JVC SR-VS30U User manual

SERVICE MANUAL
COPYRIGHT © 2003 VICTOR COMPANY OF JAPAN, LIMITED No.MB061
2004/1
DOUBLE CASSETTE DECK
MB061200312 TD-W271
TABLE OF CONTENTS
1 PRECAUTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3
2 SPECIFIC SERVICE INSTRUCTIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4
3 DISASSEMBLY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5
4 ADJUSTMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-13
5 TROUBLESHOOTING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-19
5
46
37
28
19
MIN MAX
INPUT LEVEL
COUNTER RESET
COUNTER RESET
STANDBY
STANDBY/ON ON OFF
PLAY
PHONES
POWER
REVERSE MODE
DOUBLE CASSETTE DECK
REC / REC MUTE PAUSE A B SYNCHRO DUBBING
DOLBY B-C NR HX PRO
PLAY
REC/PLAYBACK
B
AUTO REVERSE
3MOTOR SILENT MECHANISM
AUTO REVERSE
3MOTOR SILENT MECHANISM
PLAYBACK
A
DOLBY NR
B OFF C
AUTO TAPE SELECTOR / CONTINUOUS PLAY
NORM SPEED HIGH SPEED
UF -------------- China
U -------- Other Areas
Area Suffix

1-2 (No.MB061)
SPECIFICATION
Design and specifications are subject to change without notice.
Type Double cassette deck
Track system 4-track, 2-channel
Tape speed 4.8 cm/sec (1-7/8 inch/sec) (Normal)
9.5 cm/sec (3-3/4 inch/sec) (High)
Frequency response
(-20 dB recording) Type IV tape 20-17000Hz
30-16000 Hz (±3dB)
Type II tape 20-16000 Hz
30-15000 Hz (±3dB)
Type I tape 20-16000 Hz
30-15000 Hz (±3dB)
S/N ratio 58 dB (S = 315 Hz, k3 = 3%, N = A-weighted, Type IV tape)
The S/N is improved by about 15 dB at 500 Hz and by max.
20 dB at 1kHz ~ 10 kHz with Dolby C NR on and improved by 5 dB
at 1 kHz and by 10 dB at above 5 k Hz with DOLBY B BR on.
Improvement of MOL 4 dB at 10 kHz with Dolby C NR on.
Wow and flutter 0.08% (WRMS), ±0.2% (DIN/IEC)
Channel separation 10 dB (1 kHz)
Crosstalk 60 dB (1 kHz)
Harmonic distortion k3; 0.8% (Type IV tape, 315 Hz, 0 VU)
Heads Deck A METAPARM head for playback ×1
Deck B METAPARM head for recording/playback,
2-gap ferrite head for erasure; combination head ×1
Motors Electric govemed DC motor for capstan ×1
DC motor for reel ×1
DC motor for mechanism drive ×1 (For both decks A and B)
Fast forward/rewind time Approx. 110 sec. with C-60 cassette
Input terminals LINE IN (×1 circuit) Input sensitivity 80 mV (0 VU)
Input impeadance 50 kΩ
Output terminals LINE OUT (×1 circuit) Output level 300 mV (0 VU)
Output impeadance 5 kΩ
PHONES ×1 Output level 0.3 mW/8 Ω(0 VU)
Matching impedance 8 Ω- 1 k Ω
Other terminals COMPU LINK-3/SYNCRO ×2
Power requirement AC 220 V, 50 Hz
Power consumption With power on 17 W
With power standby 4.0 W
Dimensions 435 ×139 331 mm
Mass 5.0 kg

