Fluid Components International MT86_MT86HT Manual Troubleshooting - Manual (Page 4)

FLUID COMPONENTS INTL CHAPTER 5 - TROUBLESHOOTING
Models MT86, MT86HT 5 - 4 Doc. No. 003162 Rev. F
Troubleshooting Process - Voltage Measurements
Verify the use of the correct power source. Verify the power source is on and that the wiring matches the wiring
diagram in Figure 2-2 of Chapter 2.
If the flow element resistance and wiring check out, recheck the power supply; the fuse and the AC and DC voltages.
The power supply should be suspect when there seems to be multiple failures in the flowmeter.
Perform the following voltage checks with power applied to the flowmeter. The flowmeter should be put in normal
operating conditions. Make all measurements with the use of a DMM that has a differential (non-grounded) input.
Note: The flow element sensing point voltage readings are for 1000 ohm RTDs.
Power Supply Source Voltages
Measure the power source at the power supply terminal block TS1 to be sure the correct power is applied.
Check the power supply voltages, using the test points provided. See Table 5-3 and Figure 5-2 for the proper operating
voltages. If the voltage checks are correct, the power supply is functioning properly.
Table 5-3. Power Supply Voltages - Power Supply Board
*Measurement points are not available on some power supplies.
If operating power is at terminal block TS1 and the test points do not have power, check fuse F1 on the power supply
board.
Remove power and unplug the power supply from the control board. Apply power to the power supply and re-measure
the voltages as shown in Table 5-4. If the voltage is still missing, then remove and replace the power supply.
Make the following measurements at the control board terminal strip. See Figure 5-3 and Table 5-4 for the
measurements.
Table 5-4. Power Supply Voltages - Control Board
POSITIVE LEAD (+) NEGATIVE LEAD (-) MEASURED VALUE
TP1 TP4 28 Vdc ±1 Vdc
TP2 TP4 15 Vdc ±.6 Vdc
TP3 TP4 5 Vdc ±.3 Vdc
TP5 TP4 -5 Vdc ±.3 Vdc
TP6 TP4 -15 Vdc ±.6 Vdc
VC6 VGND -26.43 Vdc ±1 Vdc*
VC1 VGND 43.4 Vdc ±2 Vdc*
Positive Lead (+) Negative Lead (-) Measured Value
TP15 TP16 10 Vdc ±.02 Vdc
RN1 PIN 3 TP16 5 Vdc ±.04 Vdc
U5 PIN 7 TP16 -10 Vdc ±.06 Vdc