Sony BM-87DST Service Manual ▷ View online
– 17 –
SECTION 4
MECHANICAL ADJUSTMENTS
PRECAUTION
1. Clean the following parts with a denatured alcohol moistened
swab :
record/playback/erase head
pinch roller
rubber belts
capstan
2. Demagnetize the record/playback/erase head with a head demag-
netizer.
3. Do not use a magnetized screwdriver for the adjustments.
4. After the head hight adjustments, apply suitable locking com-
4. After the head hight adjustments, apply suitable locking com-
pound to the parts adjusted.
5. The measurement and adjustments should be performed with the
rated power supply voltage unless otherwise noted.
Torque Measurement
Mode
Torque Meter
Meter Reading
Forward
CQ-102C
20 to 45 g • cm
(0.28 to 0.62 oz • inch)
Fast Forward
CQ-201B
80 to 200 g • cm
Rewind
(1.12 to 2.77 oz • inch)
Forward
CQ-102C
4 to 8 g • cm
Back Tension
(0.056 to 0.11 oz • inch)
Tape Tension Measurement
Mode
Tension Meter
Meter Reading
Forward
CQ-403A
100 to 170 g
(3.53 to 5.99 oz)
Forward Torque Adjustment
Torque meter
Meter reading
Procedure
Adjust the forward torque by
CQ-102C
20 to 45 g • cm
replace the spacer shown in
(0.28 to 0.62 oz• inch)
below chart.
Spacer
Part No.
t
3-307-493-01
0.1
3-307-493-11
0.15
3-307-493-21
0.2
3-307-493-31
0.25
Head Height Adjustment
Procedure :
1. Insert the mirror cassette (CQ-009C).
2. In playback mode and viewing from the front, adjust the head
1. Insert the mirror cassette (CQ-009C).
2. In playback mode and viewing from the front, adjust the head
heights to eliminate tape curl and tape twist at shown by arrows.
3. After the adjustments, apply suitable locking compound to
screws.
Part No.
t
3-578-138-01
0.1
3-578-138-11
0.2
nylon washer
(Taku-up side)
reflector
yoke plate
reel table magnet
tape
head
(rec / PB / erase)
Shim, head height
adjustment
adjustment
tape guide
– 18 –
PRECAUTION
1. Switches and controls should be to set to the positions as fol-
lows unless otherwise specified.
• Switch positions
POWER switch
: ON
AUTO STOP switch
: ON
SPEAKER switch
: BULT-IN
TONE control
: max (H)
VOLUME control
: mechanical mid
SPEED CONTROL switch
: OFF
REVERSE TIME control
: 0
2. Standard Input Level :
TELEPHONE PICKUP jack : 300
Ω
0.77 mV (-60 dB)
3. Standard Output Level :
Speaker
: 8
Ω
0.775 V (0 dB)
SECTION 5
ELECTRICAL ADJUSTMENTS
Record / playback / erase Head Azimuth Adjustment
Procedure :
1. Mode : Playback (LISTEN)
1. Mode : Playback (LISTEN)
earphone jack
10k
Ω
level meter
test tape
P-4-A063
(6.3kHz, –10dB)
P-4-A063
(6.3kHz, –10dB)
2. Turn the adjustment screw to obtain the maximum reading on
level meter.
Adjustment should be finished with the screw in tightening di-
rection.
Adjustment should be finished with the screw in tightening di-
rection.
3. After the adjustment, lock the adjustment screw with suitable
locking compound.
Adjustment Location : record / playback / erase head
Tape Speed Adjustment
Setup :
Mode : Playback (LISTEN)
test tape
WS-48
(3kHz, 0dB)
tape end portion
WS-48
(3kHz, 0dB)
tape end portion
frequency counter
earphone jack
Procedure :
SPEED CONTROL switch : OFF
1. TAPE SPEED switch : 4.8cm/s
1. TAPE SPEED switch : 4.8cm/s
Adjust RV602 to obtain a 3,010Hz frequency reading.
Standard value : 3,000 - 3,020Hz
Standard value : 3,000 - 3,020Hz
2. TAPE SPEED switch : 2.4cm/s
Adjust RV601 to obtain a 1,505Hz frequency reading.
Standard value : 1,500 - 1,510Hz
Standard value : 1,500 - 1,510Hz
Adjustment Location : servo board
mechanism deck
servo board
RV602
: Tape speed Adjustment (4.8cm/s)
: Tape speed Adjustment (4.8cm/s)
RV601
: Tape speed Adjustment (2.4cm/s)
: Tape speed Adjustment (2.4cm/s)
adjustment screw
head
(rec / PB / erase)
– 19 –
Pin No.
Pin name
I/O
Description
1 – 12
S12 – S23
–
Not used (OPEN).
13 – 16
KOUT 0 – KOUT 3
O
Key scan output.
17
MA50 - OUT
–
Not used (OPEN).
