XY mode Lissajous figures are off to one side on Tektronix 475 scope ?

[2ndhandscope]

Hello,
Upon testing my new 475 Tek scope, I noticed that XY mode figures are displayed off to the right side instead of the center. When adjusting X signal vertical position, I was able to move the figure back to the center but that would mean the X signal is off center when viewed in normal modes. I have both vertical and horizontal set on the same scale, same coupling, each signal when viewed individually in normal sweep are centered vertically.
I dont have any ideas why this might be the case. Can you share your suggestions ?
Thanks!

 

[BradtheRad]

I have a Tektronix RM504. I find XY mode always needs some adjusting to obtain a satisfactory trace.

The horizontal sensitivity is much less than the vertical sensitivity. Sometimes I cannot get sufficient swing on the horizontal axis. So I have to switch which signal is X and which is Y.

The horizontal sensitivity is also uncalibrated. To get an idea how many volts per grid I was looking at, I had to draw a picture of the position knob, then mark volt figures at different spots.

 

[2ndhandscope]

You mean this is calibration issue ? Oh mind, I hate to open up the scope

 

[BradtheRad]

It's up to you whether it's worth it. You'll need to locate the horizontal input amplifier, and change whatever DC volt level it delivers to put the beam at a neutral position.

The horizontal position knob affects both sweep mode and signal-input mode. I believe the horizontal sweep circuit is separate from the horizontal input amplifier. It should be possible to track backwards from the position knob, on the chance there is an adjustment for the horizontal input amplifier.