TROUBLESHOOTING GUIDE
(from MCD Manual-version date 2017)

This guide is written for a technician familiar with the operation and programming described  in the manual previously provided. All procedures in this can be performed with simple hand tools and a volt-ohm meter. If at any time, additional assistance is required, call SenTech Corporation at Direct: 317-596-1988 or Toll Free:888-248-1988 for technical support.

1. No Power  

 
 
2. No Display
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

 



3. DC Power Fault 
 
 
 
 
 
 
 
 
 
 
 
 
 
 












4. Pneumatics Failure 



 
























 5. Failure to Detect a Leak or 
       Suspected Low Sensitivity 
 






















 6. System Alarms when no 
       Leak is Found 

a) Check the fuse and replace if failed.
b) Check incoming AC Power at TB1-2 and TB1-3.

a) Verify AC Power.
b) Check for red lights on the control board. The power light in the upper left corner of the control board should be lit. Shortly after initial power up, the red light labeled “RYL6” should light (closest to the hinges). This signifies that the reference air valve has been energized. During normal operation, this light will be off when in Auto Sample mode, and on when in Auto Zero mode. If any alarms exist, one two or three lights will light corresponding to “RLY1”, “RLY2” and “RLY3” (Low alarm, Main alarm and High alarm respectively).

 
 If no power lights are lit, there is a DC power fault. If the power lights are lit, but the “RLY6” does not light, or the controller is not periodically lighting the “RLY6” light, the control board has a fault.
 
a) If there is AC power to the monitor, but there are no lights lit on the control board, check the control board DC voltage: Identify the power resistor R53 in the lower left corner of the board. Measure the DC voltage between the right side of the resistor and chassis ground on the lower left corner of the board. The DC voltage should be between 20.4 and 24.0 vdc. Identify the 12 volt voltage regulator VR2 in the lower left corner of the board. Measure the DC voltage between the LEFT PIN of the voltage regulator and chassis ground on the lower left corner of the board. The DC voltage should be between 11.8 vdc and 12.2 vdc.
 
If either dc voltage measurement is out of spec, there is a power fault in the control board, or a wiring short causing a power fault in the control board. Turn off the monitor and remove one connector at a time from the control board. Apply power between each step. If the dc voltages remain out of spec, the control board has failed.

a) Check that the diaphragm pump is operating and replace if it has failed.
 
b) Check that the tubing inside the monitor has not come loose from any fitting, or become kinked at any point.
 
c) Check that the orifice or tube end filter have not become clogged or restricted.
 
d) Check that the tubes connected to the sample air inlet and fresh air inlet have not become clogged or restricted.
 
e) Check that the solenoid valves are switching. Verify that the light labeled “RLY6” is switching on and off. Verify that the red LED’s on turning on an off, according to which area is being sampled. Verify that the voltages on Valve Driver Board, J4 are changing from approximately 24 vdc to approximately 0 vdc, according to which area is being sampled. Temporarily block the air inlet and listen for the diaphragm pump to draw a vacuum. If the pump does not change tone, and is known to work, the valve is not switching.
 
a) Alarm lights are on, but external alarm devices are not actuated. Repeat the “Integration with External Devices” from the Final test portion of the manual.
 
b) Alarm light is not on, but a leak is suspected. Verify that the alarm settings are not set too high.
 
Refer to “Startup and Programming” section of the manual for instructions.
 
c) Repeat the complete procedures described in the “Final Tests” section of the manual.
 
d) Verify that the sample air and fresh air pick up point locations are appropriate in accordance with the “Installation” section of the manual.
 
e) If the monitor does not respond to refrigerant, contact SenTech Corporation technical support.
 
a) Verify that the alarm is not a “Trouble Alarm” as described in Appendix A of the manual.
 
b) Verify that the alarm settings are not set too low. Refer to “Startup and Programming” section of the manual for instructions.
 
c) Inspect the area for the presence of halogenated organic chemicals. Some degreasers and cleaning agents are made of organic chemicals containing chlorine, fluorine or bromine. Such chemicals might cause an alarm.
 
d) Inspect the area for oil leaks. Oil can contain trace amounts of refrigerant, and will likely cause a transient alarm.
 
e) Verify that there truly is no refrigerant leak in the area. This includes all machines and stored refrigerants.
 
