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Model 764 Differential Pressure Transmitter Section 4
Troubleshooting
!
WARNING: Except for cleaning the DPU and replacement of O-rings, fas-
teners,andconnectorassemblies,noeldrepairorcomponentreplace-
ment on the Model 764 transmitter is authorized. Unauthorized repairs
voidanycerticationtoqualicationreportsfordesignbasisevent
performance.
Table 4.3—Troubleshooting
Problem Possible Source Probable Cause Corrective Action
No Output Power Source Blown fuse, faulty
component
Replace fuse, repair power
supply
Transmission
Cable
Loose terminal con-
nection
Tighten terminal connection;
locate and replace broken
wire
Receiver (or load) Blown fuse, faulty
component
Replace fuse; repair or
replace receiver or load
Transmitter Loose terminal,
reversed power
connection, faulty
component
Tighten terminal, reverse
power connection, return to
factory for repair
Transmitter
"zeros" but
cannot get
full output
Power Source Low voltage Repair power source
Load Resistance Resistance too high Replace load resistance or
repair as required
Transmission
Cable
Resistance or length
of cable in excess of
specications
Measure cable loop
resistance and bring within
specications
Electronic Module Loss of gain Return to factory for repair
Range Selector Wrong connection or
terminal resistance
increased
Check circuit and operating
procedure for range selector;
clean and tighten terminal
connections
Strain Gage Beam Physical damage Return to factory for repair
Pressure Line Loose tting, broken
tube or valve
Determine source by closing
valves and monitoring for
pressure decay
Out of
Calibration
Electronic Component shifted Return to factory for repair
Erratic
Operation
Terminal
Connections
Loose or dirty Tighten and/or clean as
required
Electronic
Component
Intermittent Check connector assembly
- these are eld replaceable
as a complete assembly only,
any other repair requires fac-
tory service
Strain Gages Physical damage Return to factory for repair
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