JVC UX-T770R User manual

SERVICE MANUAL
MICRO COMPONENT SYSTEM
No.20993
Jun. 2001
COPYRIGHT 2001 VICTOR COMPANY OF JAPAN, LTD.
UX-T770R
UX-T770R
Contents
Safety Precautions
Important for laser products
Preventing static electricity
Disassembly method
Adjustment method
Flow of functional operation
TOC read
Maintenance of laser pickup
Replacement of laser pickup
Description of major ICs
1-2
1-3
1-4
1-5
1-16
1-20
1-21
1-21
1-22
Area Suffix
E ------ Continental Europe
EN ------- Northern Europe

UX-T770R
1-2
1. This design of this product contains special hardware and many circuits and components specially for safety
purposes. 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 performed 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 manufacturer`s 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
characteristics are often not evident from visual inspection nor can the protection afforded by them necessarily
be obtained by using replacement components rated for higher voltage, wattage, etc.Replacement parts which
have these special safety characteristics are identified in the Parts List of Service 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 characteristics
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 re-assembling.
5. Leakage currnet check (Electrical shock hazard testing)
After re-assembling the product, always perform an isolation check on the exposed metal parts of the product
(antenna 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, particularly any exposed metal part having a return
path to the chassis, to a known good earth ground.Any leakage current 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, 1,000 ohms per volt or more
sensitivity in the following manner. Connect a 1,500 10W resistor paralleled by a 0.15 F AC-type capacitor
between an exposed 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 meausre 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.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.
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
!
Burrs formed during molding may
be left over on some parts of the
chassis. Therefore, pay attention to
such burrs in the case of
preforming repair of this system.
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.
(Except the J and C version)

UX-T770R
1-3
Important for laser products
1.CLASS 1 LASER PRODUCT
2.DANGER : Invisible laser radiation when open and inter
lock failed or defeated. Avoid direct exposure to beam.
3.CAUTION : There are no serviceable parts inside the
Laser Unit. Do not disassemble the Laser Unit. Replace
the complete Laser Unit if it malfunctions.
4.CAUTION : The compact disc player uses invisible laser
radiation and is equipped with safety switches which
prevent emission of radiation when the drawer is open and
the safety interlocks have failed or are de
feated. It is dangerous to defeat the safety switches.
5.CAUTION : If safety switches malfunction, the laser is able
to function.
6.CAUTION : Use of controls, adjustments or performance of
procedures other than those specified herein may result in
hazardous radiation exposure.
VARNING : Osynlig laserstrålning är denna del är öppnad
och spårren är urkopplad. Betrakta ej strålen.
VARO : Avattaessa ja suojalukitus ohitettaessa olet
alttiina näkymättömälle lasersäteilylle.Älä katso
säteeseen.
ADVARSEL : Usynlig laserstråling ved åbning , når
sikkerhedsafbrydere er ude af funktion. Undgå
udsættelse for stråling.
ADVARSEL : Usynlig laserstråling ved åpning,når
sikkerhetsbryteren er avslott. unngå utsettelse
for stråling.
REPRODUCTION AND POSITION OF LABELS
WARNING LABEL
DANGER : Invisibie laser radiation
when open and interlock or
defeated.
AVOID DIRECT EXPOSURE TO
BEAM (e)
VARNING : Osynlig laserstrålning är
denna del är öppnad och spårren är
urkopplad. Betrakta ej strålen. (s)
VARO : Avattaessa ja suojalukitus
ohitettaessa olet alttiina
näkymättömälle lasersäteilylle.Älä
katso säteeseen. (d)
ADVARSEL :Usynlig laserstråling
ved åbning , når
sikkerhedsafbrydere er ude af
funktion. Undgå udsættelse for
stråling. (f)
CLASS 1
LASER PRODUCT
!Please use enough caution not to
see the beam directly or touch it
in case of an adjustment or operation
check.

