Troubleshooting R-Series Detectors

Below are some suggestions for correcting problems with your R-Series Detector. Please email  or call us at +1 (360) 764-8850 if you are unable to correct the problem.

Detector does not turn on

Sometimes, you may turn on an R9500 or R8000 Coded Wire Tag detector and nothing happens. This is likely a detector power problem. Here are some tips that may help.

If none of the LEDs to the left of the threshold light up, then the detector is not getting power. Check the following:

  1. If powered with C-cell batteries, check that the batteries are fresh. If the batteries are low then the low or dead battery light should be lit on the front of the detector. Fully exhausted batteries will not light the low battery LED.
  2. If powered with a 12V battery, check that the battery is charged and that the cable between the battery and the power connector on the back of the detector is properly connected. A 12 volt battery is considered fully charged at 12.9 volts and fully discharged at 11.4 volts.
  3. If powered with the NMT 15V power supply, check that the cable is properly attached to the power connector on the back of the detector. If you are also using a gate, then the NMT 15V Power Supply must be attached to the power input connector on the gate, and the gate cable must be attached to the electronics connector on the back of the detector.
  4. If you are using an extension cord, check that it is working properly.

Counter Troubles

The quad counter keeps track of four groups of fish running through an R-Series Tunnel Detector. It is usually trouble free, but things can go wrong. Here are some ideas for troubleshooting. 

If the Quad Counter isn’t counting:

Combined Quad Counter and Subsampler

Combined Quad Counter and Subsampler for R-Series Detectors

  1. If the counter has leading zeros, then the battery is low or dead and the counter must be returned to NMT for  replacement. The battery should last for many years. You can prolong its life during storage by removing the cable attached to the back of the counter. The battery will drain when the cable is attached to the counter without the probes being in the gate.
  2. Make sure the counter cable probes are seated all the way into the holder on the gate, and secured with springs. If the springs are missing, they can be replaced with elastic bands, or contact NMT for replacements.
  3. If you attempt to increase or decrease the count when the cable is attached to the back of the counter, but the probes are not in the gate, then the counter won’t work. If you remove the cable or if you seat the probes into the holders on the gate, then the counter will count.
  4. If one is available, use a different counter cable to determine if the problem is with the counter or the cable.

If the Quad Counter keeps counting when you aren’t running fish:

Water may have seeped under the switch and corroded the contacts. Please contact NMT for assistance.

If counts accumulate on the opposite side from the gate diversion:

The left and right cables from the counter to the gate look identical. If you open the left door and it counts on the right, simply switch the probes and reseat them with the springs or elastic bands. Reset the counters to “0”.

Fish are diverting the wrong way

There are several reasons why fish may be incorrectly diverted, and in most cases, the problem can be corrected by the operator. 

  1. Verify that you have set the detector so that the default gate position (the side where untagged fish will go) is properly set to the side where you would like them to go.
  2. Check that the bent ends of the small spring under the gate box that goes through the latch hook are not interfering with the movement of the latch hook.
  3. If using a 12V NMT battery, check that it is fully charged.
  4. Verify that all four rubber bumpers are in place on the gates. The bumpers align the gates, and if any are missing, then the fish may not divert properly. (See R-Series Instruction Manual (pdf) and the R-Series Seasonal Checklist (pdf) for more details about the bumpers.) Contact NMT if you need replacement bumpers.
  5. Make sure that every fish is sent through the detector head first if you are looking for tags in the snout.
  6. Make sure that the fish are going through the detector at the right speed. We recommend that you attach running water to the detector and that the fish move through at about 1 meter per second. Without water, the fish may get stuck in the detector and the gate will open and close before the fish gets to the gate, and will be incorrectly diverted.
  7. Fish with hooks or other metallic objects may be incorrectly diverted.
  8. Proper gate function requires that the delay and duration are appropriately set for your sampling session. The delay is the time lag between when the tag is detected at the center of the detector and when the gate opens. The duration is how long the gate stays open. If these are not adjusted for the speed with which you are throwing fish through the detector, then the fish will not divert correctly. Learn more about gate settings (pdf).
    1. Start with the delay knob set all the way counter clockwise (minimum) and the duration knob set all the way clockwise (maximum). These settings accommodate the usual speeds of fish pushed through the detector with running water and with a slight separation between fish. Pass a tagged fish through the detector to verify these settings are right. If your fish are being correctly diverted, leave the settings as they are.
    2. If your fish are moving more quickly or if more than one operator is putting fish in the detector, you may need to increase the delay and decrease the duration. Slowly adjust the delay and duration to get the timing correct.

Alarm Malfunctions

R-Series Tunnel Detectors are designed to detect Coded Wire Tags and signal a loud alarm and light when a Coded Wire Tag is present inside the tunnel. When the detector alarm doesn’t work, these tips may help you pinpoint the issue:

No alarm sounds when a tag is present

  1. Verify that the detector is turned on and that power is getting to the detector.
  2. Check that the Sensitivity knob is set at about 10 o’clock and then run the tag standard through the detector again. If there is still no sound, check to see if the LEDs go above threshold on the front panel of the detector as the tag is passed through. If the LEDs light up and there is no sound, then the alarm may be faulty. If the LEDs do not light up, then there may be a problem with the detector.
  3. The tag may be moving too slowly through the detector. Test this with the tag standard – move it quickly past the detection area, which is roughly in the center of the tunnel. If the detector works in this case, then increase the water flow through your detector, and push the fish through more quickly.

An intermittent alarm sounds when a tag is not present

  1. Is the detector on a wobbly stand? Too much motion may set the detector off. Stabilize the stand using non-magnetic supports such as wood or plastic sawhorses.
  2. Is the detector near motors or near 60Hz power lines? Move the detector to a different location and see if the problem persists.
  3. Check the desiccant. Is it pink at the end attached to the detector? If so, there is moisture in the detector and this may be causing the problem. 


R9500 showing detector desiccant and gate

The detector desiccant is mounted on top of the detector, inside the back carrying handle.

R-Series Tunnel detectors (R8000 and R9500) use external desiccant cartridges to protect the electronics. The detector desiccant is in a plastic cylinder mounted inside carrying handle at the back of the detector. One hose is connected from the desiccant cartridge to the back of the detector and the other hangs loosely.

Here are some tips for dealing with your detector desiccant:

  1. Pink indicates moist (exhausted) desiccant. Blue indicates dry, fresh desiccant. Change the desiccant when it is 3/4 pink.
  2. If the desiccant is pink at the end attached to the detector, it means that there is moisture in your detector. 
  3. Store the detector in a dry place with the desiccant cartridge attached. Continue to check the desiccant during storage.