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Resistor value identification

Discussion in 'General Electronics Discussion' started by Nick Marino, Jan 31, 2015.

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  1. Nick Marino

    Nick Marino

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    Jan 31, 2015
  2. BobK

    BobK

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    Looks like green brown gold, which is 5.1Ω

    Bob
     
  3. Nick Marino

    Nick Marino

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    Jan 31, 2015
    probably not the best picture but I think its green black brown then the 4th I think is black which is throwing me off.
     
  4. BobK

    BobK

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    Green black brown would be 500Ω

    Black should not be allowed as the fourth band. But the fact that the 3 bands are together makes me think it is a 3 band color code.

    Bob
     
  5. davenn

    davenn Moderator

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    Sep 5, 2009
    looks more like green brown red ... don't see any gold band in there

    5100 Ω

    have you actually tried to measure it ??


    Dave
     
  6. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

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    Nov 28, 2011
    That resistor has obviously been running very hot for a long time. I wouldn't trust any of the colour bands to be their original colours, except perhaps the green one. Measure it, but unless it's within say ±10% of a value starting with 5, its measurement may be wrong as well.

    If you post some photos of the board that it came out of, we may be able to estimate an appropriate value.
     
  7. Nick Marino

    Nick Marino

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    Jan 31, 2015
    ok I will get a picture of the board and yes it ran very hot and I agree I don't trust the colors either. send an image of the board in a few minutes.

    I did try and measure it, I had my meter set on two hundred omhs and it read 5.56 out of the circuit. when I set it any higher than 200 I got no reading at all.
     
  8. n-ire

    n-ire

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    Jan 31, 2015
    Also by looking a the bending of the leads this resistor is NOT sized correctly. The wattage is way over-utilized. If and when determined its original value try a 10W+ in it's place, then scale down.
     
  9. Nick Marino

    Nick Marino

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    Jan 31, 2015
    That's not the original bending of the leads, I sent my wife to radio shack with to see if they had one the idiot there bent them straight. Then he told her to go to Ace hardware or Lowes to get one cause they hade more resistors than radio shack.


    here is a couple images of the board.
    https://onedrive.live.com/redir?resid=9F9074D3C9AAB530!2745&authkey=!AOg_rK0uwt6g4lM&v=3&ithint=photo%2cjpg

    https://onedrive.live.com/redir?resid=9F9074D3C9AAB530!2749&authkey=!AFLhVxBDWmc2QSw&v=3&ithint=photo%2cjpg
     
  10. n-ire

    n-ire

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    Jan 31, 2015
    On your seconds image there is a silk-screen outline for R4 - is this the resistor we are talking about? As I said before, start at wattage 10+ or more,and decrease by 1. You do not have to solder it in place of course, just has it made contact and see if your circuit works, and if the resistor gets warm. All resistors burn power and exchange energy from electrical to heat, and in your decade box you should have at least the basics: 1, 2.2, 5.1 and 6.8 - these should be at least 1W huge fellows, but having enough of them you could build resistors up to 9.1Meg of any value, only for testing of course ... for any circuits under single-phase 220V. 220 single-phase AC might kill you of course -
     
    Last edited by a moderator: Feb 1, 2015
  11. Nick Marino

    Nick Marino

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    Jan 31, 2015
    yes R4, also I was wrong about the reading I was getting,

    when I set my meter to 2k it reads 5.65 and when I put it on 200 I get no reading.
     
    Last edited: Jan 31, 2015
  12. n-ire

    n-ire

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    Jan 31, 2015
    Wow..get back on this one.., are you measuring in-circuit or out-circuit. In-circuit means soldered to the board, and you might be experiencing active load - since it is a failed device remove it and measure again.

    I would still go whatever I posted before - remove R4 and replace it with at least a 1W resistor of high value such as 10 or even 100 Ohms. , between the power supply and the PCB place a very low wattage resistor (Rx) such as a 1Meg 0.125W, and see how it goes. Again, replace RX by 100K down, and see if you get signs of life out of the PCB or blow the fuse (Rx). Wear safety glasses, or be blinded by science.
    Good luck!
     
    Last edited by a moderator: Feb 1, 2015
  13. Nick Marino

    Nick Marino

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    Jan 31, 2015
    No I am testing it out of the circuit, I am in the US too.

    the board is from a small air compressor. it connects to a pressure switch and to a 110 volt fan and the small compressor motor itself.
     
  14. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

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    Nov 28, 2011
    We may be able to estimate a suitable value for the resistor if we can reproduce the design. To do this, we need clear, clean photos of both sides of the board. You need to:
    • Move all the wires so they don't obscure any components
    • Clean both sides of the board - start with a toothbrush and a mild solvent (isopropyl alcohol aka tape head cleaner is ideal)
    • Remove any glue or other gunk from both sides of the board using a razor blade, screwdriver or similar
    • Make sure all components are clean and their identifying markings are readable
    • For the transistor that stands vertically, make a note of the markings on it
    • Take clear photos, preferably in outdoor light but not direct sunlight, of both sides of the board.
     
  15. BobK

    BobK

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    Jan 5, 2010
    I think this confirms by original post of green brown gold = 5.1Ω It measures close enough to be a 10% tolerance resistor of that value.

    Edit: If it is indeed reading correctly, it remains to be determined why it was burning up, replacing it is not likely to help.

    Bob
     
  16. davenn

    davenn Moderator

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    Sep 5, 2009
    HI Nick

    That's most likely 5.6 Ohms which is a standard value and BobK was close with his first 5.1 Ohm suggestions :)

    As Kris said, It can be very difficult to determine the colours when a resistor has got hot for some time

    200 what ? I will assume 200 K Ohm range rather that 200 Ohm range


    Dave
     
  17. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

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    Nov 28, 2011
    That doesn't quite make sense.

    Assuming you have a 3.5 digit multimeter, when you set it to the 2 kΩ range, it shows a value between 0Ω and 1999Ω, with no decimal point. It could indicate 565, without the decimal point, i.e. 565Ω, in which case the resistor may be supposed to be 560Ω.

    On the 2 kΩ range, a 3.5 digit multimeter cannot indicate "5.65". It could indicate "5.65" on the 20Ω range, if it has one, or the 20 kΩ range, or the 20 MΩ range, because on those ranges, it displays a decimal point with two digits to the right of it.

    Perhaps you could measure it again and take a photo of the meter so we know exactly what you're doing.
     
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