Cross Talk; Signal-To-Noise Ratio* Linear; Signal-To-Noise Ratio? Weighted; Phase Linearity - Revox B225 Maintenance Instructions Manual

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JL\Fi FI&/OX B225 ! SECTION 4/12*
4.3.5 Cross talk
- Adjust for maximum level with VOLUME + key,
- Reference = CAL TONE 1000 Hz)
- Measure both outputs across a 30 kHz low-pass:
Play track 8 for measuring cross talk R -> L
Play track 4 for measuring cross talk L -> R
- The cross talk attenuation should be at least 90 dB.
4.3.6 Signal-to-noise ratio, linear
- Maximum volume, reference = CAL TONE 1000 Hz.
- Play track 18 and measure the outputs FIXED and
VARIABLE via a 30 kHz low-pass.
- The measured value should be higher than -96 dB,
4.3.7 Signal-to-noise ratio, weighted
- Maximum volume, reference = CAL TONE 1000 H z .
- Play track 18 and measure the outputs FIXED and
VARIABLE via an A filter.
- The measured value should be higher than 100 dB,
4.3.8 Phase linearity
- Connect oscilloscope to one of the outputs.
- Play track 20 and visually assess the square-wave
signals at 100 Hz, 400 H z , 1002 H z , and 5512 H z .
The curve should be shaped symmetrically (see
F i g . 4.17). , .
4.4 Listening test with reference CD (part No. 4 6241)
The reference CD simulates the following errors for
checking the error correction system:
- Information gaps with a length of 400 to 900 pm (tracks
5 through 9)
- Black dots from 300 to 800 micrometers
(tracks 1 * 1 through track 17)
- Simulated fingerprint (tracks 18 and 19)
The simulated defects should not cause any drop-outs
(reproduction g a p s ) . If drop-outs become audible, this
can for example be caused by the following errors:
- IC13 (SAA 7010, demodulator), clock regeneration
w i t h PLL defect.
- H F L an DO detector defective.