Union Switch & Signal DIGITAIR 6695 Operation and maintenance manual

MAINTENANCE NOTICE
September, 1998 MN-98-007
MN-98-007
645 Russell Street
Batesburg, SC 29006
MAINTENANCE NOTICE
DIGITAIR® End-of-Train
SBU Model 6695 End Unit
CDU Model 6696 Front Unit
EOT HOTD/Repeater Model 6680
Transceiver Module Replacement
September, 1998
© 1998, Union Switch & Signal Inc.
Printed in USA
UNION SWITCH & SIGNAL
An Ansaldo Signal Company

MAINTENANCE NOTICE
September, 1998 MN-98-007
DIGITAIR®
SBU Model 6695, CDU Model 6696, EOT Repeater Model 6680
Transceiver Module Replacement
REASON FOR REPLACEMENT
US&S is now supplying a synthesized radio
transceiver module for the DIGITAIR® End-
of-Train product line. This product line
includes the SBU Model 6695 End Unit,
CDU Model 6696 Front Unit, EOT HOTD
6680, and EOT Repeater Model 6680.
In the past, these models incorporated a
crystal-controlled transceiver (US&S P/N:
N24600004) which is no longer supplied by
US&S. These products are now shipped
with a new synthesized transceiver module
(US&S P/N: N24600007).
When equipment maintenance requires the
replacement of an existing crystal-controlled
transceiver module installed in one of these
products, a Synthesized Transceiver Kit can
be ordered from US&S under part number
X24600011. This kit includes the following
parts:
1. Synthesized Transceiver Module
2. Metal Shim
3. New FCC/IC Certification Label
4. Quantity 2 Screws (6-32 X 1/2 Pan-Head)
REPLACEMENT PROCEDURE
The new synthesized transceiver module is
fully fit and function compatible with the
SBU Model 6695 End Unit. The metal shim
(item 2) and the screws (item 4) are
required when installing the new transceiver
into the CDU Model 6696, CIU HOTD 6680,
or EOT Repeater Model 6680.
This equipment contains static
sensitive components. Always
work at a grounded workstation
and observe proper ESD handling
practices, otherwise, equipment
damage may result.
Installation into the SBU Model 6695
1. Turn OFF power to the SBU by removing
its batteries.
2. Remove the existing crystal-controlled
transceiver from the SBU by following the
instructions in US&S Service Manual
6497 (aluminum case SBU) or SM 7066
(composite case SBU).
3. Replace with the new synthesized
transceiver module using the existing
fasteners.
4. Per the Service Manuals, adjust the
trimpots on the SBU processor board.
These are trimpot R62 to set RF transmit
power, R50 to set TX deviation, and R43
to set the RX audio level. Refer to the
Operational Test Charts in the manuals.
The new synthesized transceiver does
not require any adjustments for RF
transmitter or receiver center frequency,
however, the transmitter carrier should be
checked to ensure that it is within
specification (+/- 675 Hz). Ensure that
the trimpots are re-locked using Glyptol
(or equivalent) when the adjustments are
complete.
5. Reassemble the SBU as described in the
Service Manuals.
CAUTION

MAINTENANCE NOTICE
September, 1998 MN-98-007
6. IMPORTANT: Adhere the FCC/IC
Certification Label (item 3) over the
corresponding area on the external SBU
nameplate.
7. Installation of the new transceiver into the
SBU does not require the use of the
metal shim (item 2) or the 2 screws (item
4). These can be disposed of, or kept for
use in the CDU or Repeater (if needed).
Installation into the CDU Model 6696 or
EOT HOTD/Repeater Model 6680
1. Disconnect power to the CDU or
Repeater.
2. Remove the existing crystal-controlled
transceiver from the CDU or Repeater by
removing (or opening) the lid and
following the instructions in US&S
Service Manual SM 7064 (CDU Model
6696), or SM 7068 (Repeater Model
6680).
This basically involves removing the 2
screws securing the transceiver bracket
at the rear of the CDU or on the back of
the Repeater and then unplugging the
bracket/transceiver assembly from the
mating DB-15 connector.
3. Unplug the BNC coax antenna cable
connector from the transceiver.
4. Remove the two locknuts securing the
transceiver module to the bracket and
remove the transceiver from the bracket.
5. Install the new synthesized transceiver
module into the bracket and secure it
using the two locknuts.
6. Mount the transceiver/bracket assembly
back onto the rear of the CDU or to the
Repeater case, as follows:
a) Place the metal shim (item 2) between
the transceiver/bracket assembly and the
surface to which it is being mounted
taking care to align the holes. The shim
serves to align the transceiver’s DB-15
connector with the mating DB-15
connector.
b) Use the 2 longer screws supplied with the
kit (item 4) to secure the bracket. Apply
threadlocker to the screws prior to
tightening.
7. Plug the BNC coax antenna cable back
into the mating BNC connector on the
transceiver.
8. In the case of the CDU, plug the Rear
Panel Assembly back into the Base
Assembly per the instructions in SM
7064.
9. Adjust the trimpots in the CDU or
Repeater to set the RF output power and
Tx deviation as specified in the Service
Manuals. Ensure that the trimpots are
relocked using Glyptol (or equivalent)
when the adjustments are complete.
10.Fasten the lid back onto the CDU or
Repeater.
11.IMPORTANT: Adhere the FCC/IC
Certification Label (item 3) over the
corresponding area on the external CDU
or Repeater nameplate.
For additional technical information about
End-of-Train equipment or ordering parts,
contact US&S Customer Service or the
R.A.I.L. Team at 1-800-652-7276 or via
Internet e-mail at: [email protected]