Chapter 6. Faults And Troubleshooting; Introduction; Major Alarm And Minor Alarm; Both Speed Sensors Failed - Woodward 723PLUS Technical Manual

Manual 26482
Faults and Troubleshooting
This chapter covers the major and minor alarms, CPU OK LED, POWER OK
LED, FAILED SPD SENSOR #1 LED, FAILED SPD SENSOR #2 LED, LED #3,
LED #4, and the most common problems and their causes. The possible causes
of the alarms or faults and common problems will be covered as well as some
brief troubleshooting.
The faults or conditions that cause an activation of the major or minor alarm
relays are selectable in Configure mode. As shipped, none of the alarms are
selected. The selection of which faults or conditions activate the alarm relays is
up to the operator. The major and minor alarm selection options are identical.
See the description of operation in Chapter 3 for the different selections.
Both speed sensors faulted at the same time will cause the 723PLUS to go to the
minimum fuel position. The speed sensor faults are latching faults (latching
means the fault/alarm condition remains in effect even if the problem disappears,
until the control is reset—see Alarm/Fault Resets below). Intermittent problems
with the speed sensors may cause the speed sensor faults to latch during normal
operation and trigger the actuator driver to go to the minimum fuel position.
Therefore, both speed sensors do not have to fail at the same time to cause
shutdown (actuator driver to the minimum fuel position). As long as one speed
sensor is functioning, the engine may still run properly with the 723PLUS control
even though it is indicating that one of the speed sensors has failed.
The CPU watchdog fault is caused by a CPU failure. A CPU failure will cause the
hardware watchdog monitor to time out. When the watchdog times out, the green
CPU OK LED will turn off and the hardware I/O lock will be activated. The I/O
lock will de-energize all discrete outputs (and all analog outputs will go to zero
current). The hand held programmer may or may not work depending on the type
of CPU failure. The CPU failure can be caused by several things including a
failed CPU, corrupt memory, intermittent input power supply, or a bad or
incorrectly installed program. Generally, if a CPU watchdog fault occurs, the
723PLUS control will need to be replaced.
If the power supply fails, the POWER OK LED will not illuminate. The failed
power supply can be either an internal or external power supply problem. One
cause can be no voltage or improper voltage applied to terminal 1 & 2 (blown
fuse, open wire, etc.). If the proper voltage is applied to terminals 1 & 2, and the
POWER SUPPLY OK LED is still not illuminated, replace the 723PLUS control.
Woodward
Chapter 6.

Introduction

Major Alarm and Minor Alarm

Both Speed Sensors Failed

CPU Watchdog Fault

POWER SUPPLY OK LED

723PLUS Digital Marine Control
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