Chapter 15 Troubleshooting
90 CNT-SVN01C-EN
Figure 53. Voltage measured across terminals vs. temperature
Figure Note:
The correct region is shown in gray. A range of measurements is shown due to the variability of reference voltages
and thermistors.
Table 26. Universal input troubleshooting with a thermistor input
Step number Action Probable cause
Step 1 Set the multi-meter to read dc voltage. Measure the voltage across the termi-
nals for the input you are troubleshooting. Verify the voltage you measured
falls into the gray area of the curve in Figure 53 for the current temperature.
If you do not see the voltage reading appropriate for the current temperature,
you have a sensor wiring problem.
If you do see the correct voltage for the current temperature, proceed to the
next step.
Sensor wiring
problem
Step 2 Disconnect the sensor wires from the input terminals. Set the multi-meter to
read dc voltage. Measure the voltage across the terminals for the input you are
troubleshooting.
The voltage should be 4.75–5.25 Vdc (see Table 30 on page 92). If you do not
see a reading in that range, the Tracer MP581 has a circuit board problem.
Circuit board
problem
Table 27. Universal input troubleshooting with a binary input
Step number Action Probable cause
Step 1 Disconnect the sensor wires from the input terminals. Set the meter to read dc
voltage. Measure the voltage across the terminals for the input you are trouble-
shooting.
The voltage should be 16.00–18.00 Vdc (see Table 30 on page 92). If you do not
see a reading in that range, the Tracer MP581 has a circuit board problem.
Circuit board
problem
Temperature (
o
F)
Voltage (Vdc)
Temperature (
o
C)
Voltage (Vdc)
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