Akai VS-2EGN

In the cases of tuner reception (when the converter is
not connected to the VIDEO LINE IN) and no signal.
1) With no signal, the E-E picture is a gray picture from
the internal oscillator.
2) When the PB button is depressed, a tuner recep-
tion signal appears regardless of whether or not a pic-
ture is received. *1
3) The condition of 2) continues until the end of load-
ing and in addition for about 2.6 seconds, and then the
TV display is changed to the playback signal picture.
2. VS2-EGN VIDEO CIRCUIT OPERATION
VS-2EGN can perform the recording and playback of
the following signals.
1) Recording and playback of PAL B/G (from Built-in
Tuner to RF OUT)
2) Recording and playback of SECAM B/G (from Built-
in Tuner to RF OUT)
3) Recording and playback of NTSC 3.58M (from Line
in to Line Out)
4) Recording and playback of NTSC 4.43M (from Line
in to Line Out)
5) Playback of SECAM L (to LINE OUT)
Operation of the above five systems will now be des-
cribed. Since the systems differ in the filter characteris-
tics, PAL is mainly described, for the luminance system
section, and for other sections only points differing from
PAL are described.
The chrominance (CHROMA) circuit is described by
dividing it into the following four sections according to
the nature of its signals.
1) PAL B/G and NTSC 4.43 recording and playback
2) SECAM B/G recording and playback
3) NTSC 3.58
4) SECAM L playback
2-1 LUMINANCE (Y) RECORDING AND PLAYBACK
2-1-1 E-E SYSTEM (PLEASE REFER TO THE VIDEO.
SCHEMATIC)
A PAL B/G or SECAM B/G signal from the tuner (de-
modulator) or alternatively a video signal from LINE IN
is terminated at R1 (75), fed to VR-11 (E-E level)
for E-Elevel adjustment and fed to VIDEO AMP IC6
(HA11703) pin O, and output from pin . Quasi
V pulse (VP) is added by TR32 only while in the trick-
play, ie., CUE, REVIEW, and PB/PAUSE. Then, the
signal enters pin and is amplified. Next, the signal is
output from pin , and enters IC5 (HD14053BP) pin
©. Since the video signal is present and 12 VJ line of
the video judge (VJ) circuit in the servo circuit is ‘H’, the
signal is output to pin and then the character signal
is added at TR8 by the output Video on Word (VOW)
from the mi-com of the operation PC board. Now, the
video signal is output to LINE VIDEO OUT via TR2,
and it is fed to the RF converter from the VID terminal
through RL2 (LCB-56) and TR6. In summary, this sig-
nal flow represents the E-E system.
16
‘Service Manual VS-2EGN
*1: In the models other than VS-2EGN, 1) con-
tinues to the part of 2), but in Model EGN, the
PB 12V control line is used to control all play-
back modes. Since the PB 12V is output con-
currently with the depression of the PB but-
ton, the condition 2) appears.
2-1-2 RECORDING SYSTEM
In accordance with the description of the E-E system
in Section 2-1-1, the video signal is applied to IC5 (HD
14053BP) pin , and the character-added video is
applied to pin (2). The signal from pin (1) is output
through ICS output pin (©) at the normal time, ie.,
when pin (©) is ‘H’, and this output signal is fed to the
video head.
However, during the period. when INS LINE is kept ‘H’
by the mi-com of the operation PC board, pin is
kept at ‘L’ via the converter TR29, and the input from
pin @ is output to pin ®. That is, the character-
added video signal is supplied to the video head. ICS pin
@® output is branched to the LPF consisting of FL3,
and the LPF consisting of FL5. The —3 dB point of FL3
is 3.0 MHz, and is 3.3 MHz for FLS.
In the state where a PAL (B/G) or SECAM (B/G) signal
is being recorded, ICS pin is at ‘H’ level. Since pin
is connected to NT-L, only the luminance com-
ponent of the video signal which has passed through the
LPF is output to pi 3.
The output of pin (4) is supplied to IC1 (AN6310) pin
@), and is output to pin @3). During that time, the sig-
nal is subjected to AGC (automatic gain control), and
the deviation (1.0 MHz) of the frequency modulation
circuit in the next-stage is determined by VR8 located
between pins and ©.
The output of the VIDEO AMP circuit (pin @® — pin
) passes through the non-linear emphasis circuit.
The amount of emphasis is determined by TR12 and
TR16 when there is an NTSC signal. Then, the signal
enters pin 48 and is subjected to frequency modu-
lation. Since TR13 connected to pins @®/ @ be-
comes ON in the modes other than NTSC, the FM
carrier frequency is changed.
Dark Clip VR7 is connected to pin (2), while White
Clip VRS is connected to pin (Q). The frequencies of
White Clip, Dark Clip, and Deviation are as follows:
Mode} PAL B/G, SECAM B/G | 4.43, 3.58 NTSC
WHITE CLIP 5.4 MHz 5.0 MHz
PEAK WHITE 4.8 MHz 4.4 MHz
SYNC TIP 3.8 MHz 3.4 MHz
DARK CLIP 3.4 MHz 3.0 MHz