Resistor value changes when measured

[kapsel]

Hi guys,

Ok , this question is a bit weird. I got a second hand Marhsall Drivemaster and opened it to clean it (contacts etc) as it was rather dirty.
I measured each resistor value with a multimeter and noted  it down for future reference.
While for all resistors as soon as i touch the probes at the leads, the multimeter screen shows the value immediately, when i try to measure a particular one (47 k) it starts at c. 20k and gradually increases reaching 47k after 15-20 seconds or so.
Is this normal? Should I replace it with a new one?
[Or am I just a freak?  ]

Cheers

[pakrat]

I don't think you can accurately measure resistors in circuit, you need to lift one leg.

[kapsel]

That seems so obvious yet it didn't cross my mind.
Thanks, I'll stick to colour codes for this one then.

[Jdansti]

I don't think you can accurately measure resistors in circuit, you need to lift one leg.

+1
You might have caps connected to the resistors, which could cause an up/down movement of your readings.  You might also have other resistors attached to any given resistor in parallel and/or series.

[duck_arse]

try measuring that one resistor one way, then reverse the meter leads and measure again. what happens?

[Digital Larry]

Switch over to voltage measurement real quick.  If you read something which gradually (or quickly) goes towards zero, then you were charging capacitors.