Philips N4450 Guide De Service

Service
Information
A. Modifications in recorders
. Version WR09
in recorders. marked from WR09/243
resistors in the amplifier have been replaced:
Original
R:3/R103
R4/R104 75
22
R9/R109 820
•all resistors 1/'8 w 5
This modification has been made to improve
of the recording amplifier.
. In recorders, marke«l trom WH09/303.
cornparators 84 have been provided
dampers consist of two plastic
a siheon liquid. For the eode numbers
the sequence of mounting. see Fig. I.
Note:
The two plastic discs 'with silicon
together in a special manner.
no account be Separated when they are mounted.
. in recorders. marked from WR09/304
(2.2 kV! - 1/8 W 5 has been addeci on p.c. board
Fig. 2). Further7nore, thc diodes DIO and Dll
on the RESET/AUTO.MATIC
replaced b}' This
introduced because the recorder
moment when the remote control
. In recorders. marked from W
1.703 and 1,704 and the capacitors
left out. In recorders, marked
have been reintroduced. to avoid motor
. In recorders. marked from WR09,'309.
replaced; the value was 560 2 and is now 1.5 ke (safety
resistor; code number 4822 110
•220 g F - 25 ) has been replaced
V number 124 20473)
becomes smaller. and therefore
push against the capacitor anymore
. In recorders, marked from WR09 /309.
cations on p.c. I have been made (see Fig.
- the
have been enlarged:
- the lampholders have been left out because the connecting
wires of the lamps are soldered
. In recorders. marked from WR09/311.
been fitted between switch SK5 and unit PIO (PRE-EMPHASIS/
SPEED SELECTOR t'NIT).
This modification has been introduced
between track 3 and track I.
In from WR091323.
cations have been made on p.c. board
- the print tracks have been modified;
- the diodes 0277. 278, 279. 280, 281. 282 and the resistors
R 232. are litted to the component
. Version WRIO
recorders. marked from WRIO/334.
(ZSC931i has been replaced by BD437. The code number
this transistor is 4822 130 40982.
Note:
Under code number 4822 130 40899. transistor
be supplied by Service for the time
also be used instead of 2SC931.
. In recorders, marked from WRIO/334.
has been increased from
Therefore. the PLAYBACK UNIT
SPEED SELECTOR UNIT have been modified.
ERVICE
CS39085
PHILIPS
the following
value New value
100 kn
kQ 7.5 kn
kn 270
the dynamics
the tape tension
with dampers. These
discs between which there is
of the new parts and
liquid) have been pressed
'Kherefore, the discs must on
, resistor R 202
2 (see
.BZ-xss,'C3V3)
REVERSE UNIT P2U1 have been
modification has been
sometimes stopped at any
unit NO 719 was used.
the coils 1.701. 1.702.
C703 and C 704 have been
from WR09,'309. the capacitors
sparks.
resistor R39 has been
and capacitor C 14
by a capacitor of 220
As a consequence.
the roll shutter 176 cannot
the following modifi-
3):
soldering the
direct to the p.c. board.
a screening plate has
to prevent crosstalk
the following modifi—
2 (see Fig. 2):
side.
transistor TS201
of
D330DSD will
being. This transistor
the frequency range
HL to 25,000 Hz at 19 cm/s.
and the PRE-EMPHASIS/
The new units
Copy„ght
RECORDERS
have the following
- PLAYBACK UNIT
- PRE-EMPHASIS/spEED
. Version WRII
In recorders. marked
been provided with a conducting rubber ring and an earthing
spring to eliminate the static charge.
The new reel discs
code number is 4822
B. Addenda to the Service
. Modified adjusting method for RECORDING UNIT P4/P104
Recorder in
position Recording
'X.tentiometer
at minimum
Input: BU2 TAPE
Output: BV5 MONITOR
BV2 TAPE
Input:
BU5 MONITOR
Output:
BV2 TAPE
Input:
BU5 MONIfOR 5/2
Out put :
BU2 TAPE
Input:
Output: BU5 MONITOR
BUA PHONO 6/2
Output:
BU2 TAPE
input:
MONITOR
Output:
—
BÜ4 PHONO 7/2
Out put
Note:
To avoid that the bias
oscillator unit P9 must
Correction of the adjustment
With this adjustment.
. [n some cases it may occur that the magnetic field of the
ring on the pulley of capstan motor M3, decreases. This may
be ascertained if the matput voltage
measured.
The table below states these
Tape speed
4.75 cm/s
9.5 crn/s
19 Crn/s
can
In part I of the Sewice Manual. the impression is created that
this circuit is protected
However. tho output
to too strong inpu& signals.
NV, PHILIPS' GLOEILAMPENFABRIEKEN
1974-01-02
N4450
AR 73-12
code numbers;
4822
SELECTOR UNIT 4822
from WRII ,/335. the reel discs,
can be used instead of the old ones. The
52S 10293.
Manual
- "TAPE" - "B" - "ST" -
"REC" at maximum; other
333 A - 0.1 v
IN„/OUT 3/2
to be adjusted
3/2
with R4 on
IN!OUT 5/2 333 -
5/2 to be adjusted
with on
IN/OUT 5/2 333 H?. - 1 v
to be adjusted to i V With
recording control
IN/OUT 3/2
333 Hz - 1 v
value to be
a,'2
V •x V (x = max.
O.S V). The
with respect
halved with
to be adjusted
with R9 on
IN/ov•r 5/2
5/2 value to be measured
0.8 The difference
with respect
be halved with
P105. [f
difference voltage
respect to I V is to be
halved again.
to be adjusted
with R9 on
current is also measured. the
be taken out of the recorder.
of the bias current.
switch SK3 "B-A" must be in position
Of pulse head K4 is
voltages for various
Output voltage K4
54 mv
110 mv
175 mv
from short-circuit ot the Output.
stage is protected only from
• Concern Semce
218 30132
30153
have
- "9.5"
to V
P5
v
to V
P105
"REC"
measured
diilerenee
to V to be
R4 on P5.
to 1.5 mV
p4
to I V to
R4 on
the
with
to 1.5 mV
P104
tape speeds.
tailing owing