UX-T770R
1-4
Conductive material
(conductive sheet) or iron plate
(caption)
Anti-static wrist strap
Preventing static electricity
Electrostatic discharge (ESD), which occurs when static electricity stored in the body, fabric, etc.is discharged,
can destroy the laser diode in the traverse unit (optical pickup). Take care to prevent this when performing repairs.
1.2. Handling the traverse unit (optical pickup)
1. Do not subject the traverse unit (optical pickup) to strong shocks, as it is a sensitive, complex unit.
2. Cut off the shorted part of the flexible cable using nippers, etc. after replacing the optical pickup. For specific
details, refer to the replacement procedure in the text.Remove the anti-static pin when replacing the traverse
unit.Be careful not to take too long a time when attaching it to the connector.
3. Handle the flexible cable carefully as it may break when subjected to strong force.
4. It is not possible to adjust the semi-fixed resistor that adjusts the laser power. Do not turn it
1.1.3. Handling the optical pickup
1. In order to maintain quality during transport and before installation, both sides of the laser diode on the
replacement optical pickup are shorted. After replacement, return the shorted parts to their original condition.
(Refer to the text.)
2. Do not use a tester to check the condition of the laser diode in the optical pickup.The tester's internal power
source can easily destroy the laser diode.
1.1.2. Ground yourself
1. Use an anti-static wrist strap to release any static electricity built up in your body.
1.1.1. Ground the workbench
1. Ground the workbench by laying conductive material (such as a conductive sheet) or an iron plate over
it before placing the traverse unit (optical pickup) on it.
1.1. Grounding to prevent damage by static electricity
Static electricity in the work area can destroy the optical pickup (laser diode) in devices such as DVD players.
Be careful to use proper grounding in the area where repairs are being performed.

UX-T770R
1-5
From behind the body, remove the seven screws A
retaining the rear panel.
After turning the body upside down, remove the two
screws Bretaining the rear panel.
Take out the rear panel from behind the body.
1.
2.
3.
Disassembly method
Removing the rear panel
(See Fig. 1 and 2)
After turning the body upside down, remove the two
screws Cretaining the front cabinet assembly.
After turning the body back to initial position, open
the CD door while pressing the upper OPEN button.
While moving the side panel (L) in the arrow
direction, remove the panel from the left side of the
body.
While moving the side panel (R) in the arrow
direction, remove the panel from the right side of the
body.
1.
2.
3.
4.
Removing the side panel (L) and (R)
(See Fig. 2 to 5)
AA
A
A
AFig. 1
Fig. 2
Fig. 3
Fig. 4Fig. 5
Rear panel
Front panel assembly
C
Side panel (L)
Side panel (R)
B
B
Rear panel
CD doorOPEN botton
Front panel assembly
Front panel assembly

UX-T770R
1-6
Remove the rear panel.
Remove the left and right side panels.
From the two connector CN603 and CN604 on the CD
servo control board, disconnect the card wires
outgoing from the connector CN304 on the power
amplifier board and the connector CN766 on the LCD
system CPU board.
Disengage the left and right engagements aand b
fixing the CD player unit by using a minus screw
driver, etc.
1.
2.
3.
4.
Removing the CD player unit
(See Fig. 6 to 8)
a
CD player unit CD servo control board
CN603
b
CD servo
control board
CN604
Fig. 6
Fig. 7
Front panel assembly
Fig. 8
CD player unit
Front panel assembly
Power amplifier board
CD player unit

UX-T770R
1-7
Remove the rear panel.
Remove the left and right side panels.
Remove the CD player unit.
Remove the five screws Dand Eretaining the heat
sink.
From the connector CN303 on the power amplifier
board, disconnect the card wire outgoing from the
connector CN34 on the head amplifier and
mechanism control board.
From the connector CN901 on the power supply
board, disconnect the connector wire outgoing from
the connector W306 on the power amplifier board.
Remove the one screw Fretaining the power
amplifier board.
Remove the power amplifier board from the two
connectors CN711 and CN712 on the LCD system
CPU board.
After removing the power amplifier board from the
key way c on the bottom chassis, take this board out
while raising it in the arrow direction.
1.
2.
3.
4.
5.
6.
7.
8.
9.
Removing the power amplifier board and
heat sink (See Fig. 9 to 11)
Power supply board
CN901
CN303
CN712
CN711
Heat sink
LCD system CPU board
Fig. 9
Fig. 10
Fig. 11
Heat sink
D
D
E
Power amplifier board
Power amplifier board Front panel assembly
c
cF
Bttom chassis

