Detcon TP-624C - Manual (Page 22)

Reg40004 Data Hi 00 0 0000 0000
Reg40004 Data Lo 14 20 0001 0100
Reg40005 Data Hi 05 5 0000 0101
Reg40005 Data Lo 50 80 0101 0000
CRC ## #### ####
CRC ## #### ####
Additional Notes:
The calibration LED will light when the transmitter is sending a response to a Master Query.
Communications are 9600 baud, 8 data bits, 1 stop bit, No parity, half duplex 485.
3.12 D
ISPLAY
C
ONTRAST
A
DJUST
Model TP-624C MicroSafe™ sensors feature a 16 character backlit liquid crystal display. Like most LCDs, character
contrast can be affected by viewing angle and temperature. Temperature compensation circuitry included in the
MicroSafe™ design will compensate for this characteristic, however temperature extremes may still cause a shift in
the contrast. Display contrast can be adjusted by the user if necessary. However, changing the contrast requires that
the sensor housing be opened, thus declassif ication of the area is required.
To adjust the display contrast, remove the enclosure cover and use a jewelers screwdriver to turn the contrast adjust screw
located beneath the metallic face plate. The adjustment location is marked “CONTRAST”. See figure 7 for location.
3.13 T ROUBLE S HOOTING G UIDE
SENSOR FAULTS
Open Heater
Verify resistance between black and white wires using ohm-meter with the sensor unplugged and at room tempera-
ture. Heater Film’s normal reading range should be 65-95 ohms. Failure would be an open circuit.
Open Sensor
Verify resistance between blue and yellow wires using ohm-meter with the sensor unplugged and at room tempera-
ture. Sensor Film’s normal reading range should be 5-100 k-ohms. For sensors with an “X” in the serial number, the
normal reading range should be 75 k-ohms to 2 meg-ohms. Failure would be open circuit.
SPAN CALIBRATION FAULTS – (Range, Stability, Zero)
To remove the span calibration fault, you must repeat the calibration process successfully.
Range Fault
1. Check Heater Voltage Setting (should be 5.25 V).
2. Use humidif ier with Distilled Water.
3. Check validity of cal gas using H2S pull tube or other means.
4. Check for obstructions through s/s sinter element (including being wet).
5. Check sensor lot # and report to Detcon .
Zero Fault
Must recover to <10% of range before calibration cycle is complete and returns to normal operation. Use bottled
air if necessary.
Poor calibration Repeatability
1. Check for adequate Sensor Life.
2. Check Heater Voltage Setting (should be 5.25 V).
3. Use humidif ier f illed with Distilled Water.
4. Check validity of cal gas.
5. Check for obstructions through s/s sinter element (including being wet).
Detcon Model TP-624C Hydrogen Sulfide Sensor PG.22