Service manual

CHANNEL RECEIVER VOTER MODULE (cRVM)
6-6
March 2000
Part No. 001-3139-502
6.8 AUDIO ALIGNMENT
NOTE: This is a pre-installation procedure, intended
for use in a "bench" alignment of an RVM. It is not
intended for alignment of an operational voter
system.
6.8.1 RVM REMOVAL
Remove all external connections to the RVM to
be aligned (i.e. clips from punch blocks or backplane
connectors).
6.8.2 RVM AND CHANNEL SELECTION
On the SMM, select the desired RVM to be
aligned and enable each of the channels.
1. Remove RVM from the Voter shelf and place it into
an Extender Card.
2. Place jumpers on J2, J3, J4 and J6 to enable align-
ment task (see Figure 6-4).
3. Inject 1200 Hz at -20 dB into P1, pins 25/26.
4. Reset RVM.
6.8.3 CHANNEL 1 AUDIO OUTPUT LEVEL
The RVM will be self-aligning Channel 1 to the
on-board reference tone (1200 Hz) generated at FSK
chip U29, pin 8. The self-alignment will take approxi-
mately 5 minutes.
When the self-alignment of U40 is complete its
associated LEDs CR1 and CR2 will start flashing.
1. Connect the transmission test set to TP2 and verify
U40 is -20 dBm ±2 dBm.
2. Connect the transmission test set to P1, pin 21, mea-
sured output should be -25 dBm.
3. If adjustment is necessary, note setting and select
U44 by setting S2 sections 1/3 Off, 2 On.
4. To decrease the audio output level set S2, section 4
"On".
5. To increase the audio output level set S2, section 4
"Off".
6. Adjust the audio output level by pressing S1 repeat-
edly until -25 dBm is measured.
6.8.4 CHANNEL 2 AUDIO OUTPUT LEVEL
Remove the 1200 Hz from P1, pins 25 and 26
and connect 1200 Hz to P1, pins 27 and 28. Remove
the jumper from J6 and place it onto just one of the
pins. The LEDs CR1 and CR2 will turn off and the
RVM will be self-aligning Channel 2 to the on-board
reference 1200 Hz tone. The self-alignment will take
approximately 10 seconds.
When the self-alignment of U41 is complete its
associated LEDs CR3 and CR4 will start flashing.
1. Connect the transmission test set to TP3 and verify
that U41 has been aligned to -20 dBm ±2 dBm.
2. Connect the transmission test set to P1, pin 21.
3. Verify the audio output level measures -25 dBm.
6.8.5 CHANNEL 3 AUDIO OUTPUT LEVEL
Remove the 1200 Hz tone from P1, pins 27 and
28. Connect the 1200 Hz tone to P1, pins 29 and 30.
Remove the jumper from J2 and place it onto just one
of the pins. LEDs CR3 and CR4 will turn off and the
RVM will be self-aligning Channel 3 to the on-board
reference tone. The self-alignment will take approxi-
mately 10 seconds.
When the self-alignment of U42 is complete its
associated LEDs CR5 and CR6 will start flashing.
1. Connect the transmission test set to TP4 and verify
that U42 is -20 dBm ±2 dBm.
2. Connect the transmission test set to P1 pin 21,
measured output should be -25 dBm.