Sony BVH-2000, Operation And Maintenance Manual

Page: 459 / 505

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12-11. AUDIO (Audio/CTL Head) BIAS LEAK
AND BIAS CURRENT ADJUSTMENT
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Connection; See section 8-4 connection 5.
Distortion Analyzer
Mode of VTR~ REC (Don't use alignment tape.)
Setting of Switches & Controls:
AUDIO Sel: AUDIO-I,2, or 3
REC Sw: OFF
TAPE/EE Sel: BVH-2000/PS/PM 00 model
INPUT
BVH-2000/PS/PM 02 model
BVH-2180/PS/PM 02 model
BVH-2500/P
INPUT ......TAPE
A-3 SEL Sw(SI/AE-03): LINE
Input Signal (AUDIO LINE IN)~
no signal I kHz/+8 dBm
1.
Open the level control panel and the rear panel. remove all
connectors
from the AP board, and take off the AP board.
Coming round to the rear, put the AP board in the VTR and
connect CN351, 353 and
to proper on
board.
Step. 2 Adjustment AP Board
Perform the following adjustments in record mode.
AUDIO-I: TPIOI-TPEIOI Minimum Bias Leak LVIOI
AUDIO-2: TP20l-TPE201
=
Minimum Bias Leak ~LV201
AUDIO-3: TP301-TPE301
=
Minimum Bias Leak ~LV301
the AP to
and connect all connectors to the board.
proper
Step 3.
Disconnect
AUDIO LINE INPUT and connect distortion
MONITOR OUTPUT.
selector to switch to
LINE and BIAS LEVEL AD] controls (RVl, 2, 3)/BE-04 to
midrange.
Connect oscilloscope across white lead and GND on the
Audio/CTL
RIP
head as shown below and adjust as follows.
AUD-3
Yellow
AUD-l
Black
AUD-2
Red
,~~- White
=
Maximum Level
=
Maximum Level ~ LV2/BE-03
AUDIO-3
=
Maximum Level QLV3/BE-03
(Oscilloscope)
For Model
Feed +8 dBm at I kHz to AUDIO-l(2, 3) LINE INPUT.
Turn Al(2, 3) BIAS LEVEL AD] controls (RV}, 2, 3)/BE-04 fully
cou nterclockwise.
Place machine
in record mode and turn the 3) BIAS
AD] controls 2, clockwise.
While playing back the recording, set AUDIO MONITOR
selector to AUDIO-l(2, 3), find out 0.5 dB over the peak position
and set AI(2, 3) BIAS LEVEL AD] controls (RVI, 2, 3)/BE-04
For BVH-2000/2180/PS/PM 02 Model, BVH-2500/P
Feed +8 dBm at 1kHz to AUDIO-l(2, 3) LINE INPUT.
Set TAPE/EE selector to TAPE and AUDIO MONITOR
selector to
Turn 3) LEVEL ADJ controls (RVL fully
counterclockwise and place machine in record mode.
Turn AI(2, 3) BIAS LEVEL AD] controls (RVI, 2, 3)/BE-04
clockwise and stops at 0.5 over the
as follows.
AUDIO
MONITOR
OUTPUT
Level
0.5 dB
Rotation of
-+-
BIAS
LEVEL
ADJ
12-10 BVH-2000(U/C)/PS/PM, BVH-2180(U/C)/PS/PM
BVH-2500(U/C)/P