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Interfacing 576 Curve Tracer to 7633 Storage Scope


RellikJM
 

Hello all!

I'd like to interface my 576 Curve Tracer to my 7633 Storage scope. It would be nice to have the features of the 577D1 Curve Tracer available to the 576. I have the 176 High Power Fixture for it and it doesn't trace anything but DC points. I'd also like to do push pull matching and true 0 bias point measurement.

Is the best way to grab the deflection signal right from the CRT pins and only use 1/2 of the differential signal that the deflection plates need or do the differential signals need to be integrated some how? I was thinking that if I used the (+) side of the horizontal and vertical deflection plate signals I'd be able to feed that into the storage scope in X-Y mode. My concerns are I don't want to do any damage to the 576 and I'm thinking it would be smart to use some sort of coupling capacitor from the deflection plate signal so I'm not coupling to the +225VDC that powers the deflection plate transistors. If I couple to the deflection plates should I leave the 576 CRT in circuit with the intensity turned down while feeding an external storage scope or should the CRT be disconnected and suitable load resistors connected to substitute for the disconnected 576 CRT?

Thanks in advance,

Jay


 

Hi Jay,
Several years ago my 577 HV transformer failed and I found myself without a curve tracer for the first time in several years. It was not going to be easy to find a replacement HV Transformer. But Walter Shawlee came up with a temporary solution for me by thinking outside the box. Why not pick off the X and Y signals before they get to the deflection plates and feed them into one of your other scopes.
It was easy to find the right spot in the vertical amplifier circuit and in the horizontal amplifier circuit to connect to and bring them out to a DB-25 connector since, for some reason, my particular 577 had an optional factory installed DB-25 cutout with a cover plate since it was not actually used for anything. I never noticed this before that moment and I can't say I have ever seen it on any other 577. But it was perfect for my needs. I was using the differential signals for both X and Y so I added a DB-25 connector, wired the deflection signals to 4 pins, made an extension cable to plug into the dB-25 connector and plugged the differential signals into a pair of 7A13 or 7A22 Differential amplifier plugins (I don't remember which I used) (one was in a vertical slot and one was in a horizontal slot) of one of my 7000 scopes. It worked perfectly. So your idea is a sound one.

There are easier (and cheaper) ways to do this but since I happened to have the amplifier plugins I needed that is what I used. There are hundreds of simple double-ended (differential) to single-ended OpAmp circuits you could use that will work fine and cost just a few dollars. They would also have the advantage of working with almost any kind of scope so you don't need specialized plugins or even an expensive scope.
Google "Images for differential to single ended amplifier circuits" and you will find hundreds of examples.

Dennis Tillman W7pF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of rellikjm via groups.io
Sent: Saturday, December 19, 2020 12:18 PM
To: TekScopes@groups.io
Subject: [TekScopes] Interfacing 576 Curve Tracer to 7633 Storage Scope

Hello all!

I'd like to interface my 576 Curve Tracer to my 7633 Storage scope. It would be nice to have the features of the 577D1 Curve Tracer available to the 576. I have the 176 High Power Fixture for it and it doesn't trace anything but DC points. I'd also like to do push pull matching and true 0 bias point measurement.

Is the best way to grab the deflection signal right from the CRT pins and only use 1/2 of the differential signal that the deflection plates need or do the differential signals need to be integrated some how? I was thinking that if I used the (+) side of the horizontal and vertical deflection plate signals I'd be able to feed that into the storage scope in X-Y mode. My concerns are I don't want to do any damage to the 576 and I'm thinking it would be smart to use some sort of coupling capacitor from the deflection plate signal so I'm not coupling to the +225VDC that powers the deflection plate transistors. If I couple to the deflection plates should I leave the 576 CRT in circuit with the intensity turned down while feeding an external storage scope or should the CRT be disconnected and suitable load resistors connected to substitute for the disconnected 576 CRT?

Thanks in advance,

Jay







--
Dennis Tillman W7pF
TekScopes Moderator


Jean-Paul
 

Dear Dennis WOW! great idea, never thought of that.

Instead of a CRT storage scope I would use a modern digital scope. A 4 channel scope could he used in A-B for differential input. One could take a screen shot and export to a computer via USB, HPIB etc.

Can you please detail or post a markup of the 576 amplifiers showing the pickoff points you wired for the connection?

