Locate Faults With The Leakseeker-89R

Have you ever needed to hunt down a short circuit, but you’ve had no idea where it is or how it’s happening? As it turns out, there are tools to help in that regard. Enter the Leakseeker-89R.

The device is able to help hunt down short circuits that measure anywhere from 0 to 300 ohms. The device is typically used with two leads on a given pair of traces, and it has a display made up of red, yellow and green LEDs. As the leads are moved closer or farther from the short circuit, the display changes to indicate if you’re getting hotter or colder. There’s also a third lead that can be used to allow testing under more challenging conditions when there is a large capacitance in-circuit with the traces you’re testing.

Fundamentally, it’s basically a very accurate resistance meter, finely honed for the purpose of hunting down short circuits. We’ve featured similar tools before. They can be of great use for troubleshooting. Meanwhile, if you’re building your own test tools in your home lab, don’t hesitate to let us know! We’re always dying for hot tips on the best DIY lab equipment for saving time, frustration, and money.

29 thoughts on “Locate Faults With The Leakseeker-89R

  1. Would love an acoustic output where the resistance measurement changes frequency like in the tone ohm(?). That makes finding shorts much easier, because you can concentrate on the probing and don’t need to constantly look up to get the reading.

    Especially useful in tight places or when you’re unsure wether you actually punctured the surface oxide or not.

    1. Good idea!
      Some refinements:
      – Short probes for zero setting with a zero button.
      – Set a ‘far’ point to get it into range with a separate button.
      – When getting closer tone will increase up to 1khz or so meaning 0 ohm short
      – When getting farther than the closest point recently measured do a low beep of 100hz or so. Hysteresis maybe 1-10% to prevent bad connection/oxydized/conformal coating?
      – Use a synth chip/dac to play a note instead of a square wave beep :)

      Or just use voltage injection and thermal imaging camera :)

      1. The probe length doesn’t matter as the unit is self-calibrating.
        The range window is automatically selected by the micro.
        The tone will change up or down depending on your proximity to the short.
        The range is 0 – 300R but the reading is always relative to the previous reading.
        There is hysteresis built in. Probing a point longer than around a second will cause the unit to recalibrate the reading if necessary.
        A synthesized beep can always be done (for more money) :)
        I could include thermal imaging (for a lot more money) :)

    2. I took your “tone ohm[?]” bit as making a partial joke that while the tone frequency is altered, the “tone” would in fact be someone say “ohmmmm”, pitched up or down accordingly.

      My first thought was that the leading “ohm” bit would need repeating instead of pitching a constant “mmmm” loop up/down based on the distance to the short. So naturally my 2nd thought was a slow to rapid repeating of a simply “ohm” sound file, pitched up/down as needed, for some added laughs [and annoyed bystanders].

    1. Yeah…it’s a bit more sophisticated than an ohmmeter. It’s better described as a Computer controlled, auto-ranging, 0-300R relative reading Micro-ohmmeter with 16-bit DAC and audio-visual output. (Just rolls off the tongue…) :)

  2. Just in case there was any doubt, the Leakseeker-89R is a relative-reading micro-ohmmeter. It automatically finds a match between the resistance seen at the probe tips and an internally generated value. It outputs both a visual display of LEDs and an audible tone that changes based on the proximity to the short. A microcontroller and 16-bit DAC automatically find the correct measurement window to use and will update as the user probes around the short.

  3. Not to diminish this project, but there has been an off the shelf product for decade(s) that achieves the same result and for relatively low $ ($36.90 USD). I happen to find this device mentioned in an old electronics article and so I bought one… and have been extremely impressed at how well it works along with a ridiculously long battery life (years and years). So… if you do not want to DIY or need some of the functionality of this project… then check out the “Circuit Probe Model 105”:


    1. The Leakseeker-89R is, admittedly, a niche product. It has a single purpose but does that job extremely well. Just as there are many tools that can do a particular job, you will quickly find out that only a few of them do the job well.

  4. David, what is the test current and compliance voltage?
    Can you please mention that in the specs. One place mentioned it will not damage 3.3V IC’s but I imagine people using this tool to troubleshoot graphics card shorts and they are quite low voltage IC’s.

    I prefer many mA and a voltage below what will damage IC’s.
    Modern multimeters are a wimpy 1mA and just under 3V. Brymen are even less current ~0.3mA and not good enough IMHO to punch through oxides and passivation layers.

    Just bought a vintage DMM with 4mA test current, old Simpson 260’s could use 100mA (on 200 ohms range)- which made these legendary for use out in the field, outdoors, rain , dirt, rust, dealing with real-world wiring and connectors. Not a cozy lab bench.

    Wish you the best in your project, it looks really useful.

    1. Hi Kelly,
      The Leekseaker-89R is a rework of the original EDS-89 from EDS inc. and was designed by Dave Miga. He gave me permission to do a rework of the PCB layout. I incorporated some additional stuff such as battery operation and sized it to fit a Hammond case. There is a test circuit built into the front panel. I didn’t design the circuit. That said, the output voltage is around 2.5v and current 8 – 16mA depending on the value of the short (0-300R).

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