Trane Tracer MP503 - Page 26

26 CNT-SVX09E-EN
Troubleshooting
Figure 11. Voltage measured across terminals vs. temperature
-40 -20 0 20 40 60 80
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
5.5
-40 -20 0 20 40 60 80 100 120 140 160
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
5.5
Voltage (Vdc) Voltage (Vdc)
Temperature (°F) Temperature (°C)
Note: The correct region is shown in gray. A range of measurements is shown due to the variability of reference voltages the thermistors.
Table 19. Universal input troubleshooting with a binary input
Step Number Action Probable Cause
Step 1
After following the steps in Table 17, p. 25, disconnect the sensor wires from the input terminals.
Use volt me
ter (set to read dc voltage) to measure the voltage across the terminals for the input
you are troubleshooting.
The voltage should be 16.00–18.00 Vdc (refer to Table 22, p. 27). If the voltage is not in that
range
, the MP503 has
a circuit board problem.
Circuit board
problem.
Table 20. Universal input troubleshooting with a 0–20 mA input
Step Number Action Probable Cause
Step 1
After following the steps in Table 17, p. 25, use your meter (set to read dc voltage) to measure
the voltage
across the terminals for the input you are troubleshooting. Verify the voltage falls
on the curve shown in Figure 12, p. 27 for the input current.
If the voltage is not appropriate for the mA reading,
you have a sensor wiring problem.
If the voltage is correct for the mA read
ing, proceed to the next step.
Sensor wiring
proble
m.
Step 2
Disconnect the sensor wires from the input terminals. Use your
meter (s
et to read dc voltage)
to measure the voltage across the terminals for the input you are troubleshooting.
The voltage should be 0.10–0.13 Vdc (refer to Table 22, p. 27). If the voltage is not in that range,
the MP503 has a circuit
board problem.
Circuit board
pr
oble
m.