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9,2 PLAYBACK EOUALIZER ADJUSTMENT
l. Connect an millivoltmeter to ttre OUTPUT
terminals.
2. Set the TAPE switch to STD, tum VRros and
VR roe up to maximum positions, and VRloz
and VRroa to central Positions.
3. Play the 333H2, -20dB portion of the STD-
341A test tape, and adjust the OUTPUT volume
control to obtain a -20dBv (0.1V) reading in
the millivoltmeter.
4. Next play the 10kHz, -20d8
portion of the
same test tape, and adjust VRror (left channel)
and VRroz (right channel) to obtain a +ldB
level difference from the 333H2 output reading.
5. Then, play back the 14kHz, -20d8
(signal)
and confirm with the mV meter indication
that
the output
difference is over +0.5d8
when compared with the previously pXayed
333H2 signal. When less than 0.5d8, adjust in
accordance with the flow cbart on page 37.
6. Change the TAPE switch to the METAL posi-
tion (or CrOz or Fe-Cr positions), and check
that the frequency response referenced at 333H2
is within -4.0 t ldB at 10kHz.
9.3 PLAYBACK LEVEL ADJUSTMENT
The playback level must be carefully adjusted
owing to the fact that it will determine the Dolby
NR level.
1. Connect the millivoltmeter
to TP terminals
No. 26 (left) and No. 25 (right) on the mother
ass'y (The OUTPUT potentiometer may be set
at any position).
2. Replay the OdB part of the 333H2 test tone on
the STD-341A test tape. Adjust VRror :L-ch.
and VRroq :R-ch. until the respective indications
on the millivoltmeter become ldBv (1.12V).
9.4 LEVEL METER OdB ADJUSTMENT
1. Connect millivoltmeters to the TP terminals
No.30 (left) and No.29 (rieht) on the mother
ass'y.
2. Set the MONITOR switch to the SOURCE
position.
3. Apply a 333H2, -10dBv (316mV) signal to the
INPUT terminals, and adjust the INPUT level
controls so that the millivoltmeters read
-3dBv
(700mV).
4. Then immediately adjust VRaor (left)
and
VRaoz (right) in the indicator amplifier ass'y
so that the level meters read OdB at this time.
First turn VReol and VRsoz full around coun-
terclockwise, then tum back clockwise and stop
when the OdB segment lights uP.
5. Also check that the following readings are ob-
tained in the level meters when the input signal
level is changed.
Input Sisnal
Level Meter Reading
333H2, --5dBv (560mV)
333H2, -26dBv ( 50mV)
+5 t 2dB
- 1 6 r 2 d B
l C a m p l i f i e r
02s es o
*%,"d
l 6 E
-
vn,".dE
/
Lro"
, . 0 1 5
Fig. 9-3
Adiustment Points
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