Akai GX-2800D-SS

FRONT RIGHT
FRONT LEFT
OUTPUT SIGNAL
OUTPUT SIGNAL
OSCILLOSCOPE
~FRONT RIGHT
OUTPUT SIGNAL
6. 4-CHANNEL PHASE CHECK
Method A
1) Connect front left signal and front right signal
from the line. output terminal to vertical and
horizontal input terminal of Oscilloscope. (See
Fig. 28)
2) Playback a 250 HZ “0” VU pre-recorded test
tape at 7-1/2 ips.
3) If front left and front right are In-Phase, the
waveform as shown in Fig. 29 will appear on
the oscilloscope screen.
4) If phase is 180° out of phase, a waveform as
shown if Fig. 30 will appear on the oscilloscope
screen.
5) Make the same check on front left/rear left and
rear left/rear right.
6) The line outputs should be In-Phase, if not, Re-
cording/Playback Head needs adjusting.
IN PHASE Fig. 29
Fig. 28 :
OUT-OF PHASE Fig. 30
HIGH
SENSITIVITY
V.T.V.M.
IN PHASE +4dB
OUT-OF PHASE —5dB8 Fig. 31
Method B (See Fig. 31)
1) Playback a 250 Hz “0” VU pre-recorded test
tape at 7-1/2 ips.
2) Connect front left signal and front: right signal
of line output terminals in parallel and connect
this to a high sensitivity V.T.V.M. (Model 161A).
3) If In-Phase, the line output will be about +4 dB.
4) At 180° out of phase, the line output will be
about —5 dB.
5) Make the same check on front left/rear left and
rear left/rear right.
21