Date   

Re: TM5xx extenders

John Griessen
 

On 3/4/19 2:20 PM, bill K7WXW wrote:
John's version comes up as 404. Thanks, Bill
Yes, my TM500 extender kits are EOL, not being made again.

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


Re: 2465B vertical lines when readout is on

Siggi
 

On Sun, Mar 10, 2019 at 12:23 AM Dr. Bernd Burfeindt via Groups.Io
<femtocam=yahoo.com@groups.io> wrote:

I did some further trouble shooting. The problem must be on the A5 board,
as I can see the same issue with the vertical artifacts when I install the
board on a different 2465b.
The A5 had some leaky capacitor which I replaced. Traces were all good.
After I realized that the problem is on the A5 I replaced some of the
smaller capacitor and resistors, as they showed some corrosion.
Unfortunately this did not fix the issue.
Does anyone has an idea what else could be wrong
There are two signals that go from the readout circuitry to the display
sequencer to enable readout, and to unblank it. The two signals are /ROA
and /ROB, you may want to look at the blanking signal in particular, I
think.


Re: Tektronix 2235 beam+focus instability

Chris Smith <me@...>
 

Hi,

Unfortunately I can't answer that. It was stored for a long time I suspect. It was purchased at a hamfest for 25 GBP recently. The seller assured me that it worked but I didn't believe a word of that. Nothing I've bought at a hamfest worked! :) It was powered up for about 10 minutes initially which wasn't really enough time to pick this up, then the power supply exploded.

That's an interesting theory. I couldn't correlate it to motion; I tried tapping the chassis etc. Could be thermal expansion causing it. I will pull the tube out and reseat everything and see what happens. I only tested the tube base in situ so it's possible that there's a thermal problem on the pins on the base or something. I'll do that when I get a few minutes.

Thanks for the reply :)

Best regards,

Chris

On Sun, 10 Mar 2019, at 15:49, Roger Evans via Groups.Io wrote:
Chris,

Has the scope functioned correctly and stably since in your possession (ie before the power supply blew)? The spot is so far off centre with no voltage on the deflection plates that it could be there is some internal damage to the CRT. If something is loose internally then the motion of the spot should correlate with moving or tapping the scope.

Roger




Re: 2465B vertical lines when readout is on

Craig Cramb
 

On Sat, Mar 9, 2019 at 09:23 PM, Dr. Bernd Burfeindt wrote:


Unfortunately this did not fix the issue
Have you done the 2465B CRT adjustment procedure in the service manual?

Craig


Re: Tektronix 2235 beam+focus instability

Roger Evans
 

Chris,

Has the scope functioned correctly and stably since in your possession (ie before the power supply blew)? The spot is so far off centre with no voltage on the deflection plates that it could be there is some internal damage to the CRT. If something is loose internally then the motion of the spot should correlate with moving or tapping the scope.

Roger


Re: Tektronix 2235 beam+focus instability

 

On Sun, Mar 10, 2019 at 04:13 PM, Chris Smith wrote:


Unfortunately 100% sure this is correct.
Hi Chris,
That really is surprising! AFAIK, all electrodes left connected after disconnecting the plates are "circular symmetrical" so nothing should be able to put the spot this far off center screen. Looks like electron gun misalignment (shock/drop damage) and possibly broken/unreliable connection(s) inside CRT. OTOH, quite surprising that the 'scope functions normally otherwise.
Permanent magnetisation may explain the spot offset but I'd expect image distortion with that. And it doesn't explain the jitter. The is *no* vertical jitter, right?
Further things to check/try may be:
How does it (the CRT) react to tapping? Any microphonic effects?
You may temporarily connect horizontal and vertical plates together (two groups). Shouldn't make any difference
Is the large, mostly horizontal offset present with plates connected?
How about horizontal (and vertical) linearity and max. amplitude?

Raymond


Re: 2467B geometry

Harvey White
 

On Sun, 10 Mar 2019 01:21:01 -0800, you wrote:

Chuck and Rolynn:
re: staircases. Easy way to do that, take a binary counter and run a
10k, 20K and 40K( 39.9K?) resistor to a summing point. Instant 8
level stairstep generator. Expand as needed. If you do that with a 4
bit counter, and use the remaining input for a signal from an 8 bit
multipexer, you have a cheap scope switch.... Digital only, unless you
use analog switches.

Harvey




TEK spec

"X-Axis Low-frequency Linearity
0.1 division or less compression or expansion of
a two-division, center-screen signal when
positioned within the graticule area.

