Background
I already have a (2nd hand) Philips PM 3253 oscilloscope. Although it has many features and is fast (50 MHz) the display is so bad, it's barely usable.
Therefore I bought another (2nd hand) oscilloscope, a Philips PM 3110 (2 channel, 10 MHz) with far less features). The display is much better.
Question
However, when I for example show a square wave on the oscilloscope, it is scrolling very fast, I have about 2 waves per square (cm). I tried moving the X position knob, but that only makes the left or right side being clipped/invisible.
And changing the X Magn. knob changes the scrolling, but in no way I can keep it more or less steady. I tried moving along the entire X Magn range and tried different Time Div. knob values.
What am I doing wrong? I see sometimes pictures of e.g. sinus or square waves which are not moving … or is that because a (very fast) picture is made?
Best Answer
There are several possible problems here:
You haven't set the trigger properly. Make sure that the trigger mode selector is set to "HF", the source selector is set to an input that is active, and the trigger level is set appropriately.
You may be expecting this to be a storage oscilloscope. It is not. It can only display a periodic signal which is currently being supplied to the instrument.
The oscilloscope is broken. If so, throw it away -- this was an inexpensive instrument when it was made in the 1970s, and is unlikely to be worth repairing.