Ok! What does setting the multimeter to 20 DCV or 200 DCV mean?
That sets what voltage range the meter will utilize in displaying the value. Most meters today also have a auto voltage range option, but I don't know what specific meter you are using and how many digits it uses in it's display. But if you have a 1.7vdc signal being measured by a typical '3 1/2 digit' meter, if it's in the 20DC range it will display as 1.700 if it's a 3 1/2 digit meter and will display 1.7 if it's turned to the 200DCV range.
So set to 20DCV, means the meter can display from 0000 to 1.999 volts DC and if on the 200DCV range it can display 0000 to 199.9 volts DC. Any voltage higher then these in those ranges will display 'over range' in whatever manner your specific meter uses to signal the user of that situation. If your meter has a auto-range function then it will read the voltage and use the range that allows the value to be displayed using the best resolution in can to display it.