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8.2 Erase voltage
- Insert cassette
Erase voltage :
Cr, Fe and Me
C
Fe:
12V
drive mechanism B
Cr:
18 V
re
LK 1
Me:
Erase
plug
Erase voltage, use
1:1000
capacitive voltage divider
- record
27 V
MeBschaltung 4
The bias voltage is 15...
30 V dependent on fre-
quency response, Cr: set- |
ting 18
V=0dB
(voltages in V measured
with a capacitive voltage
8.3 Bias voltage:
adjustment
switching factors.
- Insert cassette
To measure bias voltage use
_
Cr, Fe and Me
1: 1000 {e.g. CK 5) capacitive
tapes one after the
voltage divider:
other and start each
K1 (left channel wire head plug
tape for recording
LWB-6) or —
|
- Start with Cr.
.
K2 (right channel wire head plug
- Dolby NR off.
|
LWB-1).
| divider 1:1000 are indicated
in mV).
CK 5 ©
Setting: C 145 (left channel)
(KD
C 148 (right channel)
Switching factors compa-
red to Cr: Fe: - 3.7 dB
+ 0.5 dB (approx. 12 mV)
Me: + 3.6 dB+0.5 dB
(approx. 28.5 mV).
©
Test circuit 4
9.
MF head current
tape B
(Head voltage)
MF head current | a) Record
f=315 Hz
Set the left and right level
setting
- Insert Cr test cassette]
V,, = approx. 500mV
potentiometers (RECORD
(Head voltage)
448 A, side B,
+15dB
LEVEL) such that the volta-
(tape B.)
Cr, lEC ilnew —
measured at test points D1
1. possibility
(U 564 W)
Y |
(left channel) and D2 (right
- Dolby NR off
channel).
- Record, start
Adjust R 172 (left channel)
and R 184 (right channel)
so
that the
level
(ap-
prox.120 mV) is the same at
| both test points, D1 and D2
when playing back the re-
cording. Otherwise, change
the setting of the head cur-
rent potentiometers
on
making a new recording in
order to achieve the same
level at test points D1 and
D2 on recording and playing
back.
|
Test circuit 5
OC
D1
b) Playback , start
Playback of the recording
made under 9.1a)
c) MF head current con-
stant value level swit-
ching factors
Test circuit 2
9.2 MF-head current
F-he
a) Record
f
=315Hz
Turn the RECORD LEVEL
setting
- Insert Cr-test cassette
V,, = approx.
110 mV
left / right to maximum.
(Head voltage)
448, (blank tape sec-
+1.5dB
Adjust the input voltage so
record/ playback | < tion) side B, Cr, IEC Ii
}
that a voltage of 245 mV is
new (U 564 W) or in-
sert anequalizedtape
_- Dolby NR off
- Record, start
measured at test points D1
(left channel) or D2 (right —
channel),
On playing back the previ-
ously made recording, test
points D1 and
D2: must
show the same voltage le-
vel of 245 mV.
If
the value cannot be
achieved readjust the head
| current potentiometers
R 172 left and R 184 right.
'2. possibility
Playback of the recor-
ding made under 9. 1a)
| b) Playback, start
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