TEST PROCEDURES
5. Headphone Mute3.3 Adjust the generator's output to 35dBf.
Verify that U301 pin 21 is < 2.5Vdc.
5.1 Select the AUX input.
4. Stereo Separation
5.2 Apply a 500mVrms, 1kHz signal to the
L/R AUX input.4.1 Set the RF generator to 65 dBf, pilot on,
left modulation, 1kHz, 100% (75kHz devia-
5.3 Insert a mini-jack into the headphonetion).
output. The A output should mute.
4.2 Reference a dB meter to left FIXED
FM ALIGNMENT TESTS ANDoutput.
ADJUSTMENTS
4.3 Measure the right FIXED output. It
should be L -25dB.
Unless otherwise noted, set an RF genera-
tor to 98.1MHz, 40dBf, 1kHz, mono modu-Note: If the unit fails this test, perform the
lation, pilot off, 100% (75kHz deviation).following procedure.
1. Change R354 to a 560W , 5%, 1/10.
2. Remove W302.
1. Front End Mixer Coil Adjustment
3. Add R355 (a 1kW , 10%, 1/2 W potenti-
1.1 Adjust the FM front end (TUNER) mixerometer). Adjust R355 for maximum separa-
coil until a maximum DC voltage is mea-tion. This option is listed on note 9 of the
schematic.
sured at U301 pin 25. Adjust the coil until
the voltage comes within +0, -20mV of the
peak voltage.5. FM Sensitivity
5.1 Set the RF generator to 42dBf, L= -R
2. FM Detector Zero Adjust and Distortionmodulation, pilot on.
Adjustment
2.1 Set the RF generator to 65dBf.5.2 Reference a dB meter to the left FIXED
output.
2.2 Adjust T305 until the voltage reads5.3 Measure the noise (with modulation off
0Vdc ? 110mVdc across C317+ (AFC test
point) and C322+ (VREG test point).and pilot on) at the right FIXED output. The
SNR should be > 50dB for the 120V ver-
sion and > 45dB for the 220V version.
2.3 Adjust T304 for minimum distortion. TheNote: If the unit fails this test, the FM front
distortion should be < 0.4%.
end should be replaced.
2.4 Repeat this procedure until optimal
results are obtained.
3. FM Stop Level Adjustment
3.1 Set the RF generator to 31dBf.
3.2 Rotate R334 counterclockwise until the
voltage at U301 pin 21 drops below 2.5Vdc.
Then rotate R334 clockwise until the
voltage goes above 2.5Vdc.
Note: The correct adjustment is at the point
just after the voltage switches high.
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ACEC
