Fluid Components International MT86_MT86HT Manual Troubleshooting - Manual (Page 8)

FLUID COMPONENTS INTL CHAPTER 5 - TROUBLESHOOTING
Models MT86, MT86HT 5 - 8 Doc. No. 003162 Rev. F
Warning: Only qualified personnel should test or repair the instrument. The operator assumes all
responsibilities for safe practices while trouble shooting. Damage due to negligence or lack of
technician skill is not covered by the warranty.
Note: If field repair is attempted, replacement parts must be of the same part, type and number.
Calibration Verification Procedure (Using Decade Boxes)
Note: ALL MT86 flowmeters have 1000 ohm RTD sensing points.
ALL MT86HT flowmeters (high temperature flow elements) have 100 ohm RTD sensing points.
Determine which MT86 model type is present and use the ohm value that corresponds to the model
type.
Verify each sensing point one at a time. Select the manual operation mode of the flow transmitter by closing switch
SW1-3. When the flowmeter is in the manual mode, the flow transmitter monitors only the sensing point that the
head-select switch SW2 selects.
Refer to the Delta "R" table for:
1. Delta "R" value in ohms
2. Vdc across 250 ohms
3. Milliamp output signal values
4. Raw signal (un-linearized)
5. 0-10 Vdc analog output signal
6. Display flow rate reading (in customer units) for each signal
Apply the recorded Delta "R" input values to the selected input terminal on the input board. Having the correct data
sheet for the correct input terminal is important.
Procedure
If an FC81 Field Calibrator is used, then go to the verification with a field calibrator procedure.
1. Turn OFF the power to the instrument. Disconnect the flow element cable from the input board terminal
block TS1.
2. Connect two decade boxes or one decade box and a fixed resistor to terminal block TS1 (or TS2 as applicable)
on the input board as shown in the diagram of Figure 5-4.
3. Connect the positive lead of the DMM to the jumper J8 or to test point TP13 located at the bottom of the control
board. Connect the negative lead to the signal ground TP5(-). This readout is the analog signal, 0-10 Vdc, that
is before the span and zero activation circuitry.
4. Close switch SW1-3 that puts the flow transmitter in the manual mode; this enables the head-select switch SW2
to select and monitor one sensing point.
5. Verify that switch SW4 near the bottom of the control board is in the OP (OPerate) position.
6. Set the head-select switch SW2 to position number one; this selects the terminal block TS1 input where the
decade boxes are connected.
7. Set the decade box for the reference sensing point to 1000.00 ohms (100.00 ohms for HT).
8. Refer to the Delta "R" Data Sheet and set the decade box for the active sensing point to 1000.00 ohms (100.00
ohms for HT) plus the recorded Delta "R" resistance value for each sensing point that is designated by SN - #.