Yamaha IM8-32, Service Manual

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111
IM8-40/IM8-32/IM8-24
2-8 PEAK, 0 dB and -20 dB LED light-up level
In the state described in section 2-1, PEAK, 0 dB and -20 dB LED of each channel shall light up when a signal within the range
shown in the Table 2-8-1 is fed to the input.
Table 2-8-1 [dBu]
INPUT -20 dB LED (Green) 0 dB LED (Yellow) PEAK LED (Red)
CH1–40/32/24 -80 ± 3 -60 ± 2 -43 ± 2
ST CH1–4
*1
-54 ± 3 -34 ± 2 -17 ± 2
*1 Insert jacks to both the L and R and input a signal one side at a time.
Check that the PEAK, 0 dB and -20 dB LEDs of the GROUP OUT 1 – 8, AUX SEND 1 – 8 and MONO OUT light up when a
signal within the range shown in the Table 2-8-2 is fed to the input.
Table 2-8-2 [dBu]
-20 dB LED (Green) 0 dB LED (Yellow) PEAK LED (Red)
-16 ± 3 +4 ± 2 +17 ± 2
2-9 Meter LED lighting check
Set the MONITOR control to the Nominal Position.
Check that the PEAK LED of the METER lights up when the ST, MONITOR OUT level r17.5 ± 2 dBu. Check that the “0”
LED of the METER lights up when the ST, MONITOR OUT level r4.0 ± 2 dBu.
Check that the “-30” LED of the METER lights up when the ST, MONITOR OUT level reaches -25.0 ± 3 dBu.
Operate the ST MASTER fader and check that LEDs light up in order from “-30” to “PEAK”. (Check the MONITOR OUT by
operating the ST MASTER fader with the ST AFL switch turned ON.)
2-10 Distortion
In the signal routes of the Table 2-2-1 to 2-2-12 indicated with ($), ($1), ($2) and ($3), set the VR and Fader of INPUT and
MASTER to the Nominal Position and set the GAIN to the position speci
fi ed in the Table. Then, feed 20 Hz and 1 kHz signal
respectively and check that the distortion is 0.1 % or less when the output signal at each OUTPUT is +14 dBu (except PHONES
OUT). Then, feed 20 kHz signal and check that the distortion is 0.15 % or less when the output signal at each OUTPUT is +14
dBu (except PHONES OUT).
In case of the INPUT other than the MONO or ST CH INPUT, feed 20 Hz, 1 kHz and 20 kHz signal respectively and check that
the distortion is 0.1 % or less when the output signal at each OUTPUT is +14 dBu.
At the PHONES OUT (L/R), feed 20 Hz, 1 kHz and 20 kHz signal respectively with the PHONES control set to the 12 o’clock
position and check that the distortion is 0.2 % or less when the output signal at each OUTPUT is +3 dBu.
* ($1): Check the GROUP 1 and GROUP 3 when the signal is fed to CH 1 and check only the GROUP 1 when the signal is fed
to CH 2 or other channels.
* ($2): Check CH 1 only.
* ($3): Check AUX 1 only.
* Only when measuring the AUX RETURN or 2TR IN, set the AUX RETURN control, 2TR IN control and STEREO L/R con-
trol to MAX.
2-11 Maximum Output (@1 kHz)
In the state described in section 2-1, the distortion at 1 kHz should be 1 % or less when the output level is +24 dBu at the ST L/R
OUT, MONO OUT and AUX 1 – 8 OUT, and +20 dBu at the GROUP 1 – 8 OUT, MATRIX OUT and MONITOR OUT. The
distortion at 1 kHz shall be 1 % or less when the output level is +7.5 dBu at the PHONES (L/R). In measuring the ST L/R OUT or
GROUP 1 – 8 OUT, fully turn the PAN or BAL control to L or R.
2-12 Equivalent Input Noise
In the state described in section 2-1, shunt the CH INPUT MIC terminal with 150 Ω , turn the ST ASSIGN and CH ON switches on
and check that the noise level at the ST OUT is -128 dBu or less.