fault finding insulation resistance meter

Discussion in 'The Projects Forum' started by ninjaman, May 28, 2016.

  1. ninjaman

    Thread Starter Member

    May 18, 2013
    306
    1
    Hello,

    I bought two meters from ebay the other day both are insulation resistance meters. The digital one is faulty, I put in fresh batteries and nothing. No battery check light or anything. I want to fix it but not to sure how to fault find. I took it apart and had a look at the capacitors, nothing had popped or swelled. There doesn't seem to be any sign of burning anywhere or poor solder joints. I want to fix this thing, how could I go about it. Please do not answer four year degree course or read a massive book like the art of electronics. I think that measuring voltages around the circuit may be a start. However, recently I tried to fix my signal generator, the 1kHz velleman kit. There is no output, the circuit works up to a point on the board but it doesn't get to the output. I am not sure if a capacitor may be the problem.
    The insulation resistance meter is 12 volts. I think I know enough about safety to not shock myself or possibly blow something up. What suggestions for fixing this thing. There are a few chips on the board.
    Any advice would be great!

    Thanks

    Simon
     
  2. DickCappels

    Moderator

    Aug 21, 2008
    2,651
    632
    You might obtain more of a response if you can include some information about the meter itself, such as model number and manufacturer. A photograph or schematic would also be helpful. With the information in your post, the best you would get is guesses.

    Who made it, what is the model?
    Can you post a photo of it?
    Can you post a schematic?
     
  3. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,518
    2,369
    Did you purchase them as working cond? if so you have a come back on ebay/paypal.
    Insulation meter's generally produce a high voltage in order to stress test the insulation.
    The old hand crank Meggers produced 500v or 1kv selectable.
    Max.
     
  4. ninjaman

    Thread Starter Member

    May 18, 2013
    306
    1
    Hello,
    This is the same model as the one i have.
    [​IMG]
    I also have the hand crank one, that came as part of the sale.
    I dont have a schematic unfortunately, just this picture. I cant find anything online except for an operation manual. I have the Robin one pictured, though there are other brands with exactly the same spec and look.
    is there not a generic fault finding process?
     
  5. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,518
    2,369
    Yes look for the dark brown overheated resistor.;)
    Max.
     
  6. AlbertHall

    Well-Known Member

    Jun 4, 2014
    1,912
    379
    Measuring the voltages only helps if you know what the voltages should be.
    My process for this sort of thing goes something like:
    Inspect very carefully for any components that appear damaged/overheated/badly soldered.
    Look up any ICs, transistors, etc so you know what they are and what they do.
    Understand what the thing is trying to do, and what functions may be supplied by the various components on the board.
    Now you can measure some voltages to check your understanding. If you find something wrong then you may have to trace out (part of) the schematic to further your understanding.

    It is not easy fixing things where you don't have a schematic and nigh impossible if you don't understand the things function.
     
    Last edited: May 28, 2016
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