Y-Axis Low-frequency Linearity
0.1 division or less compression or expansion of
a two-division, center-screen signal when
positioned anywhere within the graticule area."

This is really compression of the amplifiers, vs screen position, not line curvature or geometry!

two have almost perfect geometry, the is other off by ~ a dim tracewidth <<1/20 div
The 2467B with CCW GEOM trim,~ 1/20 div.
All are well within the 0.1 div TEK linearity spec.

Can any TEK CRT veterans assist?

Harvey, re frame standardizers, the 067-0587-02 would work but are TEK 7000 plugins, and cant output to an external scope:

http://w140.com/tekwiki/wiki/067-0587-02

What we need is a ROM generating staircases run scope in X-Y mode.

Pity that the TEK CAL has no dot pattern for this purpose!

Cheers,

Jon








Re: 2467B geometry

Chuck Harris <cfharris@...>
 

I settled the grid issue, to my satisfaction, by hooking a
1 division square wave to the CH1, 2, and 3 inputs, turning
on the CH1-4 display, and triggering on AC mains.

I adjusted the vertical positions so that the pair of lines
visible for CH1-3 covered the lower graticule lines, and the
baseline trace covered the upper graticule line... leaving
out the top most, and the bottom most graticule lines, as
tek doesn't seem to think them relevant.

I then adjusted the time cursors to the first and last
graticule line, and the full picture of the distortion became
visible.

Lets number our horizontal graticule lines as follows:

outer most top line we ignore.
1-4 where 4 is the center line.
4-7 where 4 is again the center line.
outer most bottom line we ignore.

My CRT is almost perfect on line 1, but grows more and more
bowed to a peak at line 3, where it grows less and less
bowed to a straight line at line 5, After line 5 it starts
to bow downwards, to line 7 where it is bowed a little.

As to physical damage:

The 2467 CRT is built like a brick outhouse, except in 4 elements.

These elements are fringe shields for the vertical and horizontal
deflection plates, and are basically V shaped channels that are
positioned at the sides of each plate pair... in other words,
they cover the space between the left and right horizontal plates,
and the up and down vertical plates.

These shields are connected to anode1, and can be seen on the CRT
schematic as dashed lines.

Anyway, these are longish structure that are only fixed on one
end.

Everything else in the CRT is fused to the heavy glass rods that
define the positions and structures of the CRT.

-Chuck Harris

Harvey White wrote:

On Sat, 9 Mar 2019 21:38:36 -0500, you wrote:

Two frame calibration standardizers will work, I think, certainly one
will give you horizontal lines. I seem to remember using two of them
and getting a grid. Different scan rates, though.

Harvey


Hi Rolynn,

There is no setting of the geometry that will allow
my 2467B to have a straight horizontal trace in the
center of the screen. It either bows up a little bit,
or it bows up a lot. The switch between bowing up and
bowing down is about 2 divisions from the bottom of
the CRT.


Re: 2467B geometry

Siggi
 

On Sat, Mar 9, 2019 at 8:26 PM Jean-Paul <jonpaul@ix.netcom.com> wrote:

Geometry issue in 2467B, trimpot is fully CCW and still not perfect.

after tweaking, best results, 4 ch ON

Chuck your comments? Compared to yours?

Jon

(see new album 2467B GEOMETRY for photo)
And here's a link to the album for posterity:
https://groups.io/g/TekScopes/album?id=86473


Re: Tektronix 2235 beam+focus instability

Chris Smith <me@...>
 

Hi,

Unfortunately 100% sure this is correct. Hence why I'm completely stumped!

Have checked all rails and the entire HT side of things with DMM and HT probe. No jumps or changes. Every electrolytic in the unit has been replaced. All LV rails are in spec, checked with scope and DMM. I am running this up on a bench supply via the LV supply test points at the moment. I initially thought it might be external magnetic influence somewhere but nothing when the scope is fully assembled, running off the mains supply.

Totally have no idea what is going on. Never seen this before myself. I've even sat there in the dark like a crazy person for an hour and looked for arcing.

