Is my pad-234 analog/digital trainer damaged

Discussion in 'General Electronics Chat' started by janette, Apr 8, 2011.

  1. janette

    Thread Starter New Member

    Apr 8, 2011
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    I have a pad-234 analog/digital trainer which smoked and sparked backed to back with about 1/2 minute in between each occurance. I followed the instructions before performing the assignment. I was performing the reading of the current from the voltage from one resistor to another.
    My professor said i blow a fuse in the dmm reader because i could no long get a correct reading. I replaced the fuse in the dmm and it worked fine on two assignments, but during the third assignment the dmm fuse blow out again. I am following instruction, so I think its the breadboard. I believe that when it smoked and sparked iit damaged the pad-234 analog/digital.
    Am I correct. I can not afford to keep replacing the fuse in the dmm reader.
    where am I going wrong.
    Please help.
     
    Last edited: Apr 8, 2011
  2. retched

    AAC Fanatic!

    Dec 5, 2009
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    Without photos and/or video, and wiring diagrams/schematics to see EXACTLY how the breadboard is wired and how the components are laid out, there is no way for us to tell what happened from your explanation.

    Did you change the probe inputs on the DMM to check current?

    Most DMMs require you to unplug the RED(+) probe and connect it into another special input. Many have more than 1 extra input for higher current.

    If you were reading voltages across a resistor, in a proper voltage mode, then that should be trivial.

    Did you check the OLD fuse to see if it was blown after you removed it?
     
  3. mbxs3

    Active Member

    Oct 14, 2009
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  4. janette

    Thread Starter New Member

    Apr 8, 2011
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    I guess what i am really trying to find out to make a long story short is was the pad-234 analod/digital trainer damaged when it smoke and sparked underneath the breadboard. is it pssible this is what is causing the problem i am preently having with my fuses blowing in the dmm?
     
  5. SgtWookie

    Expert

    Jul 17, 2007
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    Your DMM fuses are blowing because you are attempting to read current across the power supply, causing maximum power supply current to flow through the meter. You may have damaged the power supply in the pad-234 analod/digital trainer along with blowing the fuses in the DMM.
     
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  6. janette

    Thread Starter New Member

    Apr 8, 2011
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    Sgt.Wookie, please tell me how did you reach that conclusion? i have been asking so many to help me solve this problem including my professor and none of the could figure this out.
    how am i managing to do this. I built series and parallel circuits per my assignment to read individual and total current. the first two times i did this i was fine, but the thir time i attemted the current reading the fuse blow.
    please help me to correct this matter, so i may sop blowng the fuse.
    oh do i need to have the breadboard serviced.
    pleae forgive me if i sound slow to the issue. i am a beginner at this. this is my 1st class in my major subject (comp & elec. Tech.) online.
     
  7. R!f@@

    AAC Fanatic!

    Apr 2, 2009
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    Simple..the only way to blow a DMM fuse is connect the meter in ammeter mode to a voltage source and KAPOOOW!!!

    Can you show any pictures
     
  8. SgtWookie

    Expert

    Jul 17, 2007
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    Many years of experience with multimeters and DMM's.

    Basically, if you place the meter's leads across a potential that is capable of supplying more than about 250mA, you will blow the meter's fuse.

    It really is not rocket science. The meter in mA measure mode has a very low internal resistance. It measures the voltage drop across this low resistance. If the current through the resistance exceeds around 250mA, the fuse blows rather than destroying the meter.

    You need to stop trying to measure how much current the power supply can output. It is hard on the supply and meter, and will cause you to go through a lot of fuses.
    I think you are confusing reading total current with measuring the voltage across the supply. If you are reading the circuit total current, the meter needs to be in series with your circuit, not from the supply+ to the supply-.

    You did something different the third time, then - or perhaps the power supply became defective, and was putting out far too much voltage, which would mean excessive current through your circuit.

    please help me to correct this matter, so i may sop blowng the fuse.
    oh do i need to have the breadboard serviced.[/QUOTE]
    Measure the VOLTAGE across the power supply. If it reads within specifications, it might be OK.
     
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