Cant identify Resistor color code

Discussion in 'General Electronics Chat' started by Nelson2001, Sep 17, 2015.

  1. Nelson2001

    Thread Starter Member

    Nov 10, 2011
    27
    0
    I reparing a power supply (thermaltake PFC control), high end psu. In the mobo i found this set of resistor but can`t identify colors.
    , so her values. They are in the primary side of the PSU.
    I google it, i think they are fuses, or inductances but not!.
    You cAn help me?. Thank you in advance! P1060958.JPG
     
  2. Dodgydave

    Distinguished Member

    Jun 22, 2012
    4,976
    744
    I would say the top and bottom ones are inductors as they have spiral wire wrapped around the body, the middle one maybe 0.1 ohms, but if they all read 0.4 ohms then they're all inductors. You need an inductance meter or dvm with built-in range,

    Best guess top to bottom...

    8.2uH
    11.8mH
    7.5mH
     
    Last edited: Sep 17, 2015
    Nelson2001 likes this.
  3. ian field

    Distinguished Member

    Oct 27, 2012
    4,413
    782
    They look a lot like wire wound power resistors to me.

    Normally anything with a gold multiplier band would be less than 10R, and anything with a silver multiplier would be less than 1R - but I wouldn't discount the possibility of close tolerance resistors with an extra colour band. An extra band is an extra digit so the value would be 10x more than a quick glance at the multiplier band suggests.

    Some DMMs are not capable of resolving anything under 1R, so the values quoted aren't too surprising.

    The favourite method of measuring very low resistances is to build a constant current source and calibrate it - if you know the exact current you pass through a resistor; the volt drop will allow you to calculate the resistance.
     
    Nelson2001 likes this.
  4. wayneh

    Expert

    Sep 9, 2010
    12,100
    3,034
    Ditto. My money is on low ohms resistors, maybe used as current shunts in the PCB.

    On the other hand, that one in the middle with a silver band in the middle is perplexing. I'm not aware of any resistor code that would put a silver band in the #3 band position.

    And now that I think about it, black isn't a valid color for the 5th band (top part), either. Maybe I'm talking myself away from resistors.
     
    Last edited: Sep 17, 2015
    Nelson2001 likes this.
  5. ian field

    Distinguished Member

    Oct 27, 2012
    4,413
    782
    The band(s) at the other end probably do more than just the tolerance.

    There doesn't seem to be any set in stone standard, an extra band there can indicate magnitude of temperature coefficient, or just that its "high stability".
     
    Nelson2001 likes this.
  6. be80be

    Senior Member

    Jul 5, 2008
    431
    57
    Buy a banggood transtor tester it really a parts tester but it can test inductors and capacitors resistors diodes and of course transistors
     
  7. Nelson2001

    Thread Starter Member

    Nov 10, 2011
    27
    0
    Thank You all, I take a few more pictures, from the mobo and I see clearly R printed in it.
    Don't know how it works. May be jus like fuses?
     
    Last edited: Sep 17, 2015
  8. GopherT

    AAC Fanatic!

    Nov 23, 2012
    6,006
    3,763
    They are low ohm resistors. If your. Ever has a RELATIVE function, short the test leads together to measure resistance of the leads and connections. Then press relative to zero and measure the resistance. They are likely current sensing resistors, low and very low ohms.
     
    Nelson2001 likes this.
Loading...