Best regards,

Chris

On Sun, 10 Mar 2019, at 15:05, Raymond Domp Frank wrote:
On Sun, Mar 10, 2019 at 07:13 AM, Chris Smith wrote:


I disconnected the vertical and horizontal amps from the tube and fired it up
and took this video
Are you sure this is correct?
With vertical and horizontal plates disconnected, the spot should be positioned near mid-screen.
Also, in your video, the irregular horizontal movement and brightness variation seem asynchronous, correct?
Otherwise, I'd suspect a common power supply voltage to hor. and z-axis but not vertical (if that indeed does not jitter), like + 100 V and check that for jitter. Did you check all low voltage supplies incl. 100 V? Often caps like C954 and others in a LVPS fail. I've seen high ESR, loss of capacitance and jittery leakage in them.

Raymond
Raymond




Re: 2467B geometry

Chuck Harris <cfharris@...>
 

Jon,

I have to say that it is not compression of the amplifiers.

If it were compression of the vertical amplifier, it would
be uniformly compressed across the entire horizontal dimension
of the CRT.

If it were compression of the horizontal amplifier, it would
be uniformly compressed across the entire vertical dimension
of the CRT.

It is neither.

Remember, the vertical and horizontal amplifiers are completely
isolated of each other (+/- some stray coupling). Neither knows
the other exists.

Further, it is pretty clear that Tektronix knew there was a
problem... look at your graticule, and notice that they
erased the vertical graticule lines in the outer two
divisions.

Clearly, they thought there was something wrong out there,
that wasn't as wrong in the 2465's CRT.

-Chuck Harris

Jean-Paul wrote:

Chuck and Rolynn:

TEK spec

"X-Axis Low-frequency Linearity
0.1 division or less compression or expansion of
a two-division, center-screen signal when
positioned within the graticule area.

Y-Axis Low-frequency Linearity
0.1 division or less compression or expansion of
a two-division, center-screen signal when
positioned anywhere within the graticule area."

This is really compression of the amplifiers, vs screen position, not line curvature or geometry!

two have almost perfect geometry, the is other off by ~ a dim tracewidth <<1/20 div
The 2467B with CCW GEOM trim,~ 1/20 div.
All are well within the 0.1 div TEK linearity spec.

Can any TEK CRT veterans assist?


Re: Tektronix 2235 beam+focus instability

 

On Sun, Mar 10, 2019 at 07:13 AM, Chris Smith wrote:


I disconnected the vertical and horizontal amps from the tube and fired it up
and took this video
Are you sure this is correct?
With vertical and horizontal plates disconnected, the spot should be positioned near mid-screen.
Also, in your video, the irregular horizontal movement and brightness variation seem asynchronous, correct?
Otherwise, I'd suspect a common power supply voltage to hor. and z-axis but not vertical (if that indeed does not jitter), like + 100 V and check that for jitter. Did you check all low voltage supplies incl. 100 V? Often caps like C954 and others in a LVPS fail. I've seen high ESR, loss of capacitance and jittery leakage in them.

Raymond
Raymond


Re: Tektronix 015-0580-00 Pocket Signal Generator

Colin Herbert
 

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of tekscopegroup@miwww.com
Sent: 10 March 2019 12:51
To: TekScopes@groups.io
Subject: [TekScopes] Tektronix 015-0580-00 Pocket Signal Generator

I came across this on ebay, but description was very sketchy and could not find much info online. Is this actually a generator, or just an input connector? If it is a generator, what frequency (range) does it output? What is it used for?

Thanks for any info.


Tektronix 015-0580-00 Pocket Signal Generator

tekscopegroup@...
 

I came across this on ebay, but description was very sketchy and could not find much info online. Is this actually a generator, or just an input connector? If it is a generator, what frequency (range) does it output? What is it used for?

Thanks for any info.


Re: 2467B geometry

Jean-Paul
 

Chuck and Rolynn:

TEK spec

"X-Axis Low-frequency Linearity
0.1 division or less compression or expansion of
a two-division, center-screen signal when
positioned within the graticule area.

Y-Axis Low-frequency Linearity
0.1 division or less compression or expansion of
a two-division, center-screen signal when
positioned anywhere within the graticule area."

This is really compression of the amplifiers, vs screen position, not line curvature or geometry!

two have almost perfect geometry, the is other off by ~ a dim tracewidth <<1/20 div
The 2467B with CCW GEOM trim,~ 1/20 div.
All are well within the 0.1 div TEK linearity spec.

Can any TEK CRT veterans assist?

Harvey, re frame standardizers, the 067-0587-02 would work but are TEK 7000 plugins, and cant output to an external scope:

http://w140.com/tekwiki/wiki/067-0587-02

What we need is a ROM generating staircases run scope in X-Y mode.

Pity that the TEK CAL has no dot pattern for this purpose!

