What can be the result if a resistor has less resistence in circuit?

Discussion in 'General Electronics Chat' started by frank55, Dec 5, 2015.

  1. frank55

    Thread Starter Member

    Dec 6, 2013
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    Hi guys if i have a SM resistor that should measures 100K and only measures 4K inm circuit on a power supply, what would be the symptoms?
     
  2. kubeek

    AAC Fanatic!

    Sep 20, 2005
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    You just said that, the symptoms are that you are measuring 4K instead of 100K. The reason most likely is that there are other elements in the circuit which means you are not mesuring only the resistor but a whole bunch of other components as well. Try taking it out of the circuit and measuring again.
     
  3. frank55

    Thread Starter Member

    Dec 6, 2013
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    thanks but if i take it out and it measures only 4K instead of 100K ?also i have another same 100k in parallel and it gets the right resistance which is about 100K
     
  4. dl324

    Distinguished Member

    Mar 30, 2015
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    Other resistances in parallel with the 100K resistor... Remove one end to get an accurate measurement.
     
  5. dl324

    Distinguished Member

    Mar 30, 2015
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    It would help if you posted a schematic.
     
  6. bertus

    Administrator

    Apr 5, 2008
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  7. dl324

    Distinguished Member

    Mar 30, 2015
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    Ah! SM in this context means Surface Mount, not SMall... I've never seen them referred to as SM; only SMT and SMD...

    Obviously lifting one end is not possible...
     
  8. frank55

    Thread Starter Member

    Dec 6, 2013
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  9. ian field

    Distinguished Member

    Oct 27, 2012
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    As everyone else mentioned - other components will conspire to give a low resistance reading in circuit.

    Usually - resistors are more likely fail by going open or high resistance - if it read high in circuit, you'd know there was a problem.

    Its not impossible for a resistor to fail low - but they usually show signs like scorching.
     
  10. frank55

    Thread Starter Member

    Dec 6, 2013
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    thanks
     
  11. WBahn

    Moderator

    Mar 31, 2012
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    If they are truly in parallel, then you should be getting the same measurement for both. Why? Because they are in parallel!

    So it's pretty clear that they are NOT in parallel. What makes you think they are?
     
  12. frank55

    Thread Starter Member

    Dec 6, 2013
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    Thanks WBhn; well i'm not 100% sure, maybe you can figure it out for me and help, this is an LCD Samsung Monitor 2493 HM that i found out in the curve on the street,it has a steady blue light when i turn it on with black screen, i have no 24v to inverter and no 5.3v to the main board ,

    so i took out the power supply board and connect by itself , the Big black Cap in the middle has 167v and IC801S pin 2 cc to gnd 10.60v it's too low i think ,i also cleaned all the hard glues that some say it's an issue.

    checked all caps with a CapAnalyzer 88A and all other components that can be checked with a Fluke 87 DM and nothing seems to be out of order,

    here some pic of the power supply.
     
  13. frank55

    Thread Starter Member

    Dec 6, 2013
    253
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    Hi WBahn; any more tips on this power supply fault? thanks
     
  14. frank55

    Thread Starter Member

    Dec 6, 2013
    253
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    H guys new update on Samsung 2493 HM monitor.

    Today i decided to reassemble power supply after taken out Cap 4pf 1KV
    clean hard glue and re-solder it back also cleaned all other glue around all other caps,
    and for my surprise i have tv on but with no controls and just a screen with switching back and forth between RGB ,white,and blue screen,with no controls on the front,just power on and of switch,see video,
    what do you see of this?

    I connected HDMI cable and i get sound also

     
    Last edited: Dec 7, 2015
  15. frank55

    Thread Starter Member

    Dec 6, 2013
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  16. frank55

    Thread Starter Member

    Dec 6, 2013
    253
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    You don't have to bother with my monitor no more,i found a bad solder and fixed it.
     
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