[SOLVED] Tektronix 535A Oscilloscope with CA plugin

Thread Starter

sasaudio

Joined Oct 18, 2009
10
I have a 535A scope with CA plugin. I have both A and B channels working just fine.

The problem I am having is that when I switch to either "Alternate or chopped Mode"
only one line appears on the scope, not two, one for A and the other trace line for B Channel.

Besides that, both A and B vertical positioning knobs can move the line up and down. That should not be.
I have replaced tubes 154 and 145 and exchanged tubes around in the CA module. Did not help.

Any help would be appreciated.

cheers

pos
 

MrChips

Joined Oct 2, 2009
27,119
Here are somethings to try.

Connect a signal source to the A and B inputs. You can use the CAL OUT as a signal source.
Set both TIME BASE A and TIME BASE B TRIGGER MODE to AUTO.
 

crutschow

Joined Mar 14, 2008
30,788
Sounds like the channel switching multivibrator is not working properly.
If you don't have it, here is a download for the CA manual which should help with your troubleshooting.

Below is a clip from the manual that shows the switching multivibrator circuit:

1661404844331.png
 
Last edited:

Thread Starter

sasaudio

Joined Oct 18, 2009
10
Here are somethings to try.

Connect a signal source to the A and B inputs. You can use the CAL OUT as a signal source.
Set both TIME BASE A and TIME BASE B TRIGGER MODE to AUTO.
I did and still one line. The "add" mode works however.

Will check into multivibrator, change all the tubes.

Thanks for time and help.

pos
 

Thread Starter

sasaudio

Joined Oct 18, 2009
10
Replaced V3382 and Alternate and chopped modes are working properly.

A Huge thank you to both Mr. Chips and Mr. Crutschow. Thank you for the clear schematic as well.

pos
 
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