3-36 L90 LINE CURRENT DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL
PILOT CHANNEL COMMUNICATIONS CHAPTER 3: INSTALLATION
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Figure 3-35: Typical pin interconnection between two G.703 interfaces
3.4.3.2 G.703 selection switch procedures
1. With the power to the relay off, remove the G.703 module (7R or 7S) as follows. Record the original location of the
module to help ensure that the same or replacement module is inserted into the correct slot.
2. Simultaneously pull the ejector/inserter clips located at the top and at the bottom of each module in order to release
the module for removal. (For more information on accessing modules, see the Maintenance chapter.)
3. Remove the module cover screw.
4. Remove the top cover by sliding it towards the rear and then lift it upwards.
5. Set the timing selection switches (channels 1 and 2) to the required timing modes.
6. Replace the top cover and the cover screw.
7. Re-insert the G.703 module. Take care to ensure that the correct module type is inserted into the correct slot position.
The ejector/inserter clips located at the top and bottom of each module must be in the disengaged position as the
module is inserted smoothly into the slot. Once the clips have cleared the raised edge of the chassis, engage the clips
simultaneously. When the clips have locked into position, the module is inserted fully.
Pin nomenclature differs from one manufacturer to another. It is not uncommon to see pinouts numbered TxA, TxB,
RxA, and RxB. In such cases, assume that “A” is equivalent to “+” and “B” is equivalent to “–.”
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