Philips FW-V28 Service Manual page 39

TAPE MECHANISM ELECTRONICS
B Photo Sensor
Rec-R
CrO2
Rec-F
Solenoid
B-Mode
R1 (680R)
Solenoid
Motor
A-Mode
R2 (680R)
A Photo Sensor
CrO2
Mechanism B Head Wires Soldering (Non-Dolby version)
Rec/Pb Head wire
Head
connector pcb
For Auto-reverse Head
Mechanism B Head Wires Soldering (Dolby B NR version)
Rec/Pb Head wire
Head connector pcb
For Auto-reverse Head
9-5
1. B Rec Switch (REV)
2. B CrO2 Switch
3. B Rec Switch (FWD)
4. B Photo Out
5. B Solenoid
6. Vcc 12V
7. B Mode Switch
8. Gnd
9. A Solenoid
10. A Photo Out
11. A Mode Switch
12. Motor L
13. A CrO2 Switch
14. Motor H
Mechanism A Head Wires Soldering
Pink or Play
Red Head
Screen
(Gnd)
White
Head wire
connector pcb
1. White
Rec/Pb
2. Black
1. +L ch (White)
Head
3. Red
2. - ch (Black)
4. Blue
3. +R ch (Red)
5. Yellow
4. E Head (Blue)
Erase
5. E Head (Yellow)
Head
For Normal Head
Head wire
connector pcb
1. White
1. +L ch (White) Rec/Pb
2. Black
2. - L ch (Black)
Head
3. Red
3. +R ch (Red)
4. Blue
4. - R ch (Blue)
5. Yellow
5. E Head (Yellow)
Erase
6. E Head (Yellow)
Head
For Normal Head
TAPE ADJUSTMENT & CHECK TABLE
TEST
RECORDER
CASSETTE
MODE
ADJUST MOTOR SPEED
PLAY B
SBC420
NORMAL SPEED
3150Hz
PLAY A
CHECK WOW & FLUTTER
SBC420
DECK A & B PLAY
3150Hz
ADJUST AZIMUTH
PLAY FWD
SBC420
DECK A & B
10kHz
PLAY REV #
CHECK PLAYBACK FREQUENCY RESPONSE
PLAY
DECK A & B SBC420
ADJUST BIAS CURRENT
SBC419A
RECORD
DECK B
SBC420
CHECK OVERALL FREQUENCY RESPONSE AND DISTORTION
Inject 3mV signals
SBC419A
100Hz, 250Hz, 1kHz,
10kHz, 12.5kHz or RECORD B
SBC420
via or
3 4
RECORDED
PLAY B
CASSETTE
Inject 1kHz 8.85mV
SBC419A
or
RECORD B
via or
3 4
SBC420
RECORDED
PLAY B
CASSETTE
SBC419A : 4822 397 30069 # For Auto-reverse version only
SBC420 : 4822 397 30071 * If high frequencies are not within limits, decrease bias and re-measure.
level(dB)
8dB 6dB
80 250
4k 12.5k
figure. 1
9-5
ADJUST
MEASURE
READ ON
ON
with
3150Hz ± 0.5%
3620
or
1 2
frequency
counter
check 3150Hz -0.8/+1.8%
LEFT RIGHT
or 2
1
≤0.4 % DIN
W&F-meter check
LEFT RIGHT
left hand screw
or max. output level
1 2
mV-meter
& left=right
right hand screw
LEFT RIGHT
or 2
1
mV-meter
check limits see fig.1
LEFT RIGHT
3773
or
5 6
mV-meter
750mV ± 1.5dB
check
LEFT RIGHT
or
1 2
mV-meter limits see fig. 2 *
check
LEFT RIGHT
or
1 2
THD-meter check
LEFT RIGHT
If distortion is too high, increase bias and re-meaure
level(dB)
8dB 8dB 6dB
10dB (HSD)
f(Hz)
100 250
4k
figure. 2
to
995mV
≤3% *
8dB
10dB (HSD)
f(Hz)
10k
PCS 103 377