UX-T770R
1-8
Remove the rear panel.
Remove the left and right side panels.
From the right side of the body, remove the one
screw Gretaining the tuner board.
From the connector CN1 and CN2 on the tuner
board, disconnect the card wire outgoing from the
connector CN701 and CN702 on the LCD system
CPU board.
Remove each tuner board backward while releasing
the joint d.
1.
2.
3.
4.
5.
Removing the tuner board
(See Fig. 12 and 13)
Remove the rear panel.
Remove the left and right side panels.
Remove the CD player unit.
Remove the power amplifier board and heat sink.
From the connector CN701 on the LCD system CPU
board, disconnect the card wire outgoing from the
connector CN1 on the tuner board.
From the bottom of the body, disengage the
engagement e fixing the front panel assembly in Fig.
14 while pressing in with a minus screw driver, eta.
1.
2.
3.
4.
5.
6.
Removing the front panel assembly
(See Fig. 12 and 14)
LCD system CPU board
CN701 Tuner board
G
Fig. 12
Fig. 13
Fig. 14
Joint d CN1
Joint d
Tuner board
e
Front panel assembly
CN702
CN2

UX-T770R
1-9
Remove the rear panel.
Remove the left and right side panels.
Remove the CD player unit.
Remove the power amplifier board and heat sink.
Remove the four screws Hretaining the power
transformer and power supply board and the one
screw Iretaining the jack holder.
1.
2.
3.
4.
5.
Removing the power transformer and
power supply board (See Fig. 15 and 16)
Remove the rear panel.
Remove the left and right side panels.
Remove the CD player unit.
Remove the power amplifier board.
Remove the front panel assembly.
From inside the front panel assembly, remove the
four screws Jand Kretaining the cassette
mechanism unit.
From the connector CN33 on the head amplifier and
mechanism control board, disconnect the card wire
outgoing from the connector CN731 on the LCD
system CPU board.
1.
2.
3.
4.
5.
6.
7.
Removing the cassette mechanism unit
(See Fig. 17)
LCD system CPU board
CN731
Cassette mechanism unit
Head amplifier & mechanism
control board
CN33
Fig. 15
Fig. 16
Fig. 17
HH
Power transformer
Power supply board
I
Jack holder
Power supply board
K
J

UX-T770R
1-10
Remove the rear panel.
Remove the left and right side panels.
Remove the CD player unit.
Remove the front panel assembly.
Remove the cassette mechanism unit.
From inside the front panel assembly remove the two
screws Lretaining the function switch board.
From the connector CN782 on the LCD system CPU
board, disconnect the connector wire outgoing from
the connector CN802 on the operation switch board.
While sliding the two engagements ffixing the LCD
system CPU board, pull out this board.
After disconnect the connector CN801 on the
function switch board from the connector CN781 on
the LCD system CPU board, remove the respective
boards while pulling them upward.
1.
2.
3.
4.
5.
6.
7.
8.
9.
Removing the function switch board and
LCD system CPU board
(See Fig. 18 and 19)
LL
f
Operating switch board
CN802
LCD system
CPU board
CN782
Function switch board
LCD system CPU board CN781
CN801
Function switch board
Fig. 18
Fig. 19
f

UX-T770R
1-11
Remove the rear panel.
Remove the left and right side panels.
Remove the CD player unit.
Remove the front panel assembly.
Remove the cassette mechanism unit.
Remove the LCD system CPU board.
Remove the two screws Mretaining the operating
switch board.
Remove the MULTI-JOG button.
Remove the VOLUME and POWER / AUX buttons.
Take out the standby LED lens.
After removing four pawls gfixing the operating
switch board, remove the switch while pulling it in the
arrow direction.
Remove the two screws Nretaining the operation
switch board.
Remove the six pawls hfixing the operating switch
board.
1.
2.
3.
4.
5.
6.
7.
8.
9.
10 .
11 .
12 .
13 .
Removing the operating switch board
(See Fig. 20 to 22)
MULTI-JOG button
Operating switch board
MM
gStandby
LED lens
POWER / AUX button
VOLUME button
Operating switch board
N
N
h
Fig. 20
Fig. 21
Fig. 22
g
h
hh