(No.MB061)1-3
SECTION 1
PRECAUTION
1.1 Safety Precautions
(1) This design of this product contains special hardware and
many circuits and components specially for safety purpos-
es. For continued protection, no changes should be made
to the original design unless authorized in writing by the
manufacturer. Replacement parts must be identical to
those used in the original circuits. Services should be per-
formed by qualified personnel only.
(2) Alterations of the design or circuitry of the product should
not be made. Any design alterations of the product should
not be made. Any design alterations or additions will void
the manufacturers warranty and will further relieve the
manufacture of responsibility for personal injury or property
damage resulting therefrom.
(3) Many electrical and mechanical parts in the products have
special safety-related characteristics. These characteris-
tics are often not evident from visual inspection nor can the
protection afforded by them necessarily be obtained by us-
ing replacement components rated for higher voltage, watt-
age, etc. Replacement parts which have these special
safety characteristics are identified in the Parts List of Ser-
vice Manual. Electrical components having such features
are identified by shading on the schematics and by ( ) on
the Parts List in the Service Manual. The use of a substitute
replacement which does not have the same safety charac-
teristics as the recommended replacement parts shown in
the Parts List of Service Manual may create shock, fire, or
other hazards.
(4) The leads in the products are routed and dressed with ties,
clamps, tubings, barriers and the like to be separated from
live parts, high temperature parts, moving parts and/or
sharp edges for the prevention of electric shock and fire
hazard. When service is required, the original lead routing
and dress should be observed, and it should be confirmed
that they have been returned to normal, after reassem-
bling.
(5) Leakage shock hazard testing
After reassembling the product, always perform an isola-
tion check on the exposed metal parts of the product (an-
tenna terminals, knobs, metal cabinet, screw heads,
headphone jack, control shafts, etc.) to be sure the product
is safe to operate without danger of electrical shock.Do not
use a line isolation transformer during this check.
• Plug the AC line cord directly into the AC outlet. Using a
"Leakage Current Tester", measure the leakage current
from each exposed metal parts of the cabinet, particular-
ly any exposed metal part having a return path to the
chassis, to a known good earth ground. Any leakage cur-
rent must not exceed 0.5mA AC (r.m.s.).
• Alternate check method
Plug the AC line cord directly into the AC outlet. Use an
AC voltmeter having, 1,000Ωper volt or more sensitivity
in the following manner. Connect a 1,500Ω10W resistor
paralleled by a 0.15µF AC-type capacitor between an ex-
posed metal part and a known good earth ground.
Measure the AC voltage across the resistor with the AC
voltmeter.
Move the resistor connection to each exposed metal
part, particularly any exposed metal part having a return
path to the chassis, and measure the AC voltage across
the resistor. Now, reverse the plug in the AC outlet and
repeat each measurement. Voltage measured any must
not exceed 0.75 V AC (r.m.s.). This corresponds to 0.5
mA AC (r.m.s.).
1.2 Warning
(1) This equipment has been designed and manufactured to
meet international safety standards.
(2) It is the legal responsibility of the repairer to ensure that
these safety standards are maintained.
(3) Repairs must be made in accordance with the relevant
safety standards.
(4) It is essential that safety critical components are replaced
by approved parts.
(5) If mains voltage selector is provided, check setting for local
voltage.
1.3 Caution
Burrs formed during molding may be left over on some parts
of the chassis.
Therefore, pay attention to such burrs in the case of pre-
forming repair of this system.
1.4 Critical parts for safety
In regard with component parts appearing on the silk-screen
printed side (parts side) of the PWB diagrams, the parts that are
printed over with black such as the resistor ( ), diode ( )
and ICP ( ) or identified by the " " mark nearby are critical
for safety. When replacing them, be sure to use the parts of the
same type and rating as specified by the manufacturer.
(This regulation dose not Except the J and C version)
Good earth ground
Place this
probe on
each exposed
metal part.
AC VOLTMETER
(Having 1000
ohms/volts,
or more sensitivity)
1500 10W
0.15 F AC TYPE

1-4 (No.MB061)
SECTION 2
SPECIFIC SERVICE INSTRUCTIONS
This service manual does not describe SPECIFIC SERVICE INSTRUCTIONS.

