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Troubleshooting guide

This document is intended as a means to solve issues with Medusa spectrometers. It is by no means complete.

Different hardware configurations

Medusa sensors may contain different hardware configurations. The first step to solving issues is to identify the hardware configuration:

Detector electronicsSerial numbersDefault IP address
https://radiometrics.atlassian.net/wiki/spaces/TI/pages/6881559SO-4200.17A-0001 to SO-4200.17A-0007192.168.2.100
https://radiometrics.atlassian.net/wiki/spaces/TI/pages/6881547SO-4200.17A-0008 to SO-4200.17A-0029192.168.2.101
https://radiometrics.atlassian.net/wiki/spaces/TI/pages/6881551SO.18.B.0030 onwards192.168.2.150

Data is coming in, but the spectra are empty

  • For mMCA v2 systems: Check if spectra are coming in at the web interface (http://192.168.2.150:8000)
  • For older systems: Check the high voltage settings in MASS / SODL. Try voltages of 600, 700, 800 and 900 V. If this results in spectra, check here for instructions on how to select a proper voltage, or check the calibration report for this sensor.

No data is coming in

Power supply

  • Check the power supply. Does it provide a valid voltage (any voltage between 9V and 18V will do for all spectrometers in the default configuration)
  • Is the power supply capable of supplying enough current?
    • An allowed current of 1A or more is recommended.
  • Is there no current limit?
    • Some power supplies show the current in a display. Typical currents should be between 0.1 and 0.3 A.
    • If the current is 0 A, the sensor is not drawing power. If the current is much more, there may be a short. In both cases there is a hardware issue.
  • In case of a battery, make sure it is not drained. Drained batteries may show a good voltage on a multimeter when not loaded. When a detector is connected the voltage may be lower.

Computer configuration

  • Power the sensor and connect it to a computer
  • Open a command prompt (DOS box) and type "ping 192.168.2.100", "ping 192.168.2.101" or "ping 192.168.2.150", depending on the hardware.
    • If there are 4 replies, this means there is a connection between the software and the hardware. Cables, power etc. are not likely to be failing.
  • Make sure the network adapter is configured properly
    • Open the network connections dialog in Windows
    • Right click the wired adapter and select Properties
    • Select Internet Protocol Version 4 (TCP/IP4v), and click the Properties button
    • Select Use the following IP address and type "192.168.2.1" as the IP address and "255.255.255.0" as the subnet mask
    • Close the Properties dialog to apply the new settings
  • Check if the network connections under Windows shows if there is a connection on the wired adapter. Unplug the cable, the status should now show as "cable unplugged".
  • Check if there is a wireless network adapter active in the same IP range (192.168.2.*). If so, change the settings or disable it.
  • Check the firewall settings
    • The (Windows) firewall may block communication between software and hardware. With mDOS systems, it is often possible to find the sensor, but connecting to it is not possible.
    • Open the "Allow an app through Windows Firewall" dialog
    • Click "Change settings"
    • Check if SODL is in the list (make sure to check the file location is correct, SODL can be installed on multiple locations)
    • If it is not in the list, click "Allow another app".
    • Make sure all three check-boxes are checked.

SODL configuration

For each hardware configuration, the software (SODL or MASS) must be configured properly. This means the correct sensor needs to be installed. The configuration files below will configure the software automatically with basic sensors and viewers.

Detector voltage

The detector voltage is an important setting. For each hardware configuration, it can be found on the sensor's settings page. Instructions on settings the detector voltage can be found here. The calibration reports for the sensor list the voltage used during calibration.

Configuration of sensors and viewers

Configuring the software can be done from the device manager, which can be opened by clicking the Device manager button on the settings page. The device manager is not visible for normal users of the software. The button can be enabled by opening the file %LOCALAPPDATA%\SODL\main.ini and adding a line "device_manager.enabled=true" in the [Common] section. Restarting the software is required. After making changes, the device manager can be hidden from the software or by editing the main.ini file.

Cables general

There are different cables available. Information on the cables, including the pin-out can be found on the cable documentation page.

