47
TROUBLESHOOTING GUIDE
This guide is written for a technician familiar with the operation and programming
described previously in this manual. 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 888-248-1988 for technical support.
1. No Power
2. No Display
3. DC Power Fault
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. Thepower
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
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