ClearCom FOR-22 - Page 12

FOR-22 4-WIRE INTERFACE
2-4
AUDIO INPUT LEVEL GREATER THAN +10 DBV
To accommodate input levels greater than +10 dBv on either channel, the
FOR-22 circuit board can be modified to build bridging pads on the primary
side of each channel's input transformer. To build a bridging pad:
1. Find the jumpers labeled R111 and R112 (for channel 1) or R211 and R212
(for channel 2). These jumpers are located under the "Level Detect"
daughterboard; it may be necessary to disassemble the FOR-22 module to
access them. The jumpers look like 1/4 watt resistors with a single black band
(indicating "0 ohms").
2. Replace the jumpers with resistors according to the values shown in Table 1.
3. Install R113 (for channel 1) or R213 (for channel 2) according to the values
shown in Table 1.
Table 1: Resistor Values for Audio Input Bridging Pads
Attenuation
(dBv)
R111/R211
(Ohm)
R112/R212
(Ohm)
R113/R213
(Ohm)
15
20
25
30
470
1k
1k
1.2k
470
1k
1k
1.2k
1.2k
1k
470
470