(No.MB061)1-5
SECTION 3
DISASSEMBLY
3.1 Enclosure section
3.1.1 Removing the top cover
(See Fig.1)
(1) Remove four screws Aretaining the top cover from both
side.
(2) Remove two screws Bretaining the top cover from the
back side.
(3) To remove the top cover, slide in direction of arrow and lift
away (refer to Fig.1).
Fig.1
3.1.2 Removing the front panel assembly
(See Fig.2, 3)
(1) Remove the top cover as described in above.
(2) Remove the three screws Cretaining the front panel as-
sembly from bottom side.
(3) Release the front panel assembly from two pawls in the
front and bottom sides and draw it to the front side.
(4) Disconnect all connectors between the mechanism assem-
bly, front panel assembly and main board.
Fig.2
Fig.3
A
A
B
M
B
Top cover
CPawl C C
Pawl
Front panel assembly
Pull 2
Pull 2
Push 1
Push up with a screwdriver, etc. 1

1-6 (No.MB061)
3.1.3 Removing the mechanism assembly
• Although the mechanism assembly can be removed without
detaching the front panel assembly, it is recommended to de-
tach the front panel assembly to do the work with ease.
(1) Remove the two screws Dor two screws Efrom the cor-
ners of the mechanism. (Fig.6)
(2) Open the door and remove the mechanism assembly.
(At this time, door lock arm spring and door lock arm are re-
moved together with.)
(3) For moving the mechanism assembly only, disconnect the
following wirings.
a) Mechanism assembly side (Fig.5)
Top side connector of the cam switch board (CN2).
Connector of the motor board (CN1). (Board to board
connector)
b) Main board side (Fig.4)
Disconnects CN802 from mecha control board,
CN801 from switch/volume board and CN861 from
headphone jack board.
Disconnect wire coming from the head mount assem-
bly CN811 at deck A and CN815 at deck B.
Remove one screw Fand remove one GND wire
from mechanism control board.
3.1.4 Removing the eject arm assembly
(Fig.6)
(1) Remove the screws Gretaining the eject arm assembly
and pull it out.
Fig.4
Fig.5
Fig.6
Main board
Mechanism control board
CN811
CN861
CN801
CN802
CN815
From DECK A
From DECK B
DECK A
From Mechanism
control board
From Headphone jack
board
From Switch/
Volume board
L
DECK B
F
Motor
board
Motor
board
Motor
board
Motor
board
Mechanism
control
board Mechanism
control
board
Mechanism control board
Cam
switch
board
Cam switch board
DECK B DECK A
Cam switch board
Cam
switch
board
DECK B DECK A
DDGGE E

(No.MB061)1-7
3.1.5 Removing the mechanism holder and door assembly
(Fig.7, 8)
(1) Remove four screws Hretaining the mechanism holder.
(2) Remove the damper assembly (for easy reassembling
work).
Insert an originary (-) screwdriver or the like in to the gap
between the damper and the front panel to disengage the
pawl, and draw the damper assembly outwards. (See
Fig.7)
(3) Remove the arm shaft of the cassette holder (door assem-
bly) from the mechanism holder. (The door spring is en-
gaged with the door side by the longer side.) (See Fig.8)
(4) Remove the eject spring from lock lever and mechanism
assembly. (See Fig.8)
Fig.7
Fig.8
Pawl
How to remove damper
Cassette door
Longer side
Shorter side
Mechanism assembly
door spring
eject spring
Lock lever
How to engage the door and eject spring

1-8 (No.MB061)
3.1.6 Removing the switch & volume board
(Fig.9)
(1) After removing the mechanism holder, proceed to the fol-
lowing steps.
(2) Pull out the INPUT volume knob.
(3) Remove four screws J, one screw Nand cap retaining the
switch/volume board.
(4) Lift the board right upwards to remove it since it is connect-
ed to the key switch board with connector pins (CN603/
CN604).
(5) Disconnect CN602 coming from Mechanism control board
(CN702).
3.1.7 Removing the headphone jack board
(Fig.9)
(1) After removing the switch/volume board, pull the head-
phone jack board outwards while pushing it down toward
the bottom side to remove it.
3.1.8 Removing the key switch board
(Fig.9)
(1) Remove one screw K(Deck A or B) retaining the board.
(2) Do the same for the other side.
Fig.9
3.1.9 Removing the main board
(see Fig.4 and 1)
(1) Remove three screws Lretaining the board.
(2) Remove four screws Mretaining the board to the rear pan-
el.
3.1.10 Reassembling procedure of the front panel assembly
(1) Attach the key switch board to the panel with two screws.
(2) Attach the mechanism holder to the front panel assembly
with four screws.
(3) Put the door assembly on the front panel.
(4) Engage the door spring properly.
(5) Install the damper. (Push the pawl side last to engage it.)
(6) Install the mechanism assembly.
(7) Attach the mechanism control board to the panel with two
screws.
(8) Install the eject arm assembly.
(9) Attach the switch/volume board to the panel with five
screws.
(10) Hook the eject spring between lock lever and mechanism
assembly.
Mechanism control board
Key switch board
Switch/Volume board
Headphone jack board
Key witch board
Key switch board
Cap
N
JH HKHKH J
CN604 CN603
CN602
CN702
J

