Detcon DM-200 - Manual (Page 28)

Model DM-200
DM-200 Instruction Manual Rev. 2.0 Page 24 of 40
5. Trouble Shooting Guide
"Missing Sensor" Message
Probable Cause: ISM not being registered by UTM.
1. Reinstall ISM after waiting 10 seconds.
2. Re-power UniTox sensor.
Upscale reading (for > 30 minutes) after ISM connection
Probable Cause: Biased ISM type re-stabilizing.
1. Wait 8 hours minimum.
2. Use Battery Back-up Module to prevent this condition.
"Comm Error" Message
Probable Causes: Faulty wiring/connection, UTM or ISM microprocessor failure.
1. Re-Install ISM.
2. Swap ISM and UTM with another functional pair to determine if ISM or UTM is the problem.
No LCD or 4-20 mA signal activity with power applied
Probable Causes: Blown input fuse, Insufficient Operating Voltage, Mis-wired connection.
1. Check/Replace Fuse.
2. Check for correct polarity and verify Operating voltage at the UTM input terminals.
3. Check status of external field wire I.S. Barrier.
4. Replace UTM with functional UTM.
Noise Spikes or Oscillation on the 4~20mA signal
1. Contact Detcon to report incidence.
2. Install 150µF capacitor across the terminating load resistor at the controller (i.e. install between DC
common and mA input).
LCD not Easily Readable
1. Adjust contrast pot (see section 14).
Erratic Sensor Behavior – False/Fault Alarms
Probable Causes: Wet/Intermittent terminals, RFI Interference, Bad Electrochemical Sensor, Target or Cross-
interfering Gases being detected.
1. Check that ISM collar and splashguard adapter are firmly seated and terminals are not wet.
2. RFI- Use shielded cabling.
3. Re-calibrate sensor and make sure it calibrates successfully and Sensor Life is acceptable.
4. Make sure alarms are not being caused by real gas clouds or cross-interfering gases.
"Span Cal Fault" Message