Lc meter not working

Discussion in 'General Electronics Chat' started by takao21203, Jul 5, 2014.

  1. takao21203

    Thread Starter Distinguished Member

    Apr 28, 2012
    3,577
    463
    Bought a PIC18 based LC meter some time ago,
    it has a Nokia5110 display which so far, works.

    Power supply is 9v jack, I soldered a 9v battery with wires.
    There is a 78l05 and also AMS1117 3.3

    The LCD menu works 100%, however, neither caps nor inductors can be measured at all.

    Sometimes erroneous values show, sometimes it stays at zero.

    I tried around a lot, but to no avail.

    Is it broken maybe, or a wrongly soldered component?
     
  2. THE_RB

    AAC Fanatic!

    Feb 11, 2008
    5,435
    1,305
    What is the oscillator? Normally they have an external opamp or comparator oscillator?

    Photos and a schematic would be a massive help here!
     
  3. takao21203

    Thread Starter Distinguished Member

    Apr 28, 2012
    3,577
    463
    I guess the internal comperator from the PIC18 is used.

    There is no schematic included, but yes, I can post a photo shortly.

    Checked solder joints of course but did not find any faults.
    my guess is a swapped resistor perhaps.

    Why didn't they check it before shipping? I sent ebay message but no reply, typically with these chinese reseller megastores.
     
Loading...