(No.MB061)1-9
3.2 Cassette mechanism section
3.2.1 Removing the head mount assembly
(Fig.10 and 11)
(1) Remove the FPC holder from the mechanism frame in the
direction indicated by the arrow (A).
(2) Remove three screws Aretaining the head mount assem-
bly.
3.2.2 Removing the pinch roller assembly
(Fig.10 and 12)
(1) Remove the pinch roller and pinch roller spring, refer to
Fig.12.
Fig.10
Fig.11
Fig.12
Mechanism A
Pinch roller (left) Pinch roller (right)
Head mount assembly
Head mount assembly
Head base
FPC Holder
(A)
A
Pinch roller
(left)
Pinch rolle
r
(right)
Pinch rolle
r
spring
Pinch roller
spring
Pawl
Pawl

1-10 (No.MB061)
3.2.3 Removing the FM bracket/Capstan motor assembly
(Mechanism A and B)
(1) Remove soldering of connector FM on reel motor board.
(Fig.13)
(2) Remove three screws Band disengage two pawls, and
then the FM bracket and the capstan belt can be removed.
(Fig.13 and 14)
(3) Remove two screws Cretaining the capstan motor from the
FM bracket. (Fig.13)
(4) For reengaging the capstan belt, refer to Fig.14.
Fig.13
Fig.14
3.2.4 Removing the flywheel assembly
(Fig.15)
(1) Remove two screws Dand remove the shield plate.
(2) Pull up the flywheel (L) and (R), and remove them.
3.2.5 Removing the reel motor board
(Fig.15)
(1) Remove four soldering of the reel motor and actuator mo-
tor, and remove the reel motor board.
Fig.15
Pawl
Pawl
Reel motor board
Connector FM
Capstan motor
FM bracket
B
B
B
C
Capstan belt
Reel motor
Reel motor board
Soldering
Soldering
Actuator motor
Flywheel (R) Flywheel (L)
Shield plate
D

(No.MB061)1-11
3.2.6 Removing the reel motor assembly
(Fig.16)
(1) Remove two screws Efrom rear of chassis and remove the
reel motor assembly toward upward.
3.2.7 Removing the actuator motor assembly
(Fig.16)
(1) Remove two screws Ffrom rear of chassis and remove the
actuator motor assembly toward upward.
Fig.16
3.2.8 Removing the mechanism board
(Fig.17)
(1) Remove one screw Gretaining the board.
(2) Release the mechanism board from five pawls.
(3) For gearing between the mechanism board and control
cam, see the magnified illustration in a circle.
Fig.17
Reel motor assembly
Mechanism board
A
ctuator motor assembly
EF
Mechanism board
Pawl
Pawl
G

1-12 (No.MB061)
3.2.9 Removing the control cam
(Fig.18 and 19)
(1) Release the control cam from two pawls. (Fig.18)
(2) For assembling the control cam, fits azone (groove) ofcon-
trol cam to a position of pinch lever and bzone (groove) to
b position of head base shaft. (Fig.18 and 19)
3.2.10 Removing the actuator gear A and B (small)
(Fig.18)
(1) Release the actuator gear A (small) from one pawl and re-
move it toward upward.
(2) Release the actuator gear B (small) from one pawl and re-
move it toward upward.
3.2.11 Removing the actuator gear (large)
(Fig.18)
(1) After removing the control cam, actuator gear A (small) and
actuator gear B (small), remove the actuator gear (large).
Fig.18
Fig.19
Pinch lever Control cam
Actuator gear
(large)
Control cam
(chassis side)
zone
zone
b
a
Actuator gear A
(small)
Actuator gear B
(small)
Pawl
Pawl
Pawl
Pinch lever
b
a
Head base shaft

