Tape Mechanism Electronics; Tape Adjustment & Check Table; Mechanism B Head Wires Soldering (Non-Dolby Version) - Philips FW-V720 Service Manual

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TAPE MECHANISM ELECTRONICS

B Photo Sensor
R1 (680R)
Motor
R2 (680R)
A Photo Sensor
* No Leaf switch & copper pattern
shorted together for Ferro version

Mechanism B Head Wires Soldering (Non-Dolby version)

Mechanism B Head Wires Soldering (Dolby B NR version)
9-5
1. B Rec Switch (REV)
Rec-R
2. B CrO2 Switch
CrO2*
3. B Rec Switch (FWD)
Rec-F
4. B Photo Out
Solenoid
5. B Solenoid
6. Vcc 12V
B-Mode
7. B Mode Switch
8. Gnd
9. A Solenoid
Solenoid
10. A Photo Out
11. A Mode Switch
12. Motor L
A-Mode
13. A CrO2 Switch
14. Motor H
CrO2*
Mechanism A Head Wires Soldering
Pink or
Red
White
Rec/Pb Head wire
Head connector pcb
Rec/Pb
1. +L ch (White)
Head
2. - ch (Black)
3. +R ch (Red)
4. E Head (Blue)
Erase
5. E Head (Yellow)
Head
For Normal Head
For Auto-reverse Head
Rec/Pb Head wire
Head connector pcb
1. +L ch (White) Rec/Pb
2. - L ch (Black)
Head
3. +R ch (Red)
4. - R ch (Blue)
5. E Head (Yellow)
Erase
6. E Head (Yellow)
Head
For Normal Head
For Auto-reverse Head
TAPE ADJUSTMENT & CHECK TABLE
ADJUST MOTOR SPEED
NORMAL SPEED
CHECK WOW & FLUTTER
DECK A & B
ADJUST AZIMUTH
DECK A & B
CHECK PLAYBACK FREQUENCY RESPONSE
DECK A & B
ADJUST BIAS CURRENT
DECK B
CHECK OVERALL FREQUENCY RESPONSE AND DISTORTION
Inject 3mV signals
100Hz, 250Hz, 1kHz,
10kHz, 12.5kHz
via or
3 4
Play
Head
Screen
(Gnd)
Inject 1kHz 8.85mV
via or
3 4
Head wire
connector pcb
1. White
2. Black
3. Red
SBC419A^ : 4822 397 30069
4. Blue
SBC420 : 4822 397 30071
5. Yellow
level(dB)
Head wire
connector pcb
1. White
2. Black
3. Red
4. Blue
5. Yellow
Published in Heiloo, Holland.
9-5
TEST
RECORDER MEASURE
READ ON
CASSETTE ON
MODE
PLAY B
SBC420 1 or 2
frequency
3150Hz
counter
PLAY A
LEFT RIGHT
SBC420 or
1 2
PLAY W&F-meter
3150Hz
LEFT RIGHT
PLAY FWD
SBC420 or
1 2
mV-meter
10kHz
PLAY REV #
LEFT RIGHT
or
1 2
mV-meter
SBC420 PLAY
LEFT RIGHT
SBC419A^
5 or 6
mV-meter
RECORD
SBC420
LEFT RIGHT
SBC419A^
or RECORD B
SBC420
RECORDED or 2
1
PLAY B mV-meter
CASSETTE
LEFT RIGHT
SBC419A^
or
RECORD B
SBC420
RECORDED or
1 2
PLAY B THD-meter
CASSETTE
LEFT RIGHT
# For Auto-reverse version only
* If high frequencies are not within limits, decrease bias and re-measure.
If distortion is too high, increase bias and re-meaure
^ Not applicable for Ferro version
level(dB)
8dB 6dB 8dB
f(Hz)
80 250 4k 12.5k
figure. 1
1/3/16
ADJUST
with to
3620 3150Hz – 0.5%
check 3150Hz -0.8/+1.8%
check †0.4 % DIN
left hand screw
max. output level
& left=right
right hand screw
check
limits see fig.1
3773 995mV
check
750mV – 1.5dB
check limits see fig. 2 *
check †3% *
8dB 6dB 8dB
10dB (HSD) 10dB (HSD)
f(Hz)
100 250 4k 10k
figure. 2