0

I'd like to change this resistor from a main board but I'm not sure about its value.

It's marked as 0.2R in the datasheet (so 0.2 Ω) but following the color code it should be 22.88 Ω.

Am I right or I'm missing something? Also, how can I know the right power rating?

enter image description here

anemiCCinema
  • 21
  • 2
  • 0.2R means 0.2 ohms. Could be a current sense resistor – Elementronics Jul 04 '22 at 21:53
  • 1
    The color codes say it's not 22.88 ohms. – Justme Jul 04 '22 at 21:58
  • 3
    Does this answer your question? [Identifying a resistor with a weird band combination](https://electronics.stackexchange.com/questions/406505/identifying-a-resistor-with-a-weird-band-combination). Based on that, 0.22R 5% 20ppm/k – Tom Carpenter Jul 04 '22 at 22:03
  • yes very useful. thanks – anemiCCinema Jul 05 '22 at 11:47
  • @Elementronics According to wikipedia: resistances less than 10 Ω have 'R' to indicate the position of the decimal point (radix point). For example: 0R22 = 0.22 Ω. So why it's marked as 0.2R in the datasheet? – anemiCCinema Jul 05 '22 at 11:57
  • @anemiCCinema They usually do, but they didn't in this case for whatever reason. I don't think anyone but the datasheet writer could tell you why. – Hearth Jul 05 '22 at 14:20

1 Answers1

3

The colour bands red-red-silver indicate it's a 0.22 ohm resistor.

Gold band means 5% tolerance.

The green means it's somehow special.

It may indicate a certain temperature coefficient.

It may indicate it's a fusible resistor which is designed to fail open under overload conditions.

It may indicate it's a non-inductive resistor if it is important to the application.

It may indicate a certain level of failure rate requirement.

If the resistor is OK, there is no need to change it.

Justme
  • 127,425
  • 3
  • 97
  • 261
  • So if i understand well the gold band is the clue to know that it's not a 5 band resistor but a 4 band resistor with an unknown band color, maybe a temperature coefficient? Also it seems to me that the surface of the resistor is slightly damaged. for now it works but I would like to change it to prevent it from burning and damaging other components of the board. I have another board like this where many SMD components got damaged afterwards that it blown. – anemiCCinema Jul 05 '22 at 11:54
  • Are you sure it's not the other way around, that other components being damaged caused the resistor to pass too much current so it overheated and got damaged? – Justme Jul 05 '22 at 12:12