Ring Communications CB901EX - Manual (Page 16)

CB901EX Operations Manual March 2011
The wire dimensions for stations located further from the central must be increased accordingly.
However, independent local DC power supplies can be used for distant stations. No reference wiring
between local and central power supplies is required.
Important Note: If a number of stations are powered from a common/parallel DC power pair,
voltage fluctuations can result in incidental crosstalk. Therefore it is essential that a separate power pair
is always used for each station.
INSTALLATION OF CENTRAL EXCHANGE
Each basic cardrack and subscriber cardrack consists of two main parts: a metal backplate and a
front cardrack (which secures to the backplate with 2 screws) that swivels outward, giving access
behind the motherboard during maintenance.
Check for signs of physical damage when unpacking the central. In particular check the long
contact-pins on the rear of the motherboards PCB979, PCB980 for possible distortion that may cause
short-circuiting.
MOUNTING THE CARD RACK BACKPLATE
Four holes in the backplate are provided for mounting on a wall or 19" rack. The position of the
cardracks should allow for easy access of incoming station cables.
Mount the backplate, as follows:
a. Drill holes corresponding to the backplate in the wall.
b. Mount the backplate (see note).
NOTE: The four screws required for wall mounting the central unit are not provided. Be certain
that the screws used can support the central unit.
When using two cardracks for a central unit, two 20-pair flat cables (NMF6002) are supplied with
DP 980 Cardrack to connect the two units together. The cables have a fixed length, thus limiting the
distance between the cardracks to approximately 10-12 cm (4-4,5 inches). (See Fig. 1.6, 1.7). The top
pin of Cable no. 1 in each pin row will not be connected.
The backplate is now ready for station wiring.
Page 16 of 77
Ring-Master