UX-T770R
1-12
Cassette mechanism
Flywheel R
Trigger armHead mount
Fig. 1
Fig. 2
Playback / Recording &
eraser head
Flexible
board
Spring 1
Trigger arm
Head amplifier & mechanism
control P.C. board Flywheel R
Fig. 3
Playback / Recording &
eraser head Reversing azimuth
screw
Head
mount
Flexible
board
Spring 1
Head amplifier &
mechanism control
P.C. board
CN31
<Cassette mechanism section>
While shifting the trigger arms seen on the right side
of the head mount in the arrow direction, turn the
flywheel R in counterclockwise direction until the
head mount has gone out with a click (See Fig.1).
When the flywheel R is rotated in counterclockwise
direction, the playback / recording & eraser head will
be turned in counterclockwise direction from the
position in Fig. 2 to that in Fig. 3.
At this position, disconnect the flexible P.C. board
(outgoing from the playback / recording & eraser
head) from the connector CN31 on the head
amplifier & mechanism control P.C. board.
Remove the flexible P.C. board from the chassis
base.
Remove the spring 1 from behind the playback /
recording & eraser head.
Loosen the reversing azimuth screw retaining the
playback / recording & eraser head.
Take out the playback / recording & eraser head from
the front of the head mount.
The playback / recoring & eraser head should also
be removed similarly according to steps 1 to 7 above.
1.
2.
3.
4.
5.
6.
7.
8.
Removing the playback / recording &
eraser head (See Fig. 1 to 3)
Reassemble the playback head from the front of the
head mount to the position as shown in Fig.3.
Fix the reversing azimuth screw.
Set the spring 1from behind the playback / recording
& eraser head.
Attach the flexible P.C. board to the chassis base, as
shown in Fig.3.
The playback / recording & eraser head should also
be reassembled similarly to step 1 to 4 above.
1.
2.
3.
4.
5.
Reassembling the playback / recording &
eraser head (See Fig.3)

UX-T770R
1-13
Belt
Main motor
assembly
Head amplifier &
mechanism control
board
Flexible board
4pin parallel wire
Main
motor
assembly
Fig. 4
Fig. 4a
Main motor
assembly
Capstan belt
Motor
pulley
Fig. 6
Main motor
assembly
Flywheel
Motor pulleyCapstan belt
Fig. 5
Mechanism motor
assembly
Motor
pulley
Capstan
belt
CN32
CN31
A
A
A
B
B
Remove the cassette mechanism assembly.
After turning over th cassette mechanism assembly,
remove the three screws Aretaining the head
amplifier & mechanism control board.
Disconnect the connector CN32 on the board
including the connector CN 1 on the reel pulse P.C.
board.
When necessary, remove the 4 pin parallel wire
soldered to the main motor.
1.
2.
3.
4.
Removing the head amplifier & mechanism
control board (See Fig. 4)
Remove the two screws Bretaining the main motor
assembly (See Fig.4 and 4a).
While raising the main motor, remove the capstan
belt from the motor pulley (See Fig.4a).
1.
2.
Removing the main motor assembly
Be sure to handle the capstan belt so
carefully that this belt will not be stained
by grease and other foreign matter.
Moreover, this belt should be hanged
while referring to the capstan belt
hanging method in Fig. 5 and 6.
CAUTION:

UX-T770R
1-14
Flywheel R Flywheel L
Capstan shaft R Capstan shaft L
Slit
washer 1 Slit washer 1
Fig. 8
Flywheel R Flywheel L
Fig. 9
Reel pulse board
Fig. 7
Solenoid
a b c d e
fg
Remove the head amplifier & mechanism control P.C.
board.
Remove the main motor assembly.
After turning over the cassette mechanism, remove
the two slit washers 1 and fixing the capstan shafts R
and L, and pull out the flywheel R and L respectively
from behind the cassette mechanism.
1.
2.
3.
Removing the flywheel (See Fig. 7 and 8)
Remove the five pawls a to ereattaining the reel
pulse board.
From the surface of the reel pulse board parts,
remove the two pawls f and gretaining the solenoid.
1.
2.
Removing the reel pulse P.C. board and
solenoid (See Fig. 9)

