this is a common issue with older scopes, the contacts inside the volts/dev switch and/or fine adjust knob are dirty. they aren't too terribly easy to clean - you can take it apart and try spraying in some contact cleaner while turning the knobs to try to clean it up. of course have the scope unplugged and discharged ;) this also can affect the time/dev knob. May require removal and disassembly of the switches to get the cleaner at them. (no fun)
I have an old Hitachi Scope...you just need to rotate the controls a few times each day, that's what I did with mine. The switches are a liltle dirty, so just work them.
Hey, sorry I'm no expert at all on oscilloscopes, but I have a little experience. If you want to start by excluding possibilities, you could check if it is only when you physically stress the buttons that the change occurs, or whether it is enough to make an electrical contact (touch them with the skin). If the cause it the latter, there might be some faulty earth/ground connection inside. Just an idea, don't know whether it can help you.
this is a common issue with older scopes, the contacts inside the volts/dev switch and/or fine adjust knob are dirty. they aren't too terribly easy to clean - you can take it apart and try spraying in some contact cleaner while turning the knobs to try to clean it up. of course have the scope unplugged and discharged ;) this also can affect the time/dev knob. May require removal and disassembly of the switches to get the cleaner at them. (no fun)
I have an old Hitachi Scope...you just need to rotate the controls a few times each day, that's what I did with mine. The switches are a liltle dirty, so just work them.
Hey, sorry I'm no expert at all on oscilloscopes, but I have a little experience.
If you want to start by excluding possibilities, you could check if it is only when you physically stress the buttons that the change occurs, or whether it is enough to make an electrical contact (touch them with the skin). If the cause it the latter, there might be some faulty earth/ground connection inside.
Just an idea, don't know whether it can help you.