Found a Micronta VTVM

[bob91343]

Just to confuse matters, many VTVMs used other value resistors. For instance, 22 Megohm and 100 Megohm values have been used.

Lacking a manual, you need to trace the circuit and see what resistors are in the range switch. You can apply a known voltage and add resistance until the ranges switch as they should. In other words, the resistor is part of the voltage divider and needs to be the correct value in order for the ranges to work properly, one to the next.

The first thing is to see if the meter responds to a voltage at the DC input. If so, you are in business; if not, some troubleshooting is in order.

[Kevin Kuehn]

That's very interesting. I can't imagine what the purpose would be of putting that high of value isolation resistor out in the prob, unless it's a specific very high voltage probe? 1 meg does seem to be the most common.