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Identifying a resistor

Discussion in 'General Electronics Discussion' started by ecurbliam, Jul 24, 2015.

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  1. ecurbliam

    ecurbliam

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    Jul 24, 2015
    Hi People,
    Trying to identify a resistor that I need to replace from a Murrelectronik switch mode power supply MPS10 415V TO 24V DC power supply.
    Have used the usual resistor code identification charts but am unsure which end to start from !
    I believe it is a carbon film resistor and I have tried measuring different ones out of circuit from 3 failed power supplies of the same design .I get a reading on fluke of either 0.7 ohms or a couple of infinity.
    It is a 5 band resistor with bands as follows
    Light Blue, Silver or White, Silver or White ,Brown and lastly Green which is double the thickness of the other bands.
    I googled the green band and someone said that was the tolerance.
    So if I assume that then the value I get is 699 x 10 (6.9K) 5% Tolerance
    OR If I read from the other way 519 x 0.01 (5.19) 0.25% Precision tolerance resistor.
    I will upload a photo later as a follow up

    Please help ;)
     
  2. shrtrnd

    shrtrnd

    3,701
    462
    Jan 15, 2010
    I'm sure you'll get a reply on the color bands quickly.
    My question has to do with the condition of the resistor you'e reading. Has it been exposed to excessive heat?
    Many times I've had the color bands CHANGE COLOR when the paint heats-up from a heat over-stressed resistor.
    Are you pretty sure the paint bands are the correct color, or has the resistor been exposed to excessive heat?
     
  3. ecurbliam

    ecurbliam

    5
    0
    Jul 24, 2015
    Thanks for your reply.The resistor has possibly been exposed to heat as it is in line with the mains it does not look like the paint has heated up .Also I have looked at 3 failed power supplies and all the colour codes look the same.Here's a photo ;)
    2015-07-24 08.29.56.jpg I enclose a picture of one of them
     
    Last edited by a moderator: Jul 25, 2015
  4. shrtrnd

    shrtrnd

    3,701
    462
    Jan 15, 2010
    Actually, the paint bands look to be in good shape, so I believe they're ok.
    That component package is a 1960's era type that was pretty popular.
    It was used for some resistors, inductors, and even some capacitors.
    I'm pressed for time right now, it's Friday; but I'm thinking with two silver bands, you're pobably looking at something other than a resistor.
    If you have time (that I don't have right now), check the color code for inductors and 1960's era caps, to see if you can see a color code that makes sense.
    My money without actually looking it up, is that your component is an inductor.
    Sorry I don't have time to do the leg work myself right now.
    Good luck with the search.
     
  5. ecurbliam

    ecurbliam

    5
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    Jul 24, 2015
    Thanks again.
    The "Components" are marked up as R's on the circuit board , so wouldn't this mean they are resistors?
    Also they may be popular in the 60's but these have been made in the the late nineties onwards !
    Cheers
     
  6. Martaine2005

    Martaine2005

    2,575
    695
    May 12, 2015
    Hi
    It does appear to be a resistor. And probably an Ohmite or Allen style carbon comp resistor.
    And also probably reads Green first.
    There are some similar the 'Bay' check the picture.
    But I cannot get any resistor calculator to co-operate o_O. Resistor.JPG

    Martin
     
    Arouse1973 likes this.
  7. HellasTechn

    HellasTechn

    1,490
    210
    Apr 14, 2013
    I think the whole thing with resistor colour code is a little silly. Why not just write the value as they do on electrolytic caps or with ceramic caps ?
     
    Martaine2005 likes this.
  8. Martaine2005

    Martaine2005

    2,575
    695
    May 12, 2015
    Probably because most resistors are quite tiny, and reading values would be more difficult than coloured bands.
    Then they would have to print silly codes like on smd. That would be even more confusing...

    Martin
     
    davenn likes this.
  9. BobK

    BobK

    7,673
    1,684
    Jan 5, 2010
    Martaine2005 likes this.
  10. Martaine2005

    Martaine2005

    2,575
    695
    May 12, 2015
    Thanks Bob,
    I just bookmarked that page!!
    Now my official best calculator.

    Martin
     
  11. ecurbliam

    ecurbliam

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    Jul 24, 2015
    Thanks Bob that makes sense as a colleague in our department from some time ago wrote a guide to possible repairs and he had it down as 0.53 x 10 %.
    I shall order that value in next week , but what about wattage and type (carbon film 1/4w?)
     
  12. Martaine2005

    Martaine2005

    2,575
    695
    May 12, 2015
    Did you read all the posts?

    Martin
     
  13. ecurbliam

    ecurbliam

    5
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    Jul 24, 2015
    Yes I did Martin and reread them this morning .
    I don't see wattage mentioned but I
    I see carbon comp thankyou .
     
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