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Author Topic: Testing Resistors  (Read 1397 times)

memoryman

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Testing Resistors
« on: November 17, 2015, 09:49:43 PM »
I just tested a 68K 10% and it tested at 76.7K ohms is it too far out of spec? How do I determine this for myself?

Roly

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Re: Testing Resistors
« Reply #1 on: November 18, 2015, 12:39:19 AM »
68k + 10%

68k + 6.8k = 74.8k

So 76.7k may be out of spec if you are using an expensive and accurate ohmmeter, however it is unlikely that it is, and even if so that it would seriously effect the circuit - there are simply too few places where such a difference wouldn't be within the tolerance of the circuit (or they would have originally fitted a 5% or 1% component, and they don't).

Measure a known new one(s) of any values(s) and see if they all come up reading a bit high.  If so, relax.  If not we are talking a fraction of a cent - replace it.

Audio circuits just ain't that critical, +/-20% or more would still cut it fine.    :tu:
If you say theory and practice don't agree you haven't applied enough theory.

memoryman

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Re: Testing Resistors
« Reply #2 on: November 18, 2015, 02:39:23 PM »
Thank you Roly its always good to hear from you.

Enzo

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Re: Testing Resistors
« Reply #3 on: November 18, 2015, 03:22:40 PM »
And was the resistor already soldered into a circuit?  If so, make sure to measure, then reverse the meter leads and remeasure.  That will expose any tiny residual voltages confusing the meter.

memoryman

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Re: Testing Resistors
« Reply #4 on: November 18, 2015, 06:26:05 PM »
Good idea Enzo I will do that, thanks :)

 

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