multimeter drains circuit?

Discussion in 'General Electronics Chat' started by jarwulf, Mar 25, 2014.

  1. jarwulf

    Thread Starter Member

    Jul 7, 2013
    I have my multimeter set to 2 on DC voltage and trying to measure suspected voltage drop from the positive prong of a power jack to a point further along in the positive wire across some junctions in a circuit board. The module I'm measuring is powering on as indicated by an led but does not seem to be getting enough power to perform its function.

    For some reason it seems to shut off the circuit sometimes when I press the probe to the power jack and then comes back on when I take it off. I jiggled around the wires without the multimeter and it didn't seem to shut off then. The voltage is supposed to be around 8-7 volts. The PSU can supply 2 Amps. What could be wrong?
  2. pwdixon


    Oct 11, 2012
    Post a photo of your setup and perhaps a schematic and someone might be able to point at something.
  3. Alec_t

    AAC Fanatic!

    Sep 17, 2013
    Depending on what the circuit is, the meter impedance may be such as to modify circuit performance. Instead of measuring between A and B, try measuring between A and ground and between B and ground then subtracting the results.
  4. Zerotolerance


    Sep 18, 2011
    Don't skimp on tools. Buy a nice multimeter. When it comes to my tools, I do not skimp. I buy the best or as close to the best as I can afford.

    I own nothing but Fluke products for that simple reason. Skewed erroneous readings will screw you in the long run. Especially when working with electronics.
  5. BillB3857

    Senior Member

    Feb 28, 2009
    What holes do you have the leads plugged into on the multimeter? If plugged into the holes for measuring current, it can possibly short out the power supply.
  6. MrChips


    Oct 2, 2009
    You'd think it would have blown the meter on first contact.
  7. BillB3857

    Senior Member

    Feb 28, 2009
    All depends upon which hole he plugged in to. Some multimeters have a length of very heavy wire between the AMPS and COMMON holes. Taps on that wire then measure millivolts and indicate AMPS. Remember the old Simpson 260's?
    GopherT likes this.