  • Check quality of the connectors
    • Check for corrosion on the pins
    • Check for broken or loose pins
    • Check the cable to see if there is any visible damage to the cable
    • Optional: Unscrew the connectors and check if all wires are still attached. With soldered connections inside heat shrink tubes, pull gently on the wires to see if the connection is not broken.
    • Measure voltage coming out of the cable
      • Check the cable documentation for a pin-out
      • Most cables include a voltage protection circuit. For these cables, the outgoing voltage should be identical to the input voltage, but only when the input voltage is within the specified range.
      • Measure the connectivity of the ground and data wires of the cables using a multimeter.
      • Most cables include a voltage protection circuit. For these cables, there is no connection between the voltage in and voltage out wires.

Inside the sensor

Note that the warranty on the sensor is void when opened without prior approval from Medusa.

General instructions for opening a sensor

  • Remove the 4 threaded inserts from the housing.
  • Remove the cap carefully: there is cabling on the inside. The cap can be removed by pushing the cap up from different sides in small steps.
  • Be careful not to damage the O-ring. Damaged O-rings need to be replaced.
  • Check wiring on the inside of the cap, are there any broken wires on the connectors.
    • Especially soldered wires (Lumberg connectors) may break under stress.
  • Remove the scintillation crystal from the housing
    • Disconnect the PCB connector which connects the end cap or end cap electronics to the electronics on the scintillation detector.
    • Remove the aluminum locking ring. It is locked with M3 locking nuts, these can be removed with a 5.5mm socket wrench. An extender is useful here.
      • Make sure all nuts and rings are recovered.
    • Hold the housing upside down and slowly let the detector slide out (making use of gravity).
  • Putting the scintillation detector back into the housing
    • Carefully place the detector back on the threaded rods. This can be done by extending the rods connected to the rods in the housing using threaded spacers.
    • Place the locking ring with the conical side downwards over the threaded rods and replace the nuts. Add all nuts to the rods before tightening the nuts.
      • Some locking rings do not have conical screw holes. In this case, the rods need to be aligned accurately or else the locking ring won't fit over the rods.
    • Do not fasten the nuts too tightly, there must be some slack in the foam. This can be checked by pushing the locking ring down with the socket wrench, there must be some movement.
    • Check the O-ring for damage or dirt. Clean it in case of dirt, replace it when damaged.
    • Remove any dirt from the inside of the housing before replacing the cap.
    • Put a thin layer of silicon grease (Molykote 111 is used by Medusa) on the O-ring. This helps to seal the detector and protect the O-ring.
    • Put the cap back on the housing. Be careful not to damage the edge of the housing when doing so. Make sure the O-ring stays in the groove before pushing the cap down.
    • Replace the threaded inserts
      • Use locking fluid (loctite blue is used by Medusa)
      • Do not apply force onto the inserts, they can easily damage the carbon fibre of the housing.

MCA527 base type detectors

  • The sensor includes a base with both a USB and an ethernet interface.
  • Issues seen with this sensor type:
    • The MCA527 base is no longer attached to the scintillation detector
    • The ethernet port has broken off
    • The MCA527 base sensors are powered with power over ethernet (PoE). For this Medusa supplies PoE injector units.
      • Check the connectors on the housing for wear or damage
        • The Lumberg connectors are not locked in the housing. When the locking nut on the inside has come loose, the connectors can rotate. If this is the case, the wiring on the inside may become damaged.
          • The Lumberg connectors can be tightened with a special wrench. Locking nuts can be fastened with locking fluid (blue loctite for example). In some cases, metal glue has been applied between connector, locking ring and housing.
      • Open the box by removing the 4 screws.
      • Check the wiring on the inside.
        • Pin-out can be found here
      • Check if all wires are still in place and looking good. Wires with heatshrink tube can be checked by gently pulling on the wires. When the soldered connection is broken, they will come off.
      • Measure the voltage coming in
      • Is the green light on the DC/DC converter active?
      • Measure voltage going out, it should be approximately 48V.
      • When replacing the lid, check the sealing ring and make sure there is no dirt on the sealing.
    • Open the sensor(see above for instructions)
    • Check if the base is still firmly attached to the scintillation crystal.
      • If not, remove it from the detector, remove the old tape, push it back onto the detector and replace the tape. Duct tape works very well.
    • Remove the Ethernet cable going into the base. This cable is has an ethernet connector, which is the commonly used network connector.
    • Put the multimeter in continuity mode and check the data wires from ethernet connector to ethernet connector.
      • Pin-out can be found here.
      • All data wires (green, orange, green/white and orange/white) should be connected from the ethernet connector going into the base all the way to the ethernet connector going into the PC.
    • Power the PoE injector unit and measure the voltage on the ethernet connector going into the base. This should be 48V.
    • Bypass data by using an off-the-shelf ethernet cable and connecting the PC directly to the base. If this results in a working connection, the problem is somewhere in the data lines, either one of the cables, the connectors or the wiring in the PoE injector unit.
    • Bypass power by using an off-the-shelf micro USB cable and power the base directly over USB (using either a power pack, wall socket converter or the PC). If this works, power is a problem, either one of the cables, connectors or wiring in the PoE injector unit.

