I found this this component at the power supply input of a circuit. I tested it with the multimeter. It measures an open circuit. I couldn't figure out its value or its type.

It is located before a bridge rectifier and a varistor. It has no label on the board.

The colors are: white, gold, black, white and orange.

enter image description here

  • 1
    \$\begingroup\$ The smartass in me wants to point out that the answer to that question is probably "Yes", unless you've found a magical resistor with zero inductance. \$\endgroup\$ Jul 2, 2022 at 1:00

1 Answer 1


It looks and sounds like a fusible resistor. I say this for two reasons (1), it measures an open circuit (it has fused hence the reason you are investigating it) and (2), fusible resistors quite often have their 5th band coloured white. See this website about the 5th band: -

enter image description here

It is located before a bridge rectifier and a varistor.

Given where you describe it to be in the circuit; that place is usually where SMPS devices have a fuse and, many of them use fusible resistors because the resistance doubles up to reduce inrush current.

Anyway, my best guess is that it is a 3.9 Ω fusible resistor.

  • 2
    \$\begingroup\$ Why is it 3.9, as opposed to 39? I’m reading orange-white-black as 39. \$\endgroup\$
    – techrah
    Jul 1, 2022 at 20:22
  • \$\begingroup\$ Black as a third colour means no zeros after 39 but then gold means divide by ten but, it could be as you say if gold isn't included. Alternatively it could mean 390 divided by ten = 39 \$\endgroup\$
    – Andy aka
    Jul 1, 2022 at 20:57

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.