UNI-T UT90A Operating Manual page 15

Measurement Operation(2)
l The LCD displays "1" indicating the existing selected
range is overloaded, it is required to select a higher
range in order to obtain a correct reading.
l In each range, the Meter has an input impedance
of approx. 10M . This loading effect can cause
measurement errors in high impedance circuits. If
the circuit impedance is less than or equal to 10k ,
the error is negligible (0.1% or less).
l When DC voltage measurement has been completed,
disconnect the connection between the testing leads
and the circuit under test.
Model UT90A: OPERATING MANUAL
15