(No.MB061)1-13
SECTION 4
ADJUSTMENT
4.1 Measuring instruments required for adjustment
(1) Low - frequency oscillator (oscillation frequency 50 Hz - 20
kHz, 0 dB output with 600 Ωimpedance)
(2) Attenuator (600 Ωimpedance)
(3) Electronic voltmeter and oscilloscope
(4) Standard tapes
VT712 (tape speed, wow and flutter measurement)
VT727 (400 Hz reference level)
VT742 (63 Hz, 1 kHz, 12.5 kHz) (play back frequency)
VT705 (12.5 kHz) (azimuth)
(5) Recording reference tapes
AC-225 (Normal), AC-514 (TDK SA) (CrO2)
AC-713 (TDK MA) (Metal)
(6) 600 Ωresistors (for attenuator matching)
(7) Distortion meter (band pass filter)
(8) Torque gauge (cassette) for CTG-N, TW2111, TW2121,
TW2231 and TW2241, mechanism adjustments
(9) Wow & flutter meter
(10) Frequency counter meter
(11) M300 gauge
(12) Band pass filter
4.2 Measurement conditions
(1) Power supply voltage (your local voltage)
(2) Standard position of the switch and volume knob Switches
and volume knobs setting position
(3) Standard level (0 dBs) is 0.775 V unless otherwise speci-
fied.
(4) The reference value of recording input level is LINE IN level
of a signal whose LINE OUT level is -8 dBs and H.PHONE
OUT level is -24 dBs.
4.3 Location of adjustment
AC230 V 50 Hz : B/E/EN version
AC120 V 60 Hz : J/C version
AC230/127/110 V 50/60 Hz : UT/U version
INPUT LEVEL : MAXIMUM
DOLBY NR : OFF
REVERSE MODE :
R
L
LR
LR
R
R L
L
R
R
L
L
DECK B
REC LEVEL
adj.
DECK A
PB FREQ.
RESPONSE adj.
DECK A
PB LEVEL
adj.
VR211 VR111
VR212 VR112
L8401
VR226
VR216
L2401
L1401
VR246 VR146
15
CN845
VR216 VR116
VR217 VR117
NORMAL SPEED adj.
HIGH SPEED adj.
B7101
H.SPEED
TP
BIAS
FREQUENCY DECK A
DECK A
VR701 VR703
VR702 VR704
DECK B
DECK B
DECK B
REC FREQ.
RESPONSE
adj.
DECK B
PB LEVEL
adj.
HX PRO adj
DECK B
FREQ.
RESPONSE
adj.
+
GND
+
-
V
+
-
V
F. COUNTER
(BIAS
FREQUENCY
adj.)
DC VOLTMETER
(HX PRO adj.)
1
CN845
5
470k
(L)
(R)
Connection of CN845