If none of the above resolves the problem, the unit has likely failed. Contact SenTech Corporation technical support for assistance. 
 
 
 
  
 

TROUBLESHOOTING GUIDE
(from SNIF 1,2,3 Manual-version date 2017)

This guide is written for a technician familiar with the operation and programming described  in the manual previously provided. All procedures in this can be performed with simple hand tools and a volt-ohm meter. If at any time, additional assistance is required, call SenTech Corporation at Direct: 317-596-1988 or Toll Free:888-248-1988 for technical support.

1. No Power  

 
 

2. No Display
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

 
3. DC Power Fault 
 
 
 
 
 
 
 
 
 
 
 
 
 
 













4. Pneumatics Failure 



 

















 
5. Failure to Detect a Leak or 
      Suspected Low Sensitivity 
 





















 6. System Alarms when no 
       Leak is Found 

a) Check the fuse and replace if failed.
b) Check incoming AC Power at TB1-2 and TB1-3.  

 
a) Verify AC Power.
b) Check for red lights on the control board. Two lights should be lit on the control board. A power light will be lit in the upper left area of the control board. Another light should be lit in the center right area of the board. This will be either the red light labeled “RYL5” or “RLY6”. Following “Optics Warm-up”, the controller will alternate between “RLY6” (fresh air) and “RLY5” (sample air), at approximate two-minute intervals.  
 
 If no power lights are lit, there is a DC power fault. If the power lights are lit, but the neither “RLY5” nor “RLY6” are lit, or the controller is not alternating between them, the control board has a fault. 
 
a) If there is AC power to the monitor, but there are no lights lit on the control board. Measure the DC voltage supplied to the control board. Identify the power connector, P9 and the power resistor, R53 on the lower left corner of the board. Measure the DC voltage between the left side of R53 and chassis ground. This measurement should read between 22vdc and 25vdc.
If there is no DC voltage, turn off the monitor and remove one device at a time from the DC power circuit. The 24 vdc relays can be removed from the relay socket. The control board can be disconnected at the input terminal on the board. The solenoid valves can be disconnected at TB1-6. Note: the power supply must have a load to operate, so each item must be disconnected, then tested and replaced. 
 
b) If there is DC voltage on R53, check the 24 vdc terminals on the alarm relays. Using the wire-list from the previous section, isolate the fault to a wiring problem. 
 
a) Check that the diaphragm pump is operating and replace if it has failed. 
 
b) Check that the tubing inside the monitor has not come loose from any fitting, or become kinked at any point. 
 
c) Check that the orifice or tube end filter have not become clogged or restricted.  
 
d) Check that the tubes connected to the sample air inlet and fresh air inlet have not become clogged or restricted. 
 
e) Check that the solenoid valves are switching. Verify that the lights labeled “RLY5” and “RLY6” are switching on and off. Temporarily block the air inlet and listen for the diaphragm pump to draw a vacuum. If the pump does not change tone, and is known to work, the valve is not switching. 
 
a) Alarm lights are on, but external alarm devices are not actuated. Repeat the “Integration with External Devices” from the Final test portion of this manual. 
 
b) Alarm light is not on, but a leak is suspected.  Verify that the alarm settings are not set too high. Refer to “Startup and Programming” section of this manual for instructions. 
 
c) Repeat the complete procedures described in the “Final Tests” section of this manual. 
 
d) Verify that the sample air and fresh air pick up point locations are appropriate in accordance with the “Installation” section of this manual. 
 
e) If the monitor does not respond to refrigerant, contact SenTech Corporation technical support. 
 
a) Verify that the alarm is not a “Trouble Alarm” as described in Appendix A. 
 
b) Verify that the alarm settings are not set too low. Refer to “Startup and Programming” section of this manual for instructions. 
 
c) Inspect the area for the presence of halogenated organic chemicals. Some degreasers and cleaning agents are made of organic chemicals containing chlorine, fluorine or bromine. Such chemicals might cause an alarm. 
 
d) Inspect the area for oil leaks. Oil can contain trace amounts of refrigerant, and will likely cause a transient alarm.  
 
e) Verify that there truly is no refrigerant leak in the area. This includes all machines and stored refrigerants. 
 
If none of the above resolve the problem, the unit has likely failed. Contact SenTech Corporation technical support for assistance. 
 
 
 
  
 

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