Tektronix 465B scope trace problem

[eee100]

Hello all,

I have a Tektronix 465B analog oscilloscope. It was working without any problems but suddenly a problem with the trace has started. Now the trace doesn't appear on the whole screen. As you can see from the attached picture, the trace only appears on the left portion of the screen. This is true for both channels. "Position" knob adjusts the trace partially. So when I rotate the knob fully clockwise the trace disappears at the left and when I do the opposite the trace's maximum position is as seen in the picture. What can be the problem? What should I check? I have the service manual but I need a hint to find a start point. Any help is much appreciated.
Thank you

 

[Chris56000]

Hi!

You have a fault in the X-deflection amplifier that is putting a standing voltage on the X plates of the CRT!!! If you can post the manual or the Timebase, X Amplifier and CRT/Power Supply circuit diagrams I can give you a more detailed analysis of the fault!!!

Chris Williams

PS! I've just found a copy & I'll give you an analysis in due course!!!

 

[eee100]

Hi Chris,

Thank you very much for your reply. Wow you are going to save my life I am looking forward to your solution, thank you

 

[E-design]

Before diving into faultfinding circuitry, follow step 1 you will find in any service manual: Check all the supply voltages are present - within spec. This step is often skipped even by experienced people!