18
–
–
Not used (OPEN).
19
4.8 / 2.4 - OUT
O
Tape speed change signal output.
20
–
–
Not used (OPEN).
21– 23
COM0 – COM2
–
Not used (OPEN).
24
–
–
Not used (OPEN).
25
LCD - BIAS
–
Conect to VSS.
26 – 28
VLCD0 – VLCD2
–
Conect to VSS.
––––––––––––––––
29
FE-OUT
O
Fast-Erase control output. At Fast-Erase : “ L ” At the other : “ H ”
–––––––––––––––––––––
30
BIAS-OUT
O
BIAS control output. At DICT, TEL-REC : 0V At the other : 5.9V
–––––––––––––––––––––––––––
31
BRK-PG-OUT
O
Brake plunger output. Normal : 6.0 V STOP from FF/REW :
FF/REW
STOP
60ms
0V
–––––––––––––––––––––––––––
32
STOP-PG-OUT
O
Stop plunger output. Normal : 0 V STOP from FWD :
FWD
STOP
60ms
0V
33
VSS
–
GND
–––––––––––––––––
34
FWD-PG-OUT
O
FWD plunger output. At FWD : “ H ” At the other : “ L ”
––––––––––
35
FF-M-OUT
O
FF/REW motor output.
–––––––––––––––
36
REW-M-OUT
O
37
A-OFF-OUT
O
Motor Auto-off output.
Motor Auto-off (no cassette or after three minutes after STOP) : “ H ” At the other : “ L ”
38
STAND-BY
I
POWER switch input. POWER switch ON : “ H ” POWER switch OFF : “ L ”
39
TAB-IN
I
TAB (erase proof) detection switch input.
Cassette with TAB : “ L ” Cassette without TAB : “ H ”
40
MC-IN
I
Cassette detection switch input. With a cassette : “ L ” Without a cassette : “ H ”
41
CAS-IN
I
Cassette detection switch input. With a cassette : “ L ” Without a cassette : “ H ”
42
SR
I
S reel signal input.
43
TR
I
S reel signal input.
––––––––––
44
DICT-IN
I
HU-DICT key input.
At DICT key input of the hand control unit (HU-80) : “ L ” At the other : “ H ”
45
LTR-DET
I
LTR signal input. Count the rectangular pulse with microcomputer
SECTION 6
DIAGRAMS
6-1. EXPLANATION OF IC TERMINALS
IC109
µ
PD75308GF-J16-3B9 (SYSTEM CONTROL)
At motor FF
At motor REW
At the other
Pin35
L
H
H
Pin36
H
L
H
LTR
At FF/REW
600 to 4,800HZ
– 20 –
Pin No.
Pin name
I/O
Description
46
LTR-OUT
O
LTR signal output. At LTR oscillating :
5.3V
Output 80Hz for
three seconds.
three seconds.
At the other : 5.3V
47
REC-OUT
O
DICT, TEL-REC control output. At DICT, TEL-REC : “ H ” At the other : “ L ”
48
TEL-OUT
O
TEL-REC control output. At TEL-REC : “ H ” At the other : “ L ”
49
ALM-OUT
O
Alarm output. At alarm oscillating :
5.3V
2.05 kHz
50 – 53
KIN 0 – KIN 3
I
key scan input.
54
VDD
–
Positiv power source terminal of the microcomputer.
55
XT1
I
Microcomputer operation mode selection input. (Connect to VDD).
56
XT2
–
Not used (OPEN).
57
NC
–
Not used. Connect to VDD
58
X1
I
Input for clock oscillation (4.19MHz).
59
X2
O
Output for clock oscillation (4.19MHz).
–––––––––––––––
60
HU-LIS-IN
I
HU-LISTEN key input. At LISTEN key-in of the hand control unit (HU-80) : “ L ”
At the other : “ H ”
61
BS-IN
I
HU-BS key input. At BS key-in of the hand unit (HU-80) : “ L ” At the other : “ H ”
62
PB-OUT
O
Playback control output. At LISTEN : “ H ” At the other : “ L ”
–––––––––––––
63
MUTE-OUT
O
Amplifier mute output. At LISTEN, DICT, TEL-REC : “ H ” At the other : “ L ”
64
FS-IN
I
HU-FS key input. At FS key-in of the hand control unit (HU-80) : “ L ”
At the other : “ H ”
65
PR-IN
I
Foot switch LISTEN key input. At LISTEN key-in of the foot control unit (FS-75) : “ L ”
At the other : “ H ”
66
SEC-IN
–
Not used (Connect to VDD).
––––––––
67
LTR-IN
I
HU-LTR key input. At LTR key-in of the hand control unit (HU-80) : “ L ”
At the other : “ H ”
––––––––––––––
68
RESET
I
Microcomputer reset input. Normal : “ H ”
69 – 80
S0 – S11
–
Not used (OPEN).
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