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I have a resistor that I need to replace that looks like this (4-color band resistor that is significantly bigger than the others):

enter image description here

If I read the colours correctly (brown / black / gold / gold) this should be a 1 Ω resistor, but it is considerably bigger than the normal resistors.

enter image description here

  • Is this due to it being a higher wattage?
  • Can one somehow derive the wattage by looking at the size of this resistor?
  • Does the fact that it is grey also mean anything?
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    \$\begingroup\$ Yes, it's a power resistor (high Wattage rating), and if you had more experience with such things than I have, you probably would recognize the rating by the physical size. (Probably at least 1 Watt, probably not more than 5 is my guess.) Don't know about the body color. \$\endgroup\$
    – Solomon Slow
    Aug 26, 2020 at 14:25
  • \$\begingroup\$ Power resistors are generally designed to operate at elevated temperatures. I'd guess that coating differs from other resistors due to its ability to cope with higher operating temperatures. Cost would be a reason why it is not used universally. \$\endgroup\$
    – glen_geek
    Aug 26, 2020 at 15:08
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    \$\begingroup\$ What makes you think it is bad? Unless it measures as an open circuit, chances are whatever problem you are trying to fix is elsewhere. You're going to have trouble measuring the value of a 1-ohm resistor unless you put a calibrated current through it and measure the voltage, a simple ohm-meter probably won't do it, at least not with ordinary leads held in place with finger or spring pressure alone. \$\endgroup\$
    – Chris Stratton
    Aug 26, 2020 at 18:45
  • \$\begingroup\$ trying to fix an audio power amp? doubt very much that this resistor is the problem. \$\endgroup\$
    – danmcb
    Aug 2, 2022 at 7:49
  • \$\begingroup\$ Would you measure the body length and diameter? Have you any way to estimate the equipment's age? (Such as manufacturer's plate or date codes on chips.) \$\endgroup\$
    – jonathanjo
    Sep 30, 2022 at 7:32

3 Answers 3

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To echo other users, yes it's a 1 ohm resistor to 5% tolerance. The base colour means nothing, though an experienced eye might be able to narrow down the manufacturer.

Wattage will depend on age and technology. As time went by they got smaller and ran hotter. I'd disagree with another answer as it may well be too old for that size to be 5 W rated; my guess would be somewhere between 0.5 W and 2 W, but it is just a guess.

But it probably doesn't matter; if you replace it with a modern one of similar size, the wattage should be at least as high.

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Yes. Just a 2 watt power resistor. They are widely available.The grey colour does not mean anything special.

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That is a power resistor and yes, it is bigger because it has a higher power rating.

Size versus power rating depends on age, technology and manufacturer's decisions. I have a few metal-film ones lying around from Panasonic that look similar, and they are 12 mm long for 2 W, 15 mm for 3 W, and 24 mm for 5 W. YMMV.

The colour doesn't indicate anything.

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