrote:
The link works fine.

The .pdf manual is here.

http://w140.com/11403A_SM.pdf



----- Original Message ----- From: "Pete Lancashire" <xyzzypdx@...>
To: <TekScopes@groups.io>
Sent: Saturday, July 07, 2018 1:08 AM
Subject: Re: [TekScopes] 114xx bezzel buttons


I must be doing something wrong.  The reference to a service manual comes
up 404 for me. Please let me know what I am doing wrong and what page(s) I
should be looking at.

=pete

On Fri, Jul 6, 2018 at 8:03 PM <jbau@...> wrote:

There's a link to the manuals on the TekWiki site:
http://w140.com/tekwiki/wiki/11403