Fluid Components International MT86_MT86HT Manual Troubleshooting - Manual (Page 7)

Doc. No. 003162 Rev. F 5 - 7 Models MT86, MT86HT
CHAPTER 5 - TROUBLESHOOTING FLUID COMPONENTS INTL
If a voltage is missing, unplug all the input and output boards. Measure the voltage again to see if the voltage has
returned. If it has returned plug in the boards one at a time until the board is found that is loading the circuit.
Remove and replace the board. If the voltage does not return, replace the control board.
Flow Element Operating Voltages
Close switch SW1-1. All output signals should go to the minimum signal level. Return switch SW1-1 to the open
position after testing. Make the following measurements at the input board terminal strip. See Table 5-5 and
Figure 5-1 for the measurements.
Table 5-5. Input Board Terminal Voltage Check
*The above readings are at 80°F (27°C) and 14.7 PSIA and at no-flow. The readings will vary with temperature and
flow. However, the reference voltages should always match and the active voltages should always match. The active
voltages should be higher than the reference voltages.
Troubleshooting Process - Flow Element Current
To measure the currents put a DMM in series with the desired lead. See Table 5-6 for the measurements.
Table 5-6. Current Measurements
If there are no problems, the flow elements are good. Further trouble shooting must concentrate outside of this area.
Go to the following sections.
Field Calibration Techniques
The flowmeter circuit cards and the flow element can be replaced as separate items. A field calibration is needed
after the replacement of the parts.
Positive Lead Negative Lead Measured Value
(+) (-) MT86 MT86HT
HTR + HTR - 16.5 Vdc 16.5 Vdc ±1%
REF SEN GND SEN 1.10 Vdc 0.275 Vdc*
REF EXC GND SEN 1.10 Vdc 0.275 Vdc*
ACT SEN GND SEN 1.25 Vdc 0.275 Vdc*
ACT EXC GND SEN 1.25 Vdc 0.275 Vdc*
Component
Measured Value (mA DC)
MT86 MT86HT
REF SEN O.OO O.OO
ACT SEN O.OO O.OO
REF EXC 1.OO 2.5O
ACT EXC 1.OO 2.5O
HTR + 75.O ±5% 75.O