Sholdering issues

Discussion in 'General Electronics Chat' started by legolas11, Mar 20, 2013.

  1. legolas11

    Thread Starter Member

    Feb 26, 2013
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    I never sholdered a circuit before. So i checked the circuit in bread board and after everything ok i sholdered it. After finishing the job and before connecting to power and placing IC, i checked the resistor and capacitor values using multimeter. Here i found couple of mismatches.

    1. 2 of the resistors(10k) showing half value. i replaced with new but it remained same.
    2. some capacitors(.1u) are showing more than its value, to be precise nearly double. and some showing 1(i assume very high value).

    Am i not supposed to get the original value (even though they are in a circuit) because i did not supply power??
    So does it mean i have done something wrong in shouldering the correct circuit???
    Is there any other better way to know whether i damaged them while sholdering??

    Thanks in Advance

    Note: for capacitence checking i used the multimeter
     
  2. tracecom

    AAC Fanatic!

    Apr 16, 2010
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    Most of the time, you do not get accurate resistance and capacitance readings using a mulitmeter on components that are connected in a circuit. This is because the meter reads the entire circuit instead of just the one component you are trying to measure. To accurately read an individual resistor or capacitor, you would have to disconnect one end of the component from the rest of the circuit, and then measure it.

    Usually resistors and capacitors are not damaged during soldering unless they are extremely overheated. If the solder joints are bright and well filled and there are no visible signs of heat damage to the component or around the joint, then there is probably no damage.

    Give it a good visual examination, recheck the connections compared to the schematic, and apply power. Watch for any signs of trouble such as smoke, overheating, and hope for the best. It may just work as planned.

    And it's spelled soldering, not shouldering. :)
     
  3. @android

    Member

    Dec 15, 2011
    178
    9
    You are measuring effective resistance & capacitance, probably two resistors & two capacitors in parallel.

    In-circuit values of components may not be accurate. Most of the time you may measure resistor correctly but no guarantee.

    Hope that helped.
     
  4. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    spelling police are here..:) please pull over to the side of the road
    soldering not sholdering
     
  5. shortbus

    AAC Fanatic!

    Sep 30, 2009
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    Unless he is Atlas and it's a really big circuit. :)
     
  6. takao21203

    Distinguished Member

    Apr 28, 2012
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    SMDs easily go crap from desoldering.

    Leaded components can be cut off sometimes for instance MOSFETs, or you risk to ruin the via's as well.

    Only SMD ICs are really easy to desolder.
     
  7. legolas11

    Thread Starter Member

    Feb 26, 2013
    55
    0
    Thanks a lot for all the reply and sorry for the wierd spelling.
    I have checked and did not identify any damage related to overheating. And i desoldered one of the resistances and found it is giving the correct value then. So i assume its because of being in a circuit they are not showing correct value. I have a question then, pardon me if it is a dumb question.
    Why on the breadboard the resistances show the correct value but not in a stripboard, even though in both cases the component are part of circuits. The difference between breadboard and stripboard to me, one is fixed and the other is not. Correct me if i am wrong.
     
  8. Metalmann

    Active Member

    Dec 8, 2012
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    Can't say for sure, but it seems that you should get identical readings.:confused:
     
  9. kubeek

    AAC Fanatic!

    Sep 20, 2005
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    If the circuits are identical, you should get the same values. Except for very low value resistors like 0.22R which will probably be a bit different on a breadboard because of the resistance of the contacts.
     
  10. legolas11

    Thread Starter Member

    Feb 26, 2013
    55
    0
    ya....you are right. the variation in res value occured from unexpected short connections. After repairing those connecttions the res value are showing perfectly.
     
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