Multimeter testing

Discussion in 'Wii - Hacking' started by Dirtie, May 1, 2007.

May 1, 2007

Multimeter testing by Dirtie at 10:31 PM (1,296 Views / 0 Likes) 10 replies

  1. Dirtie
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    Former Staff Dirtie :'D

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    My electronics knowledge is a bit, err, limited, so I've got one quick question. I need to test the points in my Wii (without a chip installed - it's a long story) to see if my "repair" of a few points went ok (see here: http://psx-scene.com/forums/cyclowiz/54211...-sticky-me.html ).

    However, I'm always confused a little by multimeters. Firstly, which setting(s) should I have it on? Mainly I'm checking the connection between the solder points and the legs of the DVD drive chip, and also for bridging between each of the points. Secondly, if there is any connection at all thanks to my repairs, how do I find out if the connection is good enough (ie. has a low level of resistance)?

    It seemed a whole lot simpler when I was back in school and had to make a simple continuity tester with a little LED that lights up [​IMG]
     
  2. FAST6191

    Reporter FAST6191 Techromancer

    pip
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    An ohmeter (any range but make it small (ohms or less) will do), should the resistance drop to zero or near enough (the system before you even touch anything has some resistance) you have continuity (good for repairs bad if you are testing for a bridged connection).

    It should just be signals which usually have a reasonable safety factor (they will be 10-20% above critical) but provided any resistance is in the ohms range you have no worries.

    Oh and if you wondered here is a shot of a generic multimeter (90% of the time they are the same) with the settings you want:
    [​IMG]
     
  3. Dirtie
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    Former Staff Dirtie :'D

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    Well that is indeed the setting I was using. Which brings me to my next point - I think one of my repaired points was 1.1 (whereas the intact ones read something like 0.0~0.4)

    Is this too high?

    Edit: Just tested my "repair" again: One point was indeed 1.1, one was just under 20 and the other one was ~90 [​IMG] I'm guessing this isn't good enough?
     
  4. FAST6191

    Reporter FAST6191 Techromancer

    pip
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    If it is on the setting I circled then that is a whole Ohm difference, put it this way if you are that bothered shave about 50cm from your wire to make up for it.

    They do sound a bit high, tap the solder with an iron to melt and refreeze it.
     
  5. Dirtie
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    Former Staff Dirtie :'D

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    The problem is that it's not solder though [​IMG] Just a conductive silver mixture. I might try tinning them with real solder (if it's possible) and see where that gets me.

    For more details on what exactly went wrong: http://gbatemp.net/index.php?showtopic=458...ndpost&p=639766

    So damn annoying >_<

    Edit: Hmm, I attempted to tin my repaired points, but it only worked for the one that had a half-decent reading - it just lifted the silver stuff right off the others [​IMG]
     
  6. craig588

    Newcomer craig588 Advanced Member

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    Once you've ripped the points off don't bother trying to repair them with a conductive pen, they're never going to work well. (As you've experianced with the high resistance) Solder directly onto the legs of the chip instead and all will be well.
     
  7. Dirtie
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    Former Staff Dirtie :'D

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    The chip legs are really a last resort.

    I did manage to get all three points in the range of ~1 to ~2 - I really need to know if this will be good enough. The silver compound isn't like solder, you can move the multimeter probes around and the resistance can change quite a bit.
     
  8. FAST6191

    Reporter FAST6191 Techromancer

    pip
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    I assume you have pin ended probes make sure you push down a little (or scratch the surface a bit) as surface resistance (courtesy of oxides or rubbish) is likely a bit higher than internal.

    1 or 2 ohms really is nothing to be concerned about, I probably would not be that fussed at 90.
     
  9. craig588

    Newcomer craig588 Advanced Member

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    I work repairing arcade machines, that's why we never use it, it's very, very difficult to get a good connection. On signal lines (depending on the frequency and how close to tolerances the hardware's running) even 1 ohm can sometimes be too much. If you're worried about killing the chip from heat when you solder on the legs you don't need to worry, everything on that board was heated to hundreds of degrees before it was installed.

    I'm not trying to be negative, I'd love if it was simple to repair stuff like that, but usually it doesn't work out and I don't want your mod chip or drive to get killed because of a bad connection from a signal line where something get's a bad command and makes it do something crazy.
     
  10. Phrostay

    Newcomer Phrostay Advanced Member

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    This will sound rather simple but how do I tell if a signal/piece of wire is working correctly. i.e. I have tinned both ends of a wire with solder and want to test how much resistance etc. their is. Can a multimeter do this for me?
     
  11. FAST6191

    Reporter FAST6191 Techromancer

    pip
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    Yeah the settings in the picture above are for resistance, simply put the two probes on either end of the wire.
     

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