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4 APPENDIX
4.1 INTERNAL ACCESS
1.
Remove six screws from the back cover.
2.
Remove the top cover. This provides access to all in-
ternal adjustments.
3.
For option card installation, slide the circuit board out
toward the back to remove it from the bottom cover.
Telex Communications, Inc., Made in U.S.A.
AUX
J4B
J1B
J3B
J2B
2 WIRE SYSTEM
4 WIRE SYSTEM
Figure 9. Location of screws for disassembly
RV202
Figure 10. Locations of internal controls
4.2 MODE DIP SWITCH SETTINGS
S301 contols the operating mode for System B and S302
controls the operating mode for System A. Settings are
summarized in Table 4.
16 User Instructions, SSA-424 Dual Digital Hybrid
AUX
J5 POWER
+5V 3A
+15V 1.6A
-15V 0.3A
J4A
RTN
+5V
+15V
-15V
J1A
J3A
RTN
J2A
4 WIRE SYSTEM
RV201
S301
S302
RV102
RV101
Table 4. Mode DIP Switch Settings
Switch Settings
1
2
3
4
Off
Off
Off
Off Configuration 1, Half / Full Duplex
Mode: Automatically switches between
modes. Useful in situations where there
is high ambient noise. Also useful when
there is acoustic feedback.
On
Off
Off
Off Configuration 2, Switched Full Duplex
Mode (Default Setting): Switches from
half duplex to full duplex 3-9 seconds
after conversation begins on the 4-wire
line. Stays in full duplex mode until
60-90 seconds after conversaton
ceases. This helps to keep the line
quiet during periods of no conversa-
tion, while permitting natural conversa-
tion when people are talking. This is
the preferred operating mode for many
situations, and particularly for fast,
close-coordination, team operations.
On
Off
Off
On Configuration 3, Locked Full Duplex
Mode: Same as configuration 2, but
once a hybrid enters full-duplex mode, it
stays in that mode until power-down.
Off
Off
On
Off Configuration 4, Half / Full Duplex
Mode: Similar to configuration 1, but
with higher sensitivity.
Half-duplex Definition: Only one side of the line can
talk at a time and the other side must wait until the
first side is done talking before responding.
Full-duplex Definition: Both sides of the line can
talk simultaneously.
4.3 LEVEL DISPLAY CALIBRATION
This is a factory preset adjustment and should not re-
quire readjustment.
1.
On the front panel, set the 4W LEVEL REF SEL
controls to -10dB.
2.
Set the 2W CHAN SEL switches to 1.
3.
Input a 1 kHz, -10dBu test signal at J1A (System A)
or J1B (System B). (Pin 1, signal common; pin 2, sig-
nal high).
4.
Adjust RV101 (System A) or RV201 (System B)
while watching the top display (TO4W). All of the
green displays should be lit and no amber displays
should be lit.
5.
Remove the test signal.
Description
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