Airport 828HC, Instruction Manual

Page: 26 / 49

16
© Airport Lighting Company
Problem Likely Cause(s) Steps to Fix
All DCMU LEDs are
flashing at the
same time
- The internal DCMU
power supply card is
shorting.
- The internal DCMU
power supply card
capacitors discharged.
- If all of the DCMU LEDs are flashing
on and off simultaneously, it is likely
that there is a component drawing
more p ower from the DCMU than it’s
designed to provide. To determine if
this is true, complete the following
steps:
- Turn off power to the CCR. Wait for
power to completely discharge by
monitoring the LEDs. Once they are
all off, power is no longer present.
- Unplug the serial cable connected to
the left side of the DCMU, and the
firing card. The thumbscrews need to
be loosened before removal.
- Reapply power to the CCR. If the issue
persists, replace the DCMU if a spare
is available.
- If the issue is resolved with the serial
cable disconnected, replace the serial
cable, firing card, and megger card (if
installed) one at a time to determine
the cause of the problem.