Cheers,

Jon


Tektronix 2235 beam+focus instability

Chris Smith <me@...>
 

Hi all,

I've got a 2235 here which is being a pain. I'm doing a full refurb on it as the power supply exploded. This is fortunately resolved now. However there is now a problem with the HT that I can't seem to iron out. The brightness is unstable and the beam moves around slightly. I have checked the HT out and the entire thing is voltage stable when this happens. I initially suspected the usual 510K carbon comp resistors so those were replaced with 510K Vishay VR37s (turned out someone else had already done a couple and used 470k 1/4W MF?!!). No change. I suspected the multiplier was at fault next so I replaced that with a working pull but it made no difference to the outcome again. I have checked the anode lead etc for signs of arcing but nothing. Tube base is clean and nothing appears to be up there.

I disconnected the vertical and horizontal amps from the tube and fired it up and took this video which explains what is happening: https://youtu.be/Lo-WzwbXh1Q

When connected, the rest of the scope functions 100% fine but with the same beam instability.

Can anyone shed any light on this? Any help appreciated!

Best regards,

Chris


Re: 2465B vertical lines when readout is on

Dr. Bernd Burfeindt
 

I did some further trouble shooting. The problem must be on the A5 board, as I can see the same issue with the vertical artifacts when I install the board on a different 2465b.
The A5 had some leaky capacitor which I replaced. Traces were all good. After I realized that the problem is on the A5 I replaced some of the smaller capacitor and resistors, as they showed some corrosion. Unfortunately this did not fix the issue.
Does anyone has an idea what else could be wrong

Bernd


Re: 2467B geometry

Harvey White
 

On Sat, 9 Mar 2019 21:38:36 -0500, you wrote:

Two frame calibration standardizers will work, I think, certainly one
will give you horizontal lines. I seem to remember using two of them
and getting a grid. Different scan rates, though.

Harvey


Hi Rolynn,

There is no setting of the geometry that will allow
my 2467B to have a straight horizontal trace in the
center of the screen. It either bows up a little bit,
or it bows up a lot. The switch between bowing up and
bowing down is about 2 divisions from the bottom of
the CRT.

I can get the top flat, or the bottom flat, or the
right side flat, or the left side flat, but not all
at the same time.

I think it is time to think of a way of making a clean
grid of traces that simulates the graticule, and to
make a series of pictures of what the geometry control
does.

Do you know who was responsible for the MCP crt over
at tektronix? Perhaps he would know what is going on.

-Chuck Harris

ROLYNN PRECHTL K7DFW wrote:

At the top of the screen, and the bottom of the screen, the trace
is nearly perfect. As soon as you are on division down from the
top, or 1 division up from the bottom, it starts to bow. Somewhere
near the center of the screen the bow changes from up to down.
================================================================================

Two 2467's here, not B's. Both are the same, perfect and straight with V Position at the center of the graticule and a trace width bow up at the top of the graticule and a trace width bow down at the bottom of the graticule.

180 out from what you are seeing.

Rolynn



Re: 2467B geometry

ROLYNN PRECHTL K7DFW
 

Do you know who was responsible for the MCP crt over
at tektronix? Perhaps he would know what is going on
=================================================================

I do not.

Rolynn


Re: 2467B geometry

Chuck Harris <cfharris@...>
 

Hi Rolynn,

There is no setting of the geometry that will allow
my 2467B to have a straight horizontal trace in the
center of the screen. It either bows up a little bit,
or it bows up a lot. The switch between bowing up and
bowing down is about 2 divisions from the bottom of
the CRT.

I can get the top flat, or the bottom flat, or the
right side flat, or the left side flat, but not all
at the same time.

I think it is time to think of a way of making a clean
grid of traces that simulates the graticule, and to
make a series of pictures of what the geometry control
does.

Do you know who was responsible for the MCP crt over
at tektronix? Perhaps he would know what is going on.

-Chuck Harris

ROLYNN PRECHTL K7DFW wrote:


At the top of the screen, and the bottom of the screen, the trace
is nearly perfect. As soon as you are on division down from the
top, or 1 division up from the bottom, it starts to bow. Somewhere
near the center of the screen the bow changes from up to down.
================================================================================

Two 2467's here, not B's. Both are the same, perfect and straight with V Position at the center of the graticule and a trace width bow up at the top of the graticule and a trace width bow down at the bottom of the graticule.

180 out from what you are seeing.

Rolynn

28561 - 28580 of 183709