Many thanks


Jon


Jean-Paul
 

ReBonjour a Dennis et tous:

I just realized the solution: The 576 (not 577) SCH output amps, shows pickoff points at board connectors to gain cal pots and defl plates.

Would Add series R eg 47 k for safety, and bring V and H diff sigs to a 4 pin ext connector added to the back panel,

Instead of external diff amps, use my Yokogawa DL1740
https://doc.xdevs.com/doc/Yokogawa/YOKOGAWA%20DL1740%20USER.pdf

Set math 1 CH 1-CH 2 for diff Y
Set math 2 CH 3-CH 4 for diff X
Display math 1/math 2 as XY



defl diff Signal 576>>DL via 10x probes

VOILA! The Yokogawa is easily set to scale the signals and the display is digital on LCD, it has output to VGA and GPIB, RJ45 for Ethernet.

Utility from Yokogawa has full control, display on PC, storage of screenshots etc.


The same could be done with any digital scope that has the capability for CH 1 - CH2 and XY display of the diff signals.

Only issue is what connector to add and how to mod the 576 without damage!


Jon Paul


 

On Mon, Dec 21, 2020 at 09:55 AM, Dennis Tillman W7pF wrote:


It was easy to find the right spot in the vertical amplifier circuit and in
the horizontal amplifier circuit to connect to and bring them out to a DB-25
connector since, for some reason, my particular 577 had an optional factory
installed DB-25 cutout with a cover plate since it was not actually used for
anything. I never noticed this before that moment and I can't say I have ever
seen it on any other 577.
I have a D40 display unit (5440 'scope) with a horizontal DB-25 cutout in the cast aluminum rear chassis (not the cover plate) below the CRT socket cover.

As is well known, the 577 uses 5xxx display units so the cutout may have been standard (from a certain date).

Raymond


Tim Phillips
 

Yes, the DB-25 cut-out on the 54xx display is for Option 03,
user-programmable readout fields.
Tim

On Mon, 21 Dec 2020 at 14:36, Raymond Domp Frank <hewpatek@gmail.com> wrote:

On Mon, Dec 21, 2020 at 09:55 AM, Dennis Tillman W7pF wrote:


It was easy to find the right spot in the vertical amplifier circuit and
in
the horizontal amplifier circuit to connect to and bring them out to a
DB-25
connector since, for some reason, my particular 577 had an optional
factory
installed DB-25 cutout with a cover plate since it was not actually used
for
anything. I never noticed this before that moment and I can't say I have
ever
seen it on any other 577.
I have a D40 display unit (5440 'scope) with a horizontal DB-25 cutout in
the cast aluminum rear chassis (not the cover plate) below the CRT socket
cover.

As is well known, the 577 uses 5xxx display units so the cutout may have
been standard (from a certain date).

Raymond






 

On Mon, Dec 21, 2020 at 03:47 PM, Tim Phillips wrote:


Yes, the DB-25 cut-out on the 54xx display is for Option 03,
user-programmable readout fields.
I have a 5443 with that cutout and Option 3 in the *base unit*. I'd say it makes more sense there as well. It's a vertical cutout next to the mains transformer (to the right, looking from the back).

Raymond


 

Hi Raymond,
I'm sure you are right that all D40 display units had the DB-25 cutout on them.
I wonder what it was used for?
Dennis Tillman W7pF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of Raymond Domp Frank
Sent: Monday, December 21, 2020 6:36 AM
To: TekScopes@groups.io
Subject: Re: [TekScopes] Interfacing 576 Curve Tracer to 7633 Storage Scope

On Mon, Dec 21, 2020 at 09:55 AM, Dennis Tillman W7pF wrote:


It was easy to find the right spot in the vertical amplifier circuit
and in the horizontal amplifier circuit to connect to and bring them
out to a DB-25 connector since, for some reason, my particular 577 had
an optional factory installed DB-25 cutout with a cover plate since it
was not actually used for anything. I never noticed this before that
moment and I can't say I have ever seen it on any other 577.
I have a D40 display unit (5440 'scope) with a horizontal DB-25 cutout in the cast aluminum rear chassis (not the cover plate) below the CRT socket cover.

As is well known, the 577 uses 5xxx display units so the cutout may have been standard (from a certain date).

Raymond







--
Dennis Tillman W7pF
TekScopes Moderator