1-14 (No.MB061)
4.4 Mechanism adjustment
Before using test tapes, tape transporting past should be demagnetized.
* Adjustments required after head replacement are marked with an asterisk(*).
Item Conditions Adjustment and Confirmation Standard value Adjust point
* Adjusting
Head
azimuth
Test tape : VT704
or VT705 (12.5 kHz)
Connect an electronic voltmeter to the LINE
OUT terminals.
Play back the VT704 (12.5 kHz) test tape.
Adjust the head angle with the screw (FWD
and REV) until the reading of the electronic
voltmeter becomes maximum for both
channels (phase difference must be "0".)
Repeat the adjustment in FWD and REV
modes as well as for the decks A and B.
1.
2.
3.
4.
Maximum Screws
(FWD, REV)
Adjusting
tape speed
(motor speed)
Test tape :
VT712 (3 kHz)
After adjustment
of normal speed,
then adjust high
speed.
For high speed
adjustment, set
the deck for play
mode and short
circuit between
B7101 and GND.
Connect a frequency counter to the LINE OUT
terminals.
Perform normal speed adjustment first, and
then do high speed adjustment.
Play back the VT712 test tape.
Adjust for decks A. :
Adjust VR701 for normal speed at 3000 Hz,
and VR702 for high speed at 6000 Hz.
Adjust for decks B. :
Adjust VR703 for normal speed at 3000 Hz,
and VR704 for high speed at 6000 Hz.
Difference in FWD and REV frequencies must
be less than 48 Hz.
1.
2.
3.
4.
Normal speed:
Deck A,B ;
3000 15 Hz
High speed:
Deck A,B ;
6000 30 Hz
Deck A :
Normal ; VR701
High ; VR702
Deck B :
Normal ; VR703
High ; VR704
1.
2.
Checking
wow and
flutter
Test tape : VT712 (3
kHz)
Connect a wow and flutter meter to the LINE
OUT terminals.
Play back the VT712 test tape.
Check to see if the reading of the meter is
within 0.17 % (WRMS).
1.
2.
3.
Less than 0.17 %
(WRMS)
Checking
play back
torque
Torque gauge :
TW2111 (FWD)
TW2121 (REV)
Employ a torque testing cassette tape
(TW2111[FWD] / TW2121[REV]) for the
checking, or remove the cassette cover and use
a torque gauge.
27 - 70 g cm
Checking
back
tension
Torque gauge :
TW2111 (FWD)
TW2121 (REV)
Employ a torque testing cassette tape
(TW2111[FWD] / TW2121[REV]) for the
checking, play the torque gauge and read the
back tension value to confirm that the back
tension is 1 - 5 g cm.
1 - 5 g cm
Checking
FF/REW
time
Tape : AC-225 Play back AC-225 tape in FF/REW mode, check
that the FF/REW time during tape running from
begin to end.
Less than 120 sec
REV Adj.
FWD
Deck B
REV Adj.
FWD
Deck A

(No.MB061)1-15
4.5 Electrical adjustment procedure
Play back
level
adjustment
Test tape :
VT727 (400 Hz)
Play back VT727 in FWD mode, then confirm
that the level at LINE OUT is -4.5 dBs 0.5 dB.
Adjust VR112/VR212 and VR117/VR217 so that
LINE OUT level becomes -4.5 dBs.
Difference level between Lch and Rch must less
than 0.5 dB at LINE OUT.
Confirm that difference playback level between
FWD and REV modes within 1.5 dB.
LINE OUT
-4.5 dBs 0.5 dB
Phone Out
-21 dB
+2.5 dB -1.5 dB
Deck B
L : VR117
R : VR217
Deck A
L : VR112
R : VR212
Check and Adjustment
Checking
DOLBY
circuit
(Rec. mode)
(BIAS-CUT)
Signal input: LINE IN Cal. level :
400 Hz, -8 dBs
Output terminal TP : NR IC831 53 and 8
pin.
DOLBY B
(Rec)
1Input signal
(Frequency, level)
Output raise value,
deviation value
1 kHz, Cal. - 40 dB
5 kHz, Cal. - 20 dB
1 kHz, Cal.
1 kHz, Cal. - 40 dB
5 kHz, Cal. - 20 dB
1 kHz, Cal.
+5.7 dB 2 dB
+3.5 dB 1.5 dB
0 dB +0.5 dB -1.0 dB
+16.2 dB +3 dB -2 dB
+2.9 dB 2.5 dB
0 dB 1 dB
DOLBY C
(Rec)
Play back
frequency
response
adjustment
Test tape :
VT742
(63 Hz, 1 kHz,
12.5 kHz)
Play back VT742 test tape, and adjust VR116,
VR216 (deck B) and VR111, VR211 (deck A) so
that deviation of 12.5 kHz to that of 1kHz is
0.5 0.5 dB (deck A) and 0 0.5 dB (deck B).
Then play back VT742 test tape to confirm that
deviation of 63 Hz to 1 kHz is +2 3 dB.
Difference level of
12.5 kHz from 1kHz
within 0.5 0.5 dB
(both decks A and
B)
Difference level of
63 Hz from 1 kHz
within +2 3 dB.
Deck B
L : VR116
R : VR216
Deck A
L : VR111
R : VR211
Bias
frequency
adjustment
Frequency counter
TP: CN845 pin 1
Tape: Metal
Mode: REC
Frequency counter
input impedance:
more than 470kohm
(see 3.3 Location of
adjustment.)
Connect frequency counter to the pin 1 of CN845
and adjust L8401 so that the counter reads
95 kHz.
95 kHz 1 kHz Deck B
L8401
Slave
oscillation
(HX PRO)
adjustment
DC. Voltmeter
TP: CN845
Lch (pin 3 - 4)
Rch (pin 3 - 5)
This step must be performed after the bias
frequency adjustment.
Load a metal tape and set the deck to the
recording mode.
Adjust L1401 and L2401 to minimize respective
DC voltage of CN845 (pin 3 - 4) at Lch and (pin 3
- 5) at Rch.
Minimum Deck B
L : L1401
R : L2401
*2
*3
*4
*5
Item Conditions Adjustment and Confirmation Standard value Adjust point
Item

