Telex MCE325 manual Ifb A, Four-WireA Input to Left Headphone, Four-WireB input to Right Headphone

IFB A

1Move the J4 jumper to short pins 1 and 2 (IFB A assigned to channel 3).

2Remove the signal from PROGRAM B input, and connect it to the PROGRAM A input. Set the signal generator to 0 dBu, 1 kHz.

3Check the output level across intercom channel 3. It should be –9.8 dBu ±2 dBu.

4Turn on the CH 3 TALK and MIC ON buttons. The channel 3 output should drop at least 45 dB from the reference level in step 3.

5Turn off the CH 3 TALK and MIC ON buttons.

6Ground the Key 3 input (short J22 pin 7 to pin 10). The channel 3 output should drop at least 45 dB from the reference level in step 3.

7Remove the Key 3 ground.

8Move the J4 jumper to short pins 2 and 3.

Level and Frequency Response Check, Four-Wire Input to Headphone

Four-Wire A Input to Left Headphone

1Set all front panel buttons to off. Set all volume controls to minimum.

2Remove the signal generator from the Program A input, and connect it to the Four-Wire A input (AUXILIARY connector J22, pins 8 and 21). Set the generator to 0 dBu, 1 kHz.

3Move jumper J19 to short pins 3 & 4 (Four-Wire A input always on).

4Set the CH 1-3 volume control to measure 0 dBu at the left headphone output. (The control should be at about the 2 o’clock position.)

5Set the signal generator to 0 dBu, 100 Hz. The left headphone output should be –0.9 dBu ±2 dBu.

6Set the signal generator to 0 dBu, 10 kHz. The left headphone output should be –4.7 dBu ±2 dBu.

7Move jumper J19 to short pins 2 & 3 (Four-Wire A input off).

Four-Wire B input to Right Headphone

1Remove the signal from the Four-Wire A input, and connect it to the Four-Wire B input (J22, pins 9 & 22).

2Move jumper J20 to short pins 3 & 4 (Four-Wire B input always on).

3Set the CH 2-4 volume control to measure 0 dBu at the right headphone output. (The control should be at about the 2 o’clock position.)

4Set the signal generator to 0 dBu, 100 Hz. The right headphone output should be –0.9 dBu ±2 dBu.

5Set the signal generator to 0 dBu, 10 kHz. The right headphone output should be –4.7 dBu ±2 dBu.

6Move jumper J20 to short pins 2 &3 (Four-Wire B input off).

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