On normal working mode (real time mode?), theres no problem. When i press the store button, an insane amount of noise is displayed on the screen. On a square wave or a static signal (like 5v), im able to remove most of the noise (almost all noise left, is when the signal changes) using the pot for setting the vertical position, and the balance trim pot. Even tapping the pot seems to make a difference. At some positions the signal is present, but overloaded with noise - at other positions, theres nothing but noise.
Sometimes when im trimming the pots, it seems like the whole display is flickering, so a noise peak, that was present 50ms ago, is now gone and visa versa (a clean signal 50ms ago, suddenly have noise).
So i think it might be the signal coming from the store function to the display, that is somehow getting contaminated. Does this sound legal, or did any of you guys have a simular problem, that was caused by something else?
The scope is a gould os-1420, theres a user/service manual here: http://www.mr2.net/marknias/gould1420.pdf
Please note, theres nothing wrong with the probes or the input signals.