AEC OFC Series - Manual (Page 29)

Extrusion Control & Extruder Monitor Units Chapter 6: Troubleshooting 28
Chapter 6: Troubleshooting
6-1 Introduction
The utmost in safety precautions should be observed at all times when working on or around
the machine and the electrical components. All normal trouble-shooting must be
accomplished with the power off, line fuses removed, and with the machine tagged as out of
service.
The use of good quality test equipment cannot be over-emphasized when troubleshooting is
indicated. Use a good ammeter that can measure at least twice the AC and DC current that
can be encountered for the machine. Be sure that the voltmeter has at least minimum
impedance of 5,000 OHMS-per-volt on AC and 20,000 OHMS-per-volt on DC scales.
Popular combination meters, VOM and VTVM can be selected to provide the necessary
functions.
Before making haphazard substitutions and repairs when defective electrical components are
malfunctioning, we recommend that you check the associated circuitry and assemblies for
other defective devices. It is common to replace the obviously damaged component without
actually locating the real cause of the trouble. Such hasty substitutions will only destroy the
new component. Refer to wiring diagrams and schematics.
Locating mechanical problems, should they occur, is relatively straightforward. When
necessary, refer to the parts catalog section.
Problem Possible cause Corrective action
Fuse may have blown. Check fuse.
If the unit fails to operate.
? Check main power.
?
Check power line for
fluctuations.
If unit stops intermittently.
?
Check the extruder screw
speed pick-up proximity
switch.
?
Check weigh hopper for
binding or overfill.
?
Check proximity sensor
mounting and adjustments.
?
Check wiring to panel and
sensors.
?
Check motorized pot for
binding (if equipped).
?
Check load cell A/D in
diagnostics to ensure that the
load cell is not damaged and is
linear. Consult factory. If the unit is inaccurate.
?
Check to see that the additive
pellets are feeding consistently
out of the weigh hopper and
not bridging occasionally in
the hopper discharge throat.