Why resistance value changes while alternating positive and negative probe?

Thread Starter

Romie77

Joined Jan 4, 2020
23
While repairing a circuit (contains semiconductor), I amazed that value of resistance (shown by multimeter) is changes while positive and negative probe position interchanged with each other.
  1. Why this happen?
  2. Can it be useful to repair any circuit?
 

j0999

Joined Mar 4, 2019
18
the circuit may contain diodes(resistance changes with polarity) or thermistors(resistance changes with temperature).
Not much can be said without knowing about the circuit in detail.
 

Alec_t

Joined Sep 17, 2013
11,302
  1. Why this happen?
  2. Can it be useful to repair any circuit?
If any semiconductor junction is in the path between the two probes it will introduce asymmetry in the resistance measurement.
It may help in testing diodes and transistors, or at least detecting their presence in a circuit.
 

Thread Starter

Romie77

Joined Jan 4, 2020
23
I had attach a basic circuit.

Good circuit:
While measuring resistance between pin 1(positive probe) and ground(negative probe) is 465k ohm.
With reversing probe, resistance is 490k ohm.

Faulty circuit:
While measuring resistance between pin 1(positive probe) and ground(negative probe) is 466k ohm.
With reversing probe, resistance is more than 500M ohm (open). I had changed this IC but still it shows 500M ohm at one condition.



1580214925260-1409754576.jpg
 
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