Blanking the retrace - Analog scope

atferrari

Well-Known Member

Most Helpful Member

• Jul 19, 2009

• #1

I managed to show on my scope a symbol formed by several dots by controlling voltages at the X-Y axis.

To make it neat I would need to blank the retrace between dots.

My scope is an old analog TRIO 10 MHz CS1562A. Couldn't find the manual but a PDF version found in the Web says that "modulation" may be done "at TTL" levels.

Just in case, I tried myself bringing the Z axis input to 0V and 5V, getting only a change in brightness.

Is it any way I could blank completely the retrace in between spots?

 

Last edited: Jul 19, 2009

Nigel Goodwin

Super Moderator

Most Helpful Member

• Jul 19, 2009

• #2

I suggest you consult the circuit, and see if applying more voltage will blank it further - but it may be as far as it's supposed to change. Z inputs I've looked at in the past require LARGE voltage changes, as the essentially drive the cathode (or grid) pretty well directly.

 

atferrari

Well-Known Member

Most Helpful Member

• Jul 19, 2009

• #3

Thanks Nigel

You were online, I can see. Thanks for replying,Nigel.

I am affraid of trying any different from the manual because of that of "TTL levels". It is the only scope I have and no money to replace it in the near future...

Would you say that it could be safe to try any different?

 

Nigel Goodwin

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• Jul 19, 2009

• #4

Like I said, consult the scopes circuit - if you have it?.

 

atferrari

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Most Helpful Member

• Jul 19, 2009

• #5

Z axis input

There are several transistors between the Z input and the grid in question.
I presume, it precludes applying any high voltage to it.

 

Nigel Goodwin

Super Moderator

Most Helpful Member

• Jul 19, 2009

• #6

atferrari said:

There are several transistors between the Z input and the grid in question.
I presume, it precludes applying any high voltage to it.

Click to expand...

I would imagine so, can you post a scan of that part of the circuit?.

 

crutschow

Well-Known Member

Most Helpful Member

• Jul 19, 2009

• #7

Try reducing the trace intensity. You may find a point where the beam is blanked but still retains sufficient intensity to see the dots.

 

atferrari

Well-Known Member

Most Helpful Member

• Jul 19, 2009

• #8

Problem solved

Problem solved: applying -5V to the input did the trick.

Gracias to you both for replying.