1-16 (No.MB061)
Checking
recording
bias current
(Value
appearing
here are
just for
reference
Measuring point:
Both ends of
100 ohm resistor
connected to the
R/P head terminal
Connect 100 ohm resistor to the R/P head in
series, and measure voltage at both ends of the
resistor to check to see if measured voltage
meets the following requirements on both
channels.
In recording with metal tape, the bias current
is 1150 uA (1.15 mA).
In recording with CrO2tape, the bias current
is 700 uA (0.7 mA).
In recording with normal tape, the bias current
is 590 uA (0.59 mA).
Reference values
Metal tape:1150 uA
CrO2tape: 700 uA
Normal tape:590 uA
Input
sensitivity
level check
Supply at 1kHz signal to the LINE IN terminals
at -19 dBs, confirm that LINE OUT level is -
8dBs.
Confirm that difference level between left and
right within 2 dB.
LINE IN:
-19 dBs 2 dB
REC/PB
frequency
response
adjustment
LINE INPUT level:
Ref. -20 dB
(-40 dBs 2 dB)
NR switch : OFF
This step must be performed after the slave
oscillation adjustment.
Record the 1.25 kHz and 12.5 kHz signals at the
level of -20 dB (20 dB lower than the reference
level).
Playing back the recorded signals, adjust VR146
and VR246 so that the level of the 12.5 kHz
signal is 0 0.5 dB to the level of the 1.25 kHz.
12.5 kH level:
0 0.5 dB
higher than the
1 kHz level.
Deck B
L : VR146
R : VR246
REC/PB
sensitivity
adjustment
NR switch : Off
TAPE switch :
Normal
LINE INPUT level:
Ref. -20 dB
Normal:
-28 dBs 0.5 dB
CrO2/Metal:
-28 dBs 1 dB
(Difference between
L and R within
0.5 dB)
Deck B
L : VR126
R : VR226
6
7
*8
*9
1.
2.
Apply 400 Hz signal to the LINE IN terminals,
record 400 Hz signal at -20 dB input for both
(L and R) channels on a normal tape.
While recording the recorded signal and play it
back, adjust VR126(L) and VR226(R) so that
difference between the recording/playback
level and the reference level is
-28 dBs 0.5 dB on both channels.
1.
2.
Item Conditions Adjustment and Confirmation Standard value Adjust point
250 Hz 1 Hz 10 Hz 12.5 Hz
3 dB 5 dB
Spec. of freq. area
0 50 Hz 1 kHz 12.5 kHz
Response (dB)
Increase in high
frequencies
Decrease in
high frequencies
Low bias current
Appropriate bias current
High bias current
Frequencies

