Bose 3-2-1GS Series II Service Manual page 59

15. AM Stop Level
15.1 Inject a 1080 kHz RF signal at a level
of 57 dBuV emf, 30% modulation at 1 kHz.
15.2 Enter the command T2 into
the computer. This will tune the unit to
1080 kHz, then measures, reports, and
stores to EEPROM the S-meter level. You
should receive an "Smeter xx" response
(where xx is the S-meter level) on the com-
puter screen after inputting this command.
15.3 Apply a 1080 kHz RF signal at a level
of 61 dBuV emf, 30 % modulation, 1 kHz.
15.4 Tune the console to 1000 kHz. Press
the seek up >> button on the IR remote
control. Verify that the console stops at
1080 kHz.
15.5 Apply a 1080 kHz RF signal at a level
of 51 dBuV emf, 30 % modulation, 1 kHz.
15.6 Tune the console to 1000 kHz. Press
the seek up >> button on the IR remote
control. Verify that the console does not stop
at 1080 kHz.
FM Tuner Tests
Note: For all FM measurements and adjust-
ments, the RF signal is to be connected from
the signal generator to J2001 via a 50 to 75
Ohm impedance matching network. Ensure
the signal generator is configured a 50 Ohm
output impedance, if necessary. The input
levels stated below are to be as read at the
input of J2001.
FM Adjustments
On the console front panel, switch the
source to FM.
16. FM IF Centering Adjustment
16.1 Inject a 98.1 MHz, 1 kHz mono modula-
tion, pilot OFF, 75 kHz deviation RF signal at
a level of 43 dBuV emf into J2001.
TEST PROCEDURES
59
16.4 Enter the command "T7" into the
computer. The tuner micro will tune the
radio, perform the IF Offset processing, and
write the proper offset to EEPROM. You will
receive a response of "IF Offset: x", where x
is (-1, 0, 1) representing an IF offset of (-25,
0, 25) kHz.
17. FM Distortion Measurement/
Adjustment
17.1 Inject a 98.1 MHz, 1 kHz mono modula-
tion, pilot OFF, 75 kHz deviation RF signal
at a level of 58 dBuV emf into J2001.
17.2 Enter the command TS1A8,0 into the
computer. This will tune the unit to the
appropriate frequency. You will get an "OK"
response from the console.7
17.3 Measure the distortion plus noise
(THD+N) at the console test cable audio
output jacks. If it is less than or equal to
0.60%, verify that the audio level is between
520 to 1050 mVrms. If these are not the
measurements you have, proceed to step
18.4.
17.4 If the THD+N is greater than 0.65%, or
the audio level is not between 520 to 1050
mVrms, adjust T2001 for minimum distor-
tion. Verify that the distortion level is now
less than or equal to 0.60% and that the
audio level is between 520 to 1050 mVrms.
18. FM Sensitivity
18.1 Inject a 98.1 MHz, 1 kHz mono mod-
ulation, pilot OFF, 75 kHz deviation RF
signal at a level of 13 dBuV emf into J2001.
18.2 Measure the THD+N at the audio
output jacks. It should be less than or equal
to 3.0%.
19. FM Stereo Separation
19.1 Inject a 98.1 MHz RF signal set to
1 kHz left only modulation with 10% pilot
modulation and 75 kHz total deviation at a
level 58 dBuV emf into J2001.