Video Circuit; D/A Level; Ee Y Level; Rec Color (Colour) Level - JVC HR-S3800U Service Manual

3.3 VIDEO CIRCUIT

3.3.1 D/A level

Signal (A1) • Ext. S-input / Ext. input
(A2) • Color bar signal [NTSC]
Mode (B1) • S-VHS
(B2) • EE
Equipment (C) • Oscilloscope
Measuring point (D) • IC501 - pin 19 (V TO OSD)
Adjustment part (F) • VR1201 (D/A LEVEL ADJ)
[2D DIGITAL board]
Specified value (G) • 2.05 ± 0.03 Vp-p (reference value)
(Note)
(1) Observe the VIDEO OUT waveform at the measuring
point (D).
(2) Check the Y level value when the External S-input (Y/C
separated video signal).
(3) Switch the input signal to the External input (compos-
ite video signal), and adjust the adjustment part (F) so
that the Y level becomes the same value observed in
step (2).
Note:
• The specified value (G) is just a reference value to be
obtained when the External S-Video (Y/C separated
video) signal is input. In actual adjustment, set it to the
value observed in step (2).
Fig. 3-3-1a

3.3.2 EE Y level

Signal (A1) • Ext. input
(A2) • Color bar signal [NTSC]
Mode (B) • EE
Equipment (C) • Oscilloscope
Measuring point (D) • Y OUT terminal (75Ø terminated)
EVR mode (F1) • Jig RCU: Code "57"
EVR address (F2) • A:11 (Press remote controller
"1" key twice)
Specified value (G) • 1.00 ± 0.05 Vp-p
Adjustment tool (H) • Jig RCU [PTU94023B]
• Digit-key remote controller
(1) Observe the Y OUT waveform at the measuring point (D).
(2) Set the VCR to the EVR mode by transmitting the code
(F1) from the Jig RCU.
(3) Set the EVR address to (F2) by pressing the button of
the digit-key remote controller.
(4) Adjust with the channel buttons (+, –) on the VCR (or on
the remote controller) so that the Y level of the Y OUT
waveform becomes the specified value (G).
(5) Release the EVR mode of the VCR by transmitting the
code (F1) from the Jig RCU again. (When the EVR mode
is released, the adjusted data is memorized.)
Y level
2.05 ± 0.03Vp-p
(Reference value)
H. rate
D/A level
H. rate
Fig. 3-3-2a

3.3.3 REC color (colour) level

Signal (A1) • Alignment tape [MH-1H]
(A2) • Ext. input
(A3) • Color bar signal [NTSC]
Mode (B1) • S-VHS
(B2) • PB
• REC (SP/EP) ¥ PB
(B3)
Equipment (C) • Oscilloscope
Measuring point (D1) • TP106 (PB. FM)
(D2) • PB color output of the LPF
External trigger (E) • TP111 (D.FF)
EVR mode (F1) • Jig RCU: Code "57"
EVR address (F2) • A:02 (Press remote controller
"0" and "2" keys)
Specified value (G) • SP: "B" x 125 ± 5%
• EP: "B" x 125 ± 5%
Adjustment tool (H1) • Jig RCU [PTU94023B]
(H2) • Digit-key remote controller
(H3) • LPF[PTU93006]
39 µH
1 kØ
PB. FM
from TP106
[ MAIN board ]
120 pF
Fig. 3-3-3a LPF
(1) Connect the adjustment tool (H3) to the measuring point
(D1).
(2) Apply the external trigger signal to D.FF (E) to observe
the PB color (colour) waveform at the measuring point
(D2).
(3) Play back the SP signal (A3) of the alignment tape (A1).
(4) Press the channel buttons (+, –) simultaneously to enter
the manual tracking mode. This also brings tracking to
the center (centre).
(5) Adjust tracking by pressing the channel buttons (+, –) so
that the PB color (colour) waveform becomes maximum.
Make a note of the higher PB color (colour) level as "B"
at this time.
(6) Record the signal (A3) in the S-VHS SP mode, and play
back the recorded signal.
(7) Set the VCR to the EVR mode by transmitting the code
(F1) from the Jig RCU.
(8) Set the EVR address to (F2) by pressing the button of
the digit-key remote controller.
(9) Adjust with the channel buttons (+, –) on the VCR (or on
the remote controller) so that the higher level channel
becomes the specified value (G) of the note "B" level as
shown in Fig. 3-3-3b. (Adjust before recording, then con-
firm it by playing back.)
Y level
1.00 ± 0.05 Vp-p
EE Y level
(See Fig. 3-3-3a.)
180 µH
629 [kHz]
PB COLOR
(PB COLOUR)
180 pF
3-3