Akai GX-2800D-SS User Manual

REC, HEAD
FREQUENCY
COUNTER
3. RECORDING LEVEL ADJUSTMENT
1) Connect an Audio Frequency Oscillator to the
line input terminals through an attenuator and
connect a high sensitivity V.T.V.M. to the line
output terminals.
2) Depress the ‘7-1/2 ips” Tape Speed Selector
Switch and set the Stereo Selector to “4-CH”
position. 7
3) Set line recording level controls to maximum
and load a Scotch #111 blank tape.
4) Set the Monitor Switch to TAPE position and
set the tape deck to recording mode. Supply a
1,000 Hz signal from the Audio Frequency Oscil-
lator, and adjust the attenuator to obtain a
V.T.V.M. indication of 4 dB (1.228V).
5) Set the Monitor Switch to SOURCE position,
and adjust REC. Amp. P.C. Board recording level
adjustment semi-fixed resistor VR1 (5. kB) and
VR1b (5 kB) shown in Fig. 18 (VR1 front/rear
left channel; VR1b front/rear ‘right channel) to
obtain a line output level of 4 dB on each channel.
. RECORDING BIAS FREQUENCY MEAS-
URING METHOD AND ADJUSTMENT
MEASURING METHOD:
Method I
1) As shown in Fig. 25, ‘install a 1 to 2 resistor
in series with the recording head and connect
both of these terminals (a) and (b) to the vertical
input of the oscilloscope and set deck to record-
ing mode.
2) Supply a sine wave to the horizontal input of
the oscilloscope from the Audio Frequency Oscil-
lator.
3) Vary the oscillation frequency of the audio fre-
quency oscillator until the oscilloscope waveform
displays a circular or linear pattern.
4) If the oscillation frequency indication is within
100 to 110 kHz when a circular or linear pattern
is displayed, the recording bias frequency is cor-
rect.
FROM OSC,
AUDIO
FREQUENCY
o OSCILLATOR
Fig. 25
Method 2
1) Connect a Frequency Counter to both terminals
(a) and (b) as shown in Fig, 25. Set deck to
recording mode and take a frequency counter
reading.
2) If the frequency counter indication at this time
is within 100 to 110 kHz, the recording bias
frequency is correct.
ADJUSTMENT
The recording bias. frequency can be adjusted by
changing the value of OSC. P.C. Board condenser
C4 (4500P/500 WV) shown in Fig, 26.
. RECORDING BIAS VOLTAGE ADJUST-
MENT (Frequency Response Adjustment)
1) Connect the various Measuring instruments in
the same way as outlined in “Recording Level
Adjustment” procedure,
2) Follow Recording Level Adjustment procedure
through Item 4 and set the attenuator to —20 dB.
3) Under these conditions, adjust OSC. P.C. Board
recording bias voltage adjustment trimmer con-
densers TC1 (front left), TC2 (front right), TC3
(rear right), and TC4 (rear left) 70P shown in Fig.
26 to obtain an equally flat frequency response
at 1,000 Hz. and 10,000 Hz.
4) After frequency response adjustment is complet-
ed, the recording bias voltage is within 2 to 5V
ALC,
5) Proper erase voltage is within 65 to 70V A.C.
NOTE: Frequency response will vary depending
upon the tape being used. (As a general
tule, AKAI 100F (Fuji F) tape is used.
19

Akai GX-2800D-SS Specifications

General

Brand	Akai
Model	GX-2800D-SS
Category	Tape Deck
Language	English