Akai GXC 65 Service Manual

Page 17

7. AUTOMATIC NOISE REDUCTION AMPLI-
O FIER ADJUSTMENT (GXC-60, GXC~60D only)

1) Connect the measuring instruments as shown in
Fig. 25. .

2) Set the Recording Level Control Volume (VRl,
and VR2 50k A) and Volume Control (VR3, and
VR4 l0k A) to lo" position (maximum).

Note: In case of Model GXC-6D, volume controls
can be at any position.

3) Set the Noise Reduction Switch to OFF position,
and supply a 100 Hz signal to the line input from
the Audio Frequency Oscillator.

4) Set recorder to REC mode, and adjust the atten-
uator to obtain a line output level of 0 dB (VU
Meter indication of 0 VU).

Frequency Sudio A T T
Counter renuency~ . . .
Osc1llator
RIGHT CHANNEL 1%"; 2?";

LEFT CHANNEL CE;- get © $.33 2

_ L. GXC6L5- High Sensitivity
_ . me '16 V.T.V.M.
input output
Fig. 25
VRZB
100KB 7'"

,3
a
,4
. i
i
3
é

Fig. 26

5) Set the Noise Reduction Switch to ON position
and, at this time, adjust Noise Reduction P.C.
Board (CS-5327) semi~fixed resistors (VRZ, and
VR2b 300k B) shown in Fig. 27 so that the line
output level is the same whether the NR Switch
is at OFF or ON position.

6) Set the Noise Reduction Switch to OFF position
and set the oscillator frequency of the Audio F re-
quency Oscillator to 10 kHz. Adjust the attenuator
as outlined in Item 4 above.

7) Set the Noise Reduction Switch to ON position
and, at this time, adjust Noise Reduction P.C.
Board (CS-5327) semi-fixed resistors (VRl, and
VRlb 1k B) shown in Fig. 27 to obtain a line
output level decrease of 2.5 dB.

8) After completing the adjustments through Item 7)
supply a 10 kHz signal to the line input and con-

'flrm that when the Noise Reduction Switch is
turned ON, the line output level is decreased to
-26.4 $0.5 dB as compared to the -20 dB level
when the Noise Reduction Switch is turned OFF.