VCP-015-02-x Installation & Operation Manual
Document # 540228, Rev A, 05/2003
Page 12 of 18
8.0 Instructions for Continued Airworthiness
8.1 Unit
Maintenance
•
Ensure the unit is not exposed to excessive heat, moisture, splashing
liquids, dusty areas, direct sunlight, or angled/inclined installations.
Any of these conditions may damage the unit.
•
Adequate ventilation MUST be maintained; see Section II, Subsection
5.0 for ventilation details.
•
VCP-015-002-x should be periodically cleaned with a standard
commercial VCP cleaning tape. Cleaning steps may vary depending
on the product used; be certain to follow the cleaning tape directions of
the product you use.
•
Never
force the videocassette into the receiving slot.
Never
place
foreign objects into the VCP unit.
8.2 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.
