Problem/Question with Hantek DSO5072P

[imechura]

Howdy,

My wife bought me my first scope (a Hantek DSO5072P)as a birthday present back in July. Either something is wrong with the way it functions or I am just misunderstanding how to use it.

Is it normal that when I'm measuring a signal with the measure panel, that the displayed voltage measurements (maximum, minimum, etc) changes when I turn the VOLTS/DIV knob? It does not make any sense to me that it behaves this way because it makes every VOLT/DIV setting except one display an inaccurate value. Sometimes it will say that my 4 Volt DC signal is over 40 volts and it will also read a higher voltage as lower if the knob is adjusted downward.

I attempted to get help from Hantek but the literature does not cover this topic and the only online help I could find was in Chinese.

This has become so frustrating that I spent the weekend repairing an old analog tektronix boat anchor that I got ripped off on by an ebay seller. Needless to say I've had bad luck when it comes to scopes.

Thanks ahead of time for any insight.
Ian

[jjoonathan]

DSOs are NOT good at measuring precise voltage levels. A >>$10k DSO will struggle to measure voltage to the same precision as a $10 multimeter. It can be forgiven since it makes ~billions of measurements per second.

Below the $10k pricepoint, DSOs almost all have 8 bits = 256 vertical levels. These will be spaced evenly from the bottom to the top of the screen. If the waveform is small, the waveform will only cross a few levels, and the precision will be terrible. If the waveform is scaled to nearly fill the screen, the voltage precision will merely be bad.

In other words, what you see is normal. Hantek does not have a good reputation, so it might be slightly worse than normal, but it's not a sign that the scope is broken or useless.

EDIT: s/oscilloscope/DSO/g to not confuse with CRO.