Revox A77

16.
Record Level and calibration
oscillator adjustments
Depress button — 6 dB on T19,
position " INPUT"
T19
1 kHz
T19 Adjust generator to read
VU Meter
— 1 dB
—1 dB on both VU- Meters
"REC CAL" potmeters 0/0
fully ccw, increase generator level,
Monitor selector CD in position " TAPE"
Generator
VU Meter
+10 dB
0 dB "REC.LEVEL" Potmeter 0/0
Switch to record and adjust
"RECORD LEVEL" to read 0 dB
on VU- Meter,
Reduce Generator Level
Generator
—10 dB
Raise record level
VU- Meter
0 dB
"REC.CAL" potmeter 0/0
"REC.LEVEL" Potmeter fully
ccw, turn monitor selector
VU- Meter
0 dB
P 103 r
0 to position " CAL" and
adjust calibration oscillator
17.
Checking the DOLBY
Frequency Response
Reduce T19 generator level
by 20 dB,
Turn DOLBY switch CD to
position " IN"
T19
—20 dB
Frequency response
tolerances
T 19 VTVM
7.5
30-20000 Hz
50-15000 Hz
+ 2/-3 dB
± 1,5 dB
OUTPUT
OUTPUT
3.75
30-16000 Hz
+ 2/-3 dB
OUTPUT
50-10000 Hz
± 1,5 dB
OUTPUT
Level difference Mono- Stereo
10 kHz
<0.5 dB OUTPUT
Attenuation of MPX-filter
18 kHz
— 25 dB OUTPUT
18. Checking the Output Level
T19 generator at 1 kHz
1- 19
1 kHz
Adjust record level to 0 VU
Measure output level ( radio output)
T 19 VTVM
560mV ± 1dB
Radio Output
Level difference Mono- Stereo < 1 dB
19.
Distortion Measurement
Measure 3rd harmonic T19 distortion
7.5 1.5 kHz
+ 6 dB
1.5 %
analyzer
3.75
1.5 kHz
+ 6 dB
2 %
7.5
1.5 kHz
0 VU 0.5 %
3.75
1.5 kHz
0 VU
1 %
Values independent of DOLBY
switch position
4- track 2- track
20. Noise measurement off tape
DOLBY- switch CD
T19
3.75
unweighted —53 dB
weighted/unweighted
position " IN"
weighted
—62 dB —64 dB
7.5 unweighted
weighted
—56 dB
—65 dB
—67 dB
DOLBY- switch (;:;)
position " OUT"
3.75
unweighted
weighted
—52 dB
—53 dB
weighting characteristics as per CCIT
7.5
unweighted
weighted
—55 dB
—56 dB
(values as per ASA A, see additional technical data)
21.
Amplifier noise
(without tape)
weighted/unweighted
Recorder in " PLAY" mode,
all noise readings with reference
to + 6 VU,
Tolerances:
7.5
unweighted
weighted
> 58 dB
> 68 dB
3.75
unweighted
weighted
> 58 dB
> 64 dB
Monitor selector 0 in position " INPUT"
> 75 dB
—
—
22.
Crosstalk rejection MONO
As per S.M. 6.6.5., adjust
trimpot P305, if values differ
between DOLBY IN and DOLBY OUT.
23. Crosstalk rejection STEREO As per S.M. 6.6.6.
24.
Erase efficiency
As per S.M. 6.6.4.
25. Final check
MONO- STEREO switch,
track to track transfer, input
sensitivity, noise voltage, S/N ratio
in pos. " MICRO" (> 45 dB)
mechanical inspection