Rotel RT-961, Technical Manual

Page: 7 / 14

Tuner Adjustment Method
FM Section
* Necessary measurement equipment
RDS/STEREO Multiplexer, FM/AM Signal Generator, Audio Analyzer, Oscilloscope, Digital Volt Meter (DVM)
(A) Center adjust
RDS/STEREO Multiplexer Setting
- MODE : MONO - Audio Frequency : 1KHz
FM Signal Generator Setting
- Deviation : 75KHz - Radio Frequency : 98.1MHz - Output Level : 66dB
RT961 Setting
- FM Frequency : 97.9MHz - FM MODE : MONO
1. Turn FM Signal Generator Modulation on
2. Connect DVM (+)(-) terminals to Jumper J7 and J8 and measure the volt.
3. If measured voltage is not adjusted within ±10mV, Make this measured volt '0' by adjusting T04 (FM-DET-A Coil).
: The adjustment should be within ± 10mV
4. After this adjustment, measure THD (Total Harmonic Distortion) with Audio Signal Generator
5. Adjust THD to minimum point with T05 (FM-DET-B Coil). : THD shuold be within 0.5%
(B) Channel Separation adjust
RDS/STEREO Multiplexer Setting
- MODE : STEREO ( ONLY L-CH Signal OUT ) - Audio Frequency : 1KHz
FM Signal Generator Setting
- Deviation : 75KHz - Radio Frequency : 98.1MHz - Output Level : 66dB
RT961 Setting
- FM Frequency : 98.1MHz - FM MODE : STEREO
1. Turn FM Signal Generator Modulation on after modulating only L-CH (or only R-CH) at STEREO Multiplexer.
2. Confirm if ' STEREO' indicator is turned 'ON ' on the display
3. Measure output level via Audio Signal Analyzer and make the level as standard .
4. Turn FM Signal Generator Modulation on after modulating only R-CH (or only L-CH) at STEREO Multiplexer.
5. Measure output level via Audio Signal Analyzer (measure per a dB)
6. If meaured output level is not lower than -40dB, Adjust output level to minimum position with VR03 ( CH-SEPA. ADJ.).
: lower than -40dB
(C) TUNED Level adjust
RDS/STEREO Multiplexer Setting
- MODE : STEREO - Audio Frequency : 1KHz
FM Signal Generator Setting
- Deviation : 75KHz - Radio Frequency : 98.1MHz - Output Level : 26dB
RT961 Setting
- FM Frequency : 98.1MHz - FM MODE : STEREO
1. Turn FM Signal Generator Modulation 'ON' (confirm if output level is 26dB )
2. Change the output level of the Generator from 20dB to 30dB
and Confirm if 'STEREO' & 'TUNED' indicator of the DISPLAY turns on at 26db(±5 dB)
3. If these indicators do not turn on at higher than 26dB(±5dB) or do not turn off at lower than 26(±5dB) ,
Adjust
VR02 ( FM-ADJ )
up to the moment where 'STEREO' & 'TUNED' indicator turns
OFF & ON
at 26dB.
4. Confirm if 'STEREO' & 'TUNED' turns OFF when decreasing the output level slowly from 26dB to 25dB, 24dB ~~~.
(Repeat the above 3. if not OFF in lower than 24dB.)
5. Push RT-961's TUNE UP or DOWN button "long" at Signal Generator Output Level 26dB and start Auto search.
Confirm if search stops at FM Frequency 98.1MHz.
(Examine both of High Freq. -> 98.1MHz search , Low Freq. -> 98.1MHz search)