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Thread: Optical Sensor Troubleshooting

  1. #1
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    Optical Sensor Troubleshooting

    I suspect that I may have an optical sensor going bad on me. I purchased an ATK last summer (shortly after they came out) It was working fine, then shortly after installing my COR20, the upper optical sensor started funny (see this thread) Now a few days ago, the upper optical sensor started reading closed even though it was out of water and hadn't been covered (or even splashed) to my knowledge.

    The sensor appeared clean, but I tried wiping it off with no change. I then unplugged it from the FMM and plugged it back in which fixed the issue.

    The inputs on the FMM are manually set to optical sensor and autodetect is unchecked.

    My potential theories are:

    • wire cross-talk/interference (I have most of my optical sensor and probe wires bundled together (Edit: The power cable for the COR is separate from the sensor wires)
    • Hardware/firmware issues with the FMM (it's updated with the newest firmware)
    • A physical/mechanical issue with the optical sensor. I can't see anything obvious, but a small fracture in the wire insulation or the sensor housing could let humidity get in, causing a short.


    At this point, the issue is very intermittent, making it difficult to tell what's causing the problem, but I also need to be able to rely on the system; an unreliable sensor is worse than having no sensor at all. Does anyone have any suggestions for troubleshooting this?

  2. #2
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    I had one optical sensor that sent false warnings shortly after installing a COR-20 and turning off auto-detect and making sure the sensor wires were away from the COR and all other wires fixed the sensor problem.

  3. #3
    Frequent Visitor rkpetersen's Avatar
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    When the low sensor on my ATK went bad, it did exactly what you're describing. Intermittent at first, then eventually became completely stuck in the CLOSED position. Inspection of the sensor showed some brownish material leaking from where the cord meets the sensor body.

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    Quote Originally Posted by rkpetersen View Post
    When the low sensor on my ATK went bad, it did exactly what you're describing. Intermittent at first, then eventually became completely stuck in the CLOSED position. Inspection of the sensor showed some brownish material leaking from where the cord meets the sensor body.
    That's what I'm afraid of - I'll end up spending a bunch of time dealing with a glitchy sensor that I can't rely on until it finally reveals itself and goes bad.

    The annoying thing is that this sensor hasn't even been in water that much - it's the high level sensor that only gets wet when the sump level rises.

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    Quote Originally Posted by Sleepydoc View Post
    The annoying thing is that this sensor hasn't even been in water that much - it's the high level sensor that only gets wet when the sump level rises.
    When it comes to plastic corrosion (cable insulation is a softer variation of PVC), that is actually worse for it. Water gets in tiny cracks, then when it dries crystals form and expand slightly making the opening slightly bigger, process repeats over and over. Something continuously submerged never dries out to expand the cracks.

    You might be an engineer if...You have no life and can prove it mathematically.

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    Never thought about it, but with salt water, it's could be kind of like a reverse freeze-thaw cycle on the roads. Of course, that assumes that the salt crystal precipitant takes more space than the water that deposited it, so who knows.

    Either way, if that is an issue then it means the sensor is not suitable for its intended use.

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    Quote Originally Posted by Sleepydoc View Post
    Never thought about it, but with salt water, it's could be kind of like a reverse freeze-thaw cycle on the roads. Of course, that assumes that the salt crystal precipitant takes more space than the water that deposited it, so who knows.

    Either way, if that is an issue then it means the sensor is not suitable for its intended use.
    Its not that its not suited for that use, that would be a manufacturer defect if it does do that. They are supposed to be fully sealed with no cracks but if there is one that process can occur.

    You might be an engineer if...You have no life and can prove it mathematically.

  8. #8
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    I am having the same problem.
    I just installed the Two Cor20's and now a week later I am starting to think they are the problem. I have tried to reroute the wires a couple of inches away from each other.
    I still am having no luck. Unfortunately, I might have to pull them out of the tank and troubleshoot them.
    I believe there may be some interference between the Cor20 wires and the optical sensors since this is affecting my overflow sensors as well.

    The overflow sensors worked until they sat in water for an hour. Then they corroded away to nothing so I am not sure if electrolysis is the culprit or what.

    I will be contacting NEPTUNE SYSTEMS about this issue. I will probably also contact BULKREEFSUPPLY since that is where I purchased everything.

    AND Yes I am an engineer. These products are not holding up to their high reputation.
    I am in the process of building my own "SYSTEM" based on PYTHON and arduino and Raspberry Pi modules.
    I know it will be cheaper to build my own system since all of these sensors are available on the arduino platform.
    Its just a matter of the interface that will be hard to replicate.

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