ZETRON 640 DAPT XTRA, Installation And Repair Manual, Page: 98 / 210

Adjustment Procedures
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Test Equipment
The following equipment is required to adjust the trunk card levels:
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buttset
•
digital voltmeter (DVM)
•
miniature flat head screwdriver
•
small Phillips head screwdriver
•
touch-tone phone
Notes: The trunk card adjustments are very important. They affect background noise
immunity when recording voice prompts, speech silence compression, DTMF key
decoding, VOX disconnect features (if used), and modem communications.
Follow each procedure carefully.
FROM TEL Adjustment
In general, leave FROM TEL in the factory adjusted position. If there is too much silence
deletion, then turn the pot clockwise. If there is not enough silence deletion, then turn the pot
counterclockwise.
Follow the steps below to perform the factory adjustment for FROM TEL:
q
1. Remove the top cover of the Model 640 chassis (if not already done).
q 2. Remove the plate covering the trunk adjustment pots.
q 3. Create a new Class of Service in the Model 640 database as follows:
•
Select 1 - Subscriber Phone Numbers from the main menu.
•
Select 2 - Class of Service from the Subscriber Phone Numbers menu.
•
Enter N to create a New record.
•
Fill in the record as shown in Figure 49.