Akai GXC-750

Fig. 23
2. PLAYBACK LEVEL ADJUSTMENT
()
(2)
(3)
(4)
(5)
(Refer to Figs. 21 and 22)
Connect a High Sensitivity V.T.V.M. to the
line output of the GXC-75D.
Set machine to forward playback mode.
Set volume controls to maximum (10 position).
Playback a 333 Hz “O” VU recorded test tape
and adjust semi-fixed resistors VR1 500 QB
(left channel) and VRIb 500 QB (right channel)
of Pre-Amp. P.C. Board (CP-5002) to obtain a
High Sensitivity V.T.V.M. indication of 0 dB
(0.775V).
Next, set machine to reverse playback mode
and obtain balance between FWD and REV
playback modes. The High Sensitivity V.T.V.M.
indication at reverse playback mode must be
within a +2 dB range in relation to forward
playback mode.
RECORDING LEVEL ADJUSTMENT
()
(2)
(3)
(4)
(5)
(6)
(7)
(Refer to Figs. 21 and 22)
Connect an Audio Frequency Oscillator to the
line input and a High Sensitivity V.T.V.M. to
the line output of the GXC-75D.
Set Input Selector to LINE position.
Set Tape Selector to LOW NOISE position
and load a blank low noise cassette tape.
Set Volume Controls (located on top panel)
VR3 10 kA (left channel) and VR4 (right
channel) as well as Recording Level Controls
VRI1 (left channel) and VR2 (right channel)
to maximum (10 position).
Set the GXC-75D to recording mode and
supply a 1,000 Hz sine wave signal to the line
input from the Audio Frequency Oscillator
through an Attenuator.
Adjust Attenuator to obtain a 0 dB (0.775V)
High Sensitivity V.T.V.M. indication.
Record under these conditions.
(8)
(9)
SSSREC./P.B. HEAD
FREQUENCY
COUNTER OR
INPUT
Fig. 24
Playback the tape and check the line output
level. In case it is not “0” dB, adjust semi-fixed
resistors VR2 20 kB (left channel) and VR2b
20 kB (right channel) of Pre-Amp. P.C. Board
(CP-5002) to obtain a “‘0” dB line output level.
Adjust so that when a 1,000 Hz signal record-
ing is played back, the difference in the output
level of a reverse recorded tape is within +2 dB
in relation to a forward recorded tape.
4. FREQUENCY RESPONSE ADJUSTMENT
(1)
(2)
(Refer to Fig. 23)
(Refer to FREQUENCY RESPONSE under
MEASURING METHOD, section III)
Record 1 kHz and 10 kHz sine waves signal
at -20 dB. Playback the tape and adjust
semi-fixed resistors VR1 500 kB (left channel)
and VR2 500 kB (right channel) of Syscon &
OSC. P.C. Board (CP-2002) so that the output
level of these two frequencies are equal.
Re-confirm recording level following frequency
response adjustment.
5. RECORDING BIAS FREQUENCY CHECK
()
(2)
(3)
(Refer to Fig. 24)
Set the GXC-75D to recording mode.
As shown in Fig. 24, connect a Frequency
Counter to the coil terminals of the recording/
playback head and read indication.
There is no way to adjust the recording bias
frequency, but the correct frequency is 6143
kHz.