Jvc BR 6400 TR Service Manual Part 3

Page 1

5.5 DRUM SERVO CIRCUIT

No Item gm: '32: Signal Mode Description and Waveform
1 Drum Pulse TP-13 - PAL PAL . Connect oscilloscope to TP-13 of the Drum
Level Drum Color REC servo board.
Servo Bar l- 40 ms +1
more than 2 V
Jffl L
more than 2 V
Plaver (BF-5300TR) MH-2 PAL .Connect oscilloscope to TP-13 of the Drum
TP-13 Stair- P.B. servo board.
Drum Step . Supply a video signal to SYNC IN and set the
Servo SYNC switch to EXT position.
l¢ 40 m5 -l
more than 2 V
more than 2 V
2 Drum FG TP21 - PAL PAL .Connect oscilloscope to TP-21 of the Drum
(FreQUenCY Drum Color REC servo board,
Generator) Servo Bar . Confirm that the DRUM FG level becomes
Level more than 5 V911.
Plaver (BP-SSOOTR) MH-Z PAL , Connect oscilloscope to TPrZl of the Drum
TP-21 - P.B_ servo board,
Drum . Supply a video signal to SYNC IN and set the
Servo P.Br switch to EXT
. Confirm that the DRUM FM level becomes
more than 5 Vp-p.
b (Max. levellla (Min. level) 3 1.1
3 Drum AC TP-11 - PAL PAL . Connect oscilloscope to TP.11 of the Drum
Ripple Color REC servo board.
Bar . Confirm that the DRUM AC ripple level is less
than 30 mVp~p.
Wfij
Less than 30 mVp-p
Player (BP-SSOOTR) __
TP»11 - NIH-2 PAL ,Connect oscilloscope to TP-ll of the Drum
Stair- P.B. servo boardi
Step . Supply a video signal to SYNC IN and set the
P.B. switch to EXT.
. Confirm that the DRUM AC ripple level is less
than 30 mVp-p.
WW
Less than 30 mVpp

5-8

Page 2

Check Adiustment . . .
No. Item Point Parts Signal Mode . Description and Waveform
4 Drum TP-17 R128(NTSC) MH-S NTSC . Play JVC alignment tape (MH-E).
discriminator Drum Drum Stair- P.B. 2. Connect a digital voltmeter to TP-17 on the
Servo Servo step ) Drum servo board.
R97 (PAL) MHv2 PAL . Adjust R128 to obtain a DC voltage of 5.35 V.
Drum Stair- P.B. . Play JVC alignment tape (MH-2).
servo step . Similarly, adjust R97 to obtain a DC voltage of
5.35 V.
5 Drum TP-12 - PAL PAL . Connect oscilloscope to TP-l2 of the Drum
Flip-Flop Drum Color REC servo board.
Servo Bar . Confirm that the DRUM FLlP»FLOP level be-
comes 11 i 1 Vp-p.
r . -r
1 11 t1 Vp-p
# ,4
~ 40 ms -
6 DrumSampling TP-15 -- PAL PAL .Connect oscilloscope to TP-15 of the Drum
Position Drum Color REC servo board.
Servo Bar . Confirm the waveform as shown below.
Sampling pulse
11.2103 Vp-p
A
- _ 5.6 $0.4 msec (NTSC)
7.0 20.4 msec (PAL)
*7 Rec.CTL Delay TP-16 - PAL PAL . Connect oscilloscope to TP-16 of the Drum
(Pulse Width) Drum Color REC servo board.
Bar . Confirm that the REC CTL level becomes 9.5
t 1 Vp-p and 27 i 2 msec.
T
9.5 :1 qua
1
277172 msec
8 P.B.Switching Video out R95 MH-2 PAL . Connect oscilloscope to video out or TP-S of
Point or Drum Servo Stair- P.B. the Y board. Trigger the oscilloscope externally
TP-Q Y (CH-1 SW step (+ slope) with the signal from TP-12 of the
Normal Mode Phase) Drum servo board.

. Adjust R95 to position the trigger point 6.5

t 0.5 H from V sync.

6.5 _+_ 0.5 H

L Trigger point (Switching point)
(+1 I;

Equalizing
CPI-1 ) LI pulse , -- V. sync
4 H -

1. (Wm.

- 2.5H -

* Recorder unit only

59