Telex MCE325 Benutzerhandbuch
4-6
C S I - 2 0 0 U s e r I n s t r u c t i o n s
8
Repeat for channels 2 through 4 by activating the TALK buttons, connecting to the test points
and adjusting the potentiometers as indicated in Table 4.4.
and adjusting the potentiometers as indicated in Table 4.4.
True Sidetone Adjust
1
Configure the DYN MIC HEADSET jack for stereo mode (See Section 3, “MONO”)
2
Set all front panel buttons to off.
3
Connect 51 ohm load resistors across the left headphone output (J2 pins 3 and 4) and right
headphone output (J2 pins 3 and 5).
headphone output (J2 pins 3 and 5).
4
Connect an AC voltmeter across the left headphone output.
5
Remove the signal generator from the mic input, and connect it across intercom channel 1.
Adjust the generator output to –1 dBu (0.69 VAC), 1 kHz.
Adjust the generator output to –1 dBu (0.69 VAC), 1 kHz.
6
Activate the CH 1 TALK button, and adjust the CH 1-3 volume control (R1) until you measure
11.2 dBu (2.82 VAC) across the left headphone output.
11.2 dBu (2.82 VAC) across the left headphone output.
7
Disconnect the signal generator from intercom channel 1. Adjust the generator for minimum
output, and reconnect it across the DYN MIC HEADSET jack mic input (J2 pins 1 & 2).
Readjust the generator output level to –45 dBu, 1 kHz.
output, and reconnect it across the DYN MIC HEADSET jack mic input (J2 pins 1 & 2).
Readjust the generator output level to –45 dBu, 1 kHz.
8
Turn on the MIC ON button.
9
Adjust R37 (sidetone) on the MCE325 main board to obtain 8.7 dBu (2.1 VAC) at the left
headphone output.
headphone output.
Level and Frequency Response Check, Intercom Channel to
Headphone
Headphone
1
Set all front panel buttons to off.
2
Remove the signal generator from the mic input, and reconnect it across intercom channel 1.
3
Adjust the signal generator output to –1 dBu, 1 kHz.
4
Preset the CH 1-3 volume control to the 2 o’clock position.
5
Activate the CH 1 TALK button. The left headphone output level should be 11.2 ±2 dBu (2.2
to 3.6 VAC).
to 3.6 VAC).
6
Adjust the CH 1-3 volume control to measure 11.2 dBu (2.8 VAC) at the left headphone
output. Check for no distortion or clipping in the output.
output. Check for no distortion or clipping in the output.
7
Adjust the signal generator output to –1 dBu, 100 Hz. The left headphone output should read
10.2 dBu ±2 dBu (1.9 to 3.2 VAC)
10.2 dBu ±2 dBu (1.9 to 3.2 VAC)
8
Adjust the signal generator output to –1 dBu, 10 kHz. The left headphone output should read
7.8 dBu ±2 dBu (1.5 to 2.4 VAC).
7.8 dBu ±2 dBu (1.5 to 2.4 VAC).
9
Repeat the test for channels 2 through 4. For channel 3, continue to use the CH 1-3 volume
control and monitor the left headphone output. For channels 2 and 4, use the CH2-4 volume
control and monitor the right headphone output.
control and monitor the left headphone output. For channels 2 and 4, use the CH2-4 volume
control and monitor the right headphone output.
Table 4.4
Channel 1-4 sidetone trimmer adjust.
TALK BUTTON TEST POINT POTENTIOMETER
CH 1
U5 pin 7
R57 (Sidetone 1)
CH 2
U5 pin 1
R73 (Sidetone 2)
CH 3
U7 pin 1
R88 (Sidetone 3)
CH 4
U7 pin 7
R104 (Sidetone 4)