8 • Service Manual — COATS Models 950/950 ProRacer/1025/1050/1055
Direct Drive
Did you perform weight
sensor and A - D arm
calibration?
No
Is position accurate?
Perform weight sensor & A - D arm
calibration, see Calibration
Procedures
Check/Replace piezo
sensors. Did this correct
problem?
Return to FUNCTIONAL
CHECKS.
Replace PCB Assembly,
see Replacement
Procedure.
Is weight reading
accurate?
Yes
Yes
Yes
No
No
Yes
No
No
Replace optical encoder.
Check for loose shutter
wheel. Did this correct the
problem?
Yes
Turn the power
switch ON.
Is the power switch set
to the ON position?
No
Yes
See the troubleshooting
procedure,
DISPLAY DOES NOT LIGHT.
Does the display light?
No
Yes
No
Reset the tripped breaker.
Did the breaker trip
again?
Has the 1A breaker for
the fan motor tripped?
Yes
Unplug the machine and disconnect
the fan motor lead from the circuit
breaker and reset the breaker. Plug in
the machine and turn the power switch
ON. Did the circuit breaker trip?
Yes
Is the fan motor
running?
No
Return to FUNCTIONAL
CHECKS..
No
Yes
Replace the circuit breaker,
see Replacement Procedure.
No
Yes
Is there 120VAC between the
terminals marked 0V & 120V
on the transformer?
Replace the transformer see
Replacement Procedure.
No
Yes
Replace the fan motor, see
Replacement Procedure.
Fan Motor Does Not Run (Contactor Model)
Accuracy Problems (Plane Separation)