DVD-301-01-x Installation & Operation Manual
Document # 540257, Rev B, 08/2005
Page 29 of 39
5.0
Instructions for Continued Airworthiness
In addition to the cautions and warnings provided in Section 3.3, the following
guidelines and instructions will help ensure proper functionality and performance
from the DVD-301-01-x
5.1
Recommended Cleaning Method
DVD-301-01-x should be cleaned routinely at least once every three
months to ensure proper functionality. Use a standard DVD cleaning disc
(not included with the DVD-301-01-x) and follow the listed directions.
5.2
General Troubleshooting Procedures
•
28 VDC power is applied to the proper pins on the unit. Use a
voltmeter to verify correct level.
•
Reset by removing power from the unit for at least one (1) minute and
reapply power.
•
Recheck all connections to the unit for security and all harness runs for
possible pinching. Recheck all pinouts for application accuracy.
•
Utilizing a voltmeter, oscilloscope, or other voltage instrument, verify
proper input voltage on the data bus pins to check data bus integrity.
Typical measurements are as follows:
A to Ground : 4.0 to 4.5 VDC
B to Ground : 0.1 to 0.2 VDC
If any device is transmitting (i.e., holding bus active), then these typical
measurements would be reversed for the A-to-Ground and B-to-
Ground measurements. This troubleshooting tool can help indicate a
data bus lockup.
If this occurs, remove the data bus from all other
equipment one piece at a time. As each is removed, check the bus
status to see if it is now functioning properly. Once you have removed
the piece or pieces of offending equipment, disconnect power and then
reconnect everything but the suspect component, reapply power and
test the functionality of the unit.
•
The RS-485 data bus is a bi-directional bus that does not have a ‘bus
controller’. The bus uses a differential digital signal that will transmit
only when commands are entered via switch selection or other system
synchronizing commands. The “A” leg of the bus is HI and the “B” leg
LO.
