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Reduced resistance of resistor

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bob91343:
Don't rule out mismarking.  I have a bag of resistors all marked wrong.  There must be several hundred of them, marked 220 Ohms, all very different resistances.  It's either a mistake or someone threw a monkey wrench into the manufacturing process.

If I thought it was mismarking, I could measure them and relabel.  But there is the possibility that they are unstable.  It's unimportant by itself, since these parts are so cheap.  But it makes suspect many similar parts.

leftek:
The resistor write "UTM 214-8 R56 10% z" and is a Emitter resistor from power BJT.  I is from one damaged board that drive a DC motor 3A.
As i have research it is 56ohm from manufacture "Vitrohm". I am wrong?
I send it in attached file.

Twoflower:
Everything is fine with that resistor. The letter 'R' shows the decimal point of the value:
R56 = 0.56 Ohm
5R6 = 5.6 Ohm
56R = 56 Ohm

So the value show on your meter is OK as with such low resistance values you have to take the resistance of the cables and such things into account. For example connect the cables together and you'll most likely see a value > 0.

leftek:

--- Quote from: Twoflower on April 12, 2020, 09:34:08 am ---Everything is fine with that resistor. The letter 'R' shows the decimal point of the value:
R56 = 0.56 Ohm
5R6 = 5.6 Ohm
56R = 56 Ohm

So the value show on your meter is OK as with such low resistance values you have to take the resistance of the cables and such things into account. For example connect the cables together and you'll most likely see a value > 0.

--- End quote ---

Thank you very much. I did not know.

engrguy42:

--- Quote from: Twoflower on April 12, 2020, 09:34:08 am ---Everything is fine with that resistor. The letter 'R' shows the decimal point of the value:
R56 = 0.56 Ohm
5R6 = 5.6 Ohm
56R = 56 Ohm

So the value show on your meter is OK as with such low resistance values you have to take the resistance of the cables and such things into account. For example connect the cables together and you'll most likely see a value > 0.

--- End quote ---

Well there's your problem  :D

And I'm guessing the accuracy of the meter down in those low ranges (reading of 0.7 as opposed to say 0.700) is relatively low (like maybe 1% +/-  5 digits or something?). Which also might explain the difference between 0.56 and 0.7 ? I always forget how the digits thing works  :D

EDIT: I just checked the specs of the Hioki DT4252 and it says for resistance measurements: "Basic accuracy: ±0.7 % rdg. ±5 dgt."

Doesn't +/- 5 digits with a reading of 0.7 mean the actual can be from 1.2 to 0.2 ?

Also it looks like it's marked as a 10% accuracy resistor which means, hell, it can be almost anything  :D

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