GOODRICH Stormscope Series II, Installation Manual, Page: 57 / 65

WX-950
Installation Manual
4-12
Rev. C
4.6 TROUBLESHOOTING ELECTRICAL NOISE
The noise (interference) source can be isolated in two ways: by switching off one system at a time
(preferably at the circuit breaker); or by running a system which cannot be switched off through all its
operational modes. When the proper WX-PA response or system self-test response is restored, the offending
system has been identified.
Systems that are common noise sources include:
•
Alternators or generators
•
Autopilot systems (especially trim servos and amplifiers)
•
Pulse systems (DME, transponder)
•
Strobe lights or beacons
•
Air conditioners or heater blowers
•
Fluorescent light systems
•
Windshield heat
Electrical noise can be coupled into the WX-950 system by several avenues:
•
Radiation into the Antenna.
•
Grounding problems due to poor airframe bonding.
•
Faulty component interference source.
•
Excessive ripple on the A+ line to the Processor.
The following procedures are intended to facilitate the resolution of suspected noise problems.
1. Access the service menu (refer to paragraph 4.4) and run the noise monitor (refer to paragraph 4.4.4)
to reproduce the problem on the ground.
If a problem cannot be reproduced on the ground, schedule a flight test for further
troubleshooting.
2. To check for interference radiated into the antenna or cable:
a. Use a WX-SM Skinmapper. The Skinmapper checks for radiated noise only.
b. To isolate noise to antenna or cable, replace the antenna with the WX-900 connector pod (P/N
78-8060-6001-4). Repeat noise check. If the noise goes away, the problem is noise radiated into
the antenna.
3. Isolate the aircraft system that generates the noise.
4. Repair, replace, or relocate the offending source, or relocate the Stormscope antenna or cable, if
necessary.
5. Check potential noise sources close to the system (cables, boxes, components).
6. It may be necessary to relocate the antenna or offending device (e.g., cables, communications antenna).
7. All grounds must conform to cabling procedures detailed in chapter 2 (Installation - refer to
paragraphs 2.7 and 2.8). The interference source must be properly grounded. It may be necessary to
relocate the WX-950 system airframe grounds, or airframe grounds on the interference source.
8. Powering the processor from an isolated DC power source may identify excessive ripple on the A+ line
as an interference source. It may be necessary to install an in-line filter on the processor, or on the
interference source.
If the noise cannot be isolated to an aircraft system, contact our Customer Service Department at
1-800-453-0288 or 1-616-949-6600 for advice and assistance.