I recently picked up a faulty Hitachi V-1150 'scope and after fixing a problem in the power supply it now starts up. However, it only uses the very middle of the screen vertically, and goes wild if I try to lower the volts/div.
My theory that the oscilloscope "thinks" that the screen is smaller than it is is also backed by the fact that turning the vertical position knobs to their extremes only moves the trace up and down a tiny amount.
As you can see from the pictures, the entire trace is also shifted to the right.
The largest I can get the trace so the waveform is displayed accurately:
When I decrease the volts/div:
Does anyone have any ideas about the cause(s) of these problems?