(No.MB061)1-17
Checking
dubbing
calibration
Test tape : VT742
Normal tape :
AC-225
-28 dBs +1.5/-2 dB
Maximum
output
check
Supply 1 kHz signal to the LINE IN terminal in
the Rec. monitoring mode, and read non-clipped
signal level at the LINE IN terminal.
LINE OUT:
more than 8 dBs
PHONES OUT:
more than -16 dBs
Checking
signal to
noise ratio
recording
play back
Normal:
More than 40 dB
CrO2/Metal:
More than 41 dB
10
11
13 Record a 1 kHz, -20 dB signal. Stop the input
by disconnecting from the terminal to perform
non-signal recording.
Play back the recorded part. Measure the
-8dBs recording output and the non-signal
recording output for comparison using an
electronic voltmeter. Check to see if the value
conforms to the standard value.
1.
2.
Item Conditions Adjustment and Confirmation Standard value Adjust point
Insert test tape VT742 into deck A and
AC-225 into deck B.
Dubbing the 1kHz signal of VT742 to AC-225
during high speed mode.
Playback the dubbing part of AC-225 (deck B)
and confirm that output level of 1kHz is
-28 dBs +1.5/-2 dB on both channels through
the band pass filter.
1.
2.
Checking
record/
playback
distortion
Normal:
Less than 2 %
CrO2/Metal:
Less than 3 %
12 Record a 1 kHz, -20 dB signal to LINE IN
terminals.
Play back the recorded part. Check the output
with a distortion meter to see if the value
conforms to the standard value.
1.
2.
Checking
erasing
coefficient
LINE OUT:
More than 55 dB
14 Apply a 400 Hz, +20 dB signal to the LINE
terminals.
Perform recording with the signal enhanced
by 20 dB.
Erase a part of the recording.
Measure the output difference between the
erased part and non-erased part to compare
with an electronic voltmeter.
1.
2.
3.
4.
For the measurement using a metal tape,
connect a band pass filter between the deck and
the electronic voltmeter.
Input
(400 Hz)
Tape deck
(recording,
erasing)
Band pass filter
(400 Hz)
Electronic
voltmeter

1-18 (No.MB061)
Checking
MPX filter
effect
Signal input:
LINE IN
Input level:
Maximum
19 kHz level:
-30 dB (including
18.99 to 19.01 kHz)
lower than 1 kHz
signal
15
Item Conditions Adjustment and Confirmation Standard value Adjust point
Connect an electronic voltmeter and
oscilloscope to the LINE OUT terminals.
Set the INPUT volume to the maximum
position.
Supply 1 kHz and 19 kHz signals reference
level to the LINE IN terminals respectively in
record/pause mode.
While recording monitor the 1 kHz and 19 kHz
signals respectively, confirm that level
difference between 19 kHz signal to 1 kHz
signal is more than 30 dB.
1.
2.
Checking
peak
indicator
calibration
16 Connect an electronic voltmeter to the LINE
OUT terminals.
Supply the 1 kHz reference signal (-4 dBs) to
the LINE IN terminals.
While rising the input signal level at the LINE
OUT so that each peak indicator is turned on
with the output level specified on the light.
1.
2.
3.
4.
Operation mode:
REC/PAUSE
Input frequency:
1 kHz
Signal input:
LINE IN
LINE OUT: -4 dBs
(Indicator reads at 0
position)
Indicator Signal level
(LINE OUT)
- 30
- 20
- 15
- 12
- 10
- 8
- 6
- 4
- 2
0
+ 2
+ 4
+ 6
+ 8
- 34 dBs 5 dB
- 24 dBs 4 dB
- 19 dBs 3 dB
- 16 dBs 3 dB
- 14 dBs 2 dB
- 12 dBs 2 dB
- 10 dBs 2 dB
- 8 dBs 1 dB
- 6 dBs 2 dB
- 4 dBs 2 dB
- 2 dBs 2 dB
0 dBs 2 dB
+ 2 dBs 2 dB
+ 4 dBs 2 dB

(No.MB061)1-19
SECTION 5
TROUBLESHOOTING
This service manual does not describe TROUBLESHOOTING.

(No.MB061)
AV & MULTIMEDIA COMPANY AUDIO/VIDEO SYSTEMS CATEGORY 10-1,1chome,Ohwatari-machi,Maebashi-city,371-8543,Japan
VICTOR COMPANY OF JAPAN, LIMITED
WPC
Printed in Japan