mMCA v1 type detectors

  • Open a web browser and go to the IP address of the sensor (http://192.168.2.101 by default). A screen showing a login should be visible.
    • If you see this page, there is a connection between computer and sensor. Logging in is not required.
  • Open the sensor(see above for instructions)
  • These sensors have 2 PCB boards directly on top of the scintillation detector.
    • Be careful with the board when it is powered: the high voltage can be up to 1000 volt. There is no danger to people, as the maximum current is very low, but these voltages can easily damage the electronics.
    • The upper board is an Ethernet and power board. It provides an ethernet link and manages power.
      • Measure voltage before the DC/DC converter
      • Measure voltage after the DC/DC converter
    • The lower board (closer to the scintillation detector) is a Medusa Carrier Board. It includes the multi channel analyzer (MCA), pre amplifier and HV module.
      • The amplifier board and the MCA are stacked onto the carrier board. Make sure these are still properly installed. If not, carefully push them down.
      • Do not try to remove the stacked boards.
      • Three wires go from the Medusa carrier board to the detector
        • Black: Ground
        • Red: High voltage
        • Yellow: Signal
      • The high voltage can be measured, but only with a multimeter capable of reading these voltages. Typically, a multimeter can only read voltages up to 600V, but check your multimeter! When the sensor can be connected to using SODL, set the high voltage to a voltage within the range of the multimeter, for example 500 V when the multimeter can handle 600 V.

mDOS sensors

  • Check the LED lights that are embedded in the front cap. Description of the LEDs can be found under section 4.1 on the mDOS getting started page.  During normal operation the LEDs indicate:
    • Top left, color red, status=power, should be solid.
    • Top right, color red or yellow, status=ethernet cable connected, should be solid when a ethernet cable is connected to a computer.
    • Bottom left, color green, status=SCN, will blink every time a spectrum is measured.
    • Bottom right, color green, status=AUX, will blink every time an auxiliary measurement is collected.
  • Open a web browser and go to the web interface of the sensor, by default it can be found at http://192.168.2.150:8000.
    • If the sensor is connected to a network instead of peer to peer to the computer, the Medusa detector finder software can be used to search for the correct IP address.
    • If you see the web interface, there is a connection between computer and sensor.
  • Open the sensor(see above for instructions)
    • These sensors contains 3 PCB boards.
      • A stack of 2 can be found inside the end cap. Not much servicing can be done on these boards.
        • Do not try to remove these boards. The connector is soldered directly to the PCB and heat paste is applied to conduct heat between the boards. Improper re-installation may result in (future) damage.
      • The PCBs in the end cap connect to the Medusa Carrier Board, which includes the multi channel analyzer (MCA), pre amplifier and HV module.
        • The amplifier board and the MCA are stacked onto the carrier board. Make sure these are still properly installed. If not, carefully push them down.
        • Do not try to remove the stacked boards.
        • Three wires go from the Medusa carrier board to the detector
          • Black: Ground
          • Red: High voltage
          • Yellow: Signal
        • The high voltage can be measured, but only with a multimeter capable of reading these voltages. Typically, a multimeter can only read voltages up to 600V, but check your multimeter! When the sensor can be connected to using SODL, set the high voltage to a voltage within the range of the multimeter, for example 500 V when the multimeter can handle 600 V.

Data analisys issues

Corrupt MDL files

  • A stream read error in Gamman may be caused by a corrupt file. To locate the file, try to load the project in batches.
    • An MDL file may become corrupted while copying the file. if the USB stick or similar is removed before the file write action was completed (this can be delayed in Windows), the resulting file may be corrupt. This often shows by a big section of the file being filled with 0x00 only. The solution is to recopy the file(s) and select "remove hardware" from the system tray before removing the USB stick.
    • MASS/SODL crashing may also cause a file to become corrupted. The file write action may not be complete, which also results in an error when Gamman reads the file. The readable section can be extracted using the 'MDL stripper'.
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