It was made in 1963, so I have replaced all electrolytic capacitors and everything works, except one clitch: when I adjust beam intensity brighter, then also signal amlitude grows at CRT.
At max intensity sinewave or square seems to be 2 times bigger, then at minimum intensity.
Very annoying.

Any suggestions, what can be problem?
Thanks
T.

 

Hello,

It looks like there are problems with the high voltage.
As the intensity is higher the high voltage gets lower and the picture is larger.

Bertus

 

If high voltage gets lower, then image should go dimmer, but why larger?

T.

 

I had the 1964 US Navy version of that same scope. When I first got it, it had the problem that when you pushed on the beam finder, the picture went away completely. The problem turned out to be two high voltage capacitors; the problem was easily determined because the caps arced!

As for your problem, it seems there is a relationship between how much current the supply is delivering and the amplitude of the vertical amplifier.

 

Best to check the regulation of all the power supply rails as you change the intensity setting.

 

You could try asking in the hp_agilent_equipment discussion group, which can be found at yahoogroups.com .

 

A lower HV at the anode will cause a picture to "bloom" as they used to call it on TVs. It may have a HV regulator tube in it like some older TVs of that era used 6BK4s.

 

You mean the horizontal deflection opens up or the vertical amplifier shows larger amplitude? If it opens up the singnal should grow vertically and horizontall, that happends if the horizontal output is getting higer V from the flyback or the HO transistor.
Seems to me you have a problem in the vertical amp. I do not know that scope does it has two separate channels?. It is probably a dual beam,check the gain of the transistor in the vertical amp. But it is strange the intensity control is related to that.