Akai VS-2EGN

The frequency-modulated Y signal (FMY) from IC1 pin
(©) is directed to pass through the HPF consisting of FL1
(1.4 MHz at —3 dB point) so as to prevent interference
with the low frequency converted CHROMA (mentioned
later). Thereafter, the signal is controlled at VR4 (Y
REC LEVEL), mixed with the low frequency converted
CHROMA, passed through the REC Signal Inter-Board
Connection to the Audio/Pre P.C Board, fed to the PRE
AMP circuit, and supplied to the video head through the
emitter follower (TR10) and the constant current buffer
(TR8/9).
Since TR5 and TR6 are grounded by REC 12V during
recording, a closed circuit of REC current is formed via
R43, and VIDEO data is recorded on the tape.
2-1-3 PB SYSTEM
Since TR4 of the pre-amp circuit goes ON during play-
back, the PB VIDEO signals (FMY + Low Frequency
Converted Chroma) from the video heads 1 and 2 are
1) DROP OUT Pulse Generator (Refer to Fig. 7-8)
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At the time of a drop-out occurs, IC2 pin (0) becomes
‘L’, causing 1C3 (wH741TC) pin G) to become ‘L’.
Since C46 (1uF/S5OV) has only just started to discharge
pin @ does not become ‘L’. That is, the output is ‘L’.
D3 is for operation stop in the E-E mode.
The output of IC2 pin () is fed to the double limiter
circuit in which the signal is divided into two.
First it is directed to the HPF composed of C48, R62,
and C47, amplified at TR7, phase corrected at C39 and
R37, amplified at TR15, and fed to IC4 (TA7060AP)
pin @ . The signal is amplitude-limited at the 1st limit-
et between pin (1) and pin (4), and then applied to the
emitter of TR18.
Secondly, the output of IC2 pin ® is directed to the
LPF (4 MHz at —3 dB point) composed of R80 and
C57, and applied to the base of TR18. At the collector,
this signal appears, mixed with the first signal which is
applied to the emitter.
After being phase-corrected at TR9, L10, and R47, the
‘Service Manual VS-2EGN_
supplied to IC2 (AN6320N) pins@)and(5) After going
through pins 3) /G), PB VIDEO signals of CH-1 and
CH-2 are selected by the Amplifier Switching Pulse
which connects them to pins and ©, after the
overlap portions have been cut off. The outputs from
pins and (9) are mixed on the way to pin a, and
the mixture flows to pin () after going through the
MIX AMP, and then to the video PC board as a PB PRE
OUT through the emitter follower (TR7). On the video
board, the PB signal from the pre-amp is directed
through the HPF (1.4 MHz at —3 dB point) consisting of
C1, 5,6, R10, 11, and L1. Only FMY is extracted there,
fed to the 5.8 MHz peaking circuit composed of L35,
C203, and TR3, subjected to the phase correction at
C15, 16 and L6, fed to pin (3 of IC2 (HA11718) sub-
jected to AGC; and then output from pin () of IC2.
When there is a drop-out, the signal 1H earlier is output
from pin () and supplied to pin (} by DL1 (64 us
delay).
1
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© ‘
Fig. 7-8 DROP OUT Pulse Generator
signal is fed to IC6 (HA11703) pin (4) via the emitter
follower of TR39. After being amplitude-limited and
FM-demodulated on the way from pin) to pin@) the
signal is directed through the respective filters of FL8
(PAL), FL6, 7 (NTSC), and FL9, 10 (SECAM), and fed
to IC7 (HD14066BP) pins, @), Now, if both con-
trol signal lines 3N-H and 3L-H from the servo circuit are
‘L’ (PAL mode), the signal passes from IC7 pin (1) to
pin (), is directed to the non-linear de-emphasis circuit
composed of TR34, L20, C91, D8, and D9, phase cor-
rected at L11 and C102, then fed to IC6 pins @ and
®, and output from pin ©.
PB CHROMA is supplied to pin ® and mixed there.
The output of pin (16) passes through VP ADD of TR32.
17