Telex MCE325 manual Initial Configuration, Keying Output Test

4Measure the ripple.

Vripple = 140 mVp-p

5Measure the regulated DC voltage at U26 pin 2. (There should be no ripple.)

VU26-2= 13.85 ±0.3 VDC

6Measure the mid-voltage source at U17 pin 7. VU17-7= 6.93 ±0.3 VDC

7Measure the +5 V source at the output of U27 pin 2. VU27-2= 5.0 ±0.3 VDC

Initial Configuration

1Set all internal jumpers and DIP switches as follows:

DIP Switches: Set all DIP switches, except DS3, to the default settings listed in Table 2.1. Set DS3 to on. (This places the MCE325 in four-channel mode. Refer to Figure 1.11 for names of buttons in standard four-channel mode.)

Jumpers: Set all jumpers, except J24, to the default settings listed in Table 2.2. Set J24 to the balanced mic position (pins 1 and 2 shorted).

2Connect a 200-ohm termination resistor across each of the four intercom channels:

CH 1: J8 pins 1 and 2

CH 2: J8 pins 1 and 3

CH 3: J10 pins 1 and 2

CH 4: J10 pins 1 and 3

3Set all front panel buttons to off.

4Set all volume controls to minimum.

Keying Output Test

1Connect two 47 k ohm resistors: one from the key 1 output (J22 pin 6) to the +14 VDC supply; and one from the key 2 output (J22 pin 19) to the +14 VDC supply.

NOTE The cathode of D22 serves as a convenient connection point for the +14 VDC supply. (Refer to the AS6245 drawing in Section 6 for the location of D22.) The key 1 and key 2 outputs require external pull-up resistors. The key 3 and key 4 outputs have internal pull-up resistors (RP2B and RP2D respectively) and do not require external pull-ups.

Figure 4.1 Auxiliary connector, J22.

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