Resistor 150k Measuring 120k after soldering

[rokus666]

 I have put 2 resistors on the board 150k value
Before I have soldered them in they measured 150k and after soldering, both are 120k

Is this a coincidence ?
Should I replace both?



please help

[Jordan A.]

It may well be normal, you usually can't measure resistance in circuit because other resistances appearing in parallel will throw off your reading.

cheers,

jordan

[Govmnt_Lacky]

Are you measuring the resistors "IN CIRCUIT?"

You will never get an accurate resistance measurement while the resistor is in the circuit. Unless, of course, it is all by itself and not connected to other components at all.

EDIT: Sigh..... Jordan beat me by a few milliseconds 

[rokus666]

The 32 resistors are soldered to the board.

There is nothing else on it soldered.  Only those 2 that are 150k measure 120k

It's a maestro brassmaster bought from GGG

[R.G.]

You really have to pull up one end of the resistor to get an accurate reading, for reasons already mentioned.

It is possible that soldering heat changed the value. This used to be a problem with carbon comp, but is less so with modern resistors.

[LucifersTrip]

...as mentioned, the resistance you're measuring "in circuit" includes other components in parallel...which means the resistance "in circuit" can not be larger that the "out of circuit" value...only less.


http://diyaudioprojects.com/Technical/Electronics/parallel-resistor-calculator.htm