HP 1740A Gain vs Position Problem

[BarryR]

The vertical gain of both channels varies with position. For instance, at .2v/div with a 10x probe, the calibrator reads 2.5 divisions with the image centered on the screen, and 3 div when set to the upper or lower part of the screen. Any ideas where I should start looking? I do not have another scope to troubleshoot this with.

 

[Ylli]

Same issue on both channels? I'd start by looking at the power supply. Make sure all the voltages are right and that they do not vary with vertical position adjustments.

 

[BarryR]

Sounds right. Thanks.