UX-T770R
1-15
Shield
CD mechanism board
Fig. 1
Fig. 2
CD mechanism
BB
BB
AA
A
ACN601
CN602
P011
CD servo
control board
<CD Player Unit Section>
Remove the rear panel.
Remove the left and right side panels.
Remove the CD player unit.
After turning back the CD player unit, remove the
four screws Aretaining the CD servo control board
and shield.
From the connector CN601 on the CD servo control
board, disconnect the card wire outgoing from the
CD mechanism.
From the connector P011 on the CD mechanism P.C.
board, disconnect the connector wire outgoing from
the connector CN602 on the CD servo control board.
Remove the four screws Bretaining the CD
mechanism.
While sliding the CD mechanism in the arrow
direction, take turn table out so carefully that it does
not come into contact with the chassis.
1.
2.
3.
4.
5.
6.
7.
8.
Removing the CD mechanism and CD
servo control P.C. board (See Fig. 1 and 2)

UX-T770R
1-16
Adjustment method
Measurement instruments required for
adjustment
1. Low frequency oscillator
This oscillator should have a capacity to output
0dBs to 600 at an oscillation frequency of
50Hz-20kHz.
2. Attenuator impedance : 600
3. Electronic voltmeter
4. Distortion meter
5. Frequency counter
6.Wow & flutter meter
7.Test tape
VT712 :Tape speed and running unevenness
(3kHz)
VT724 : Reference level (1kHz)
TMT7036 : Head angle (10kHz), playback
frequency
characteristics (1kHz) and dubbing
frequency
characteristics (63, 1 and 10kHz)
Because of frequency -mixed tape with 63, 1, 10 and
14kHz (250nWb/m - 24dB), use this tape together
with a filter.
8. Blank tape
TYPE : AC-225
TYPE : AC-514
9.Torque gauge : For play and back tension
FWD(TW2111A), REV(TW2121a) and
FF/REW(TW2231A)
Measurement conditions
Power supply voltage
Reference output
Reference frequency and
input level
Input for confirming recording and
playback characteristics
Measurement output terminal
Load resistance
Radio Input signal
AM frequency 400Hz
AM modulation 30%
FM frequency 400Hz
FM frequency deviation 22.5kHz
Tuner section
Voltage applied to tuner +B : DC5.7V
VT : DC 12V
Reference measurement 26.1mV(0.28V)/4
output
Input positions AM : Standard loop antenna
FM :TP1 (hot) and TP2 (GND)
Standard measurement position of volume
Bass Off
Active hoper bass pro Off
Up and down adjustment of volume VOL : 23
Precautions for measurement
1. Apply 30pF and 33k to the IF sweeper output
side and 0.082 F and 100k in series to the
sweeper input side.
2.The IF sweeper output level should be made as
low as possible within the adjustable range.
3. Since the IF sweeper is a fixed device, there is no
need to adjust this sweeper.
4. Since a ceramic oscillator is used, there is no need
to perform any MIX adjustment.
5. Since a fixed coil is used, there is no need to adjust
the FM tracking.
6.The input and output earth systems are separated.
In case of simultaneously measuring the voltage in
both of the input and output systems with an
electronic voltmeter for two channels, therefore, the
earth should be connected particularly carefully.
7. In the case of BTL connection amp., the minus
terminal of speaker is not for earthing.Therefore, be
sure not to connect any other earth terminal to this
terminal. This system is of an BTL system.
8. For connecting a dummy resistor when measuring
the output, use the wire with a greater code size.
9.Whenever any mixed tape is used, use the band
pass filter (DV-12).
AC230V (50Hz)
Speaker : 0.775V/4
Headphone : 0.245V/32
AUX : -28dBs
Speaker J3002
4
1kHz, AUX : -8dBs

UX-T770R
1-17
VR37
L031
VR31
VR32
Bias TP
Playback/Recording &
eraser head
Playback/Recording &
