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5 . P L A Y B A C K L E V E L A D J U S T M E N T
Information
As this is the standard for adjusting the electro-
magnetic system, improper adjustment will cause
the following problems.
a. Adjustments in the recording block will be
incorrect and will be deteriorated and distor-
tion will be increased.
b. The Dolby standard level will be affected.
c. Compatibility will be lost.
o
DolbV output level shall be adjusted to 580m
(-4.7dBv) when playing the tape recorded at
200PWb/mm. But, as there is no 200PWb/mm
test
tape
at
present, we
have to
use
250PWb/mm test tapes.
o
When using a 250PWb/mm test tape, adjust
the results referring toFig. 5-a (New).
- 4.7dBv(580mV)- (-1dBv) : - 3.7dBv(653mV)
Use Fig. 5-b (Old) when adjusting CT-4141A,
cT-F7t7t & CT-F6161.
* 4 . 7 d B v - ( - 2 d B ) = - 2 . 7 d B v ( 7 3 2 m V )
The difference between the New and Old is in
the method of measuring magnetic flux density
of Dolby standard level(200PWb).
( o l d )
D I N S t a n d a r d
250PWb/mm
Dolby Standard
200PWb/mm
P h i l i p s S t a n d a r d
160PWb/mm
F i g . 5 - a
( N e w )
250PWb/mm
200PWb/mm
Adjustment
a. Connect an AC voltmeter to the output ter-
minal (No.15 & Ground or No.16 & Ground)
of the Dolby ass'y.
b. Turn the Dolby NR switch on.
c. Reproduce the signal of 333H2 (0dB) on the
test tape STD-341(250PWb/mm) and adjust
the output with VR-102 and VP"-202 so that
the AC voltmeter indicates -3.?dBv(653mV).
L - c h . . . . N o . 1 5 . V R - 1 0 2
R - c h . . . . N o . 1 6 . V P " - 2 O 2
I
l
I
mV meter
c
N o . 2 2 o o l ] )
, .-
J iloliE
3 d B
3 2
1 6 0 P W b / m m
F i g . 5 - b
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