Sony HVR-M15J Service Manual page 152

4. Frequency Characteristic Check
(1) 4CH mode Check
Mode E-E
Signal Audio: 1 kHz, –4 dBs signal
Measurement Point AUDIO OUT terminal (CH-1, 2)
Measuring instrument Audio level meter
Oscilloscope
Specified Value Difference in output level:
Note: 0 dBs = 0.775 Vrms
Switch setting
1) AUDIO MODE (AUDIO SET menu) ......................... FS32K
Checking method:
1) Enter 1 kHz, –4 dBs signal to the AUDIO IN terminal (CH-1).
2) Measure the output of AUDIO OUT terminal (CH-1) at this
time, and assume it to be "a" (dBs).
3) Enter 20 Hz, –4 dBs signal to the AUDIO IN terminal (CH-1).
4) Measure the output of AUDIO OUT terminal (CH-1) at this
time, and assume it to be "b" (dBs).
5) Check with the oscilloscope that no clip is found in the output
waveform.
6) Enter 14 kHz, –4 dBs signal to the AUDIO IN terminal (CH-1).
7) Measure the output of AUDIO OUT terminal (CH-1) at this
time, and assume it to be "c" (dBs).
8) Check with the oscilloscope that no clip is found in the output
waveform.
9) Calculate the difference A (dB) between output levels "b" (dBs)
and "a" (dBs) to check that it satisfies the specified value.
A (dB) = b (dBs) – a (dBs)
10) Calculate the difference B (dB) between output levels "c" (dBs)
and "a" (dBs) to check that it satisfies the specified value.
B (dB) = c (dBs) – a (dBs)
11) For the CH-2, make a checking in the same manner.
HVR-M15J/M15U/M15N/M15E/M15P/M15C
20 Hz, –4 dBs signal
14 kHz, –4 dBs signal
AUDIO IN terminal (CH-1, 2)
A = –2 to 0 dB
B = –1.5 to +1.5 dB
(2) 2CH mode Check
Mode
Signal
Measurement Point
Measuring instrument
Specified Value
Note: 0 dBs = 0.775 Vrms
Switch setting
1) AUDIO MODE (AUDIO SET menu) ......................... FS32K
Checking method:
1) AUDIO MODE (AUDIO SET menu) ................. FS48K
Checking method:
1) Enter 1 kHz, –4 dBs signal to the AUDIO IN terminal (CH-1).
2) Measure the output of AUDIO OUT terminal (CH-1) at this
time, and assume it to be "a" (dBs).
3) Enter 20 kHz, –4 dBs signal to the AUDIO IN terminal (CH-1).
4) Measure the output of AUDIO OUT terminal (CH-1) at this
time, and assume it to be "b" (dBs).
5) Check with the oscilloscope that no clip is found in the output
waveform.
6) Calculate the difference A (dB) between output levels "b" (dBs)
and "a" (dBs) to check that it satisfies the specified value.
A (dB) = b (dBs) – a (dBs)
7) For the CH-2, make a checking in the same manner.
6-58
E-E
Audio: 1 kHz, –4 dBs signal
20 kHz, –4 dBs signal
AUDIO IN terminal (CH-1, 2)
AUDIO OUT terminal (CH-1, 2)
Audio level meter
Oscilloscope
Difference in output level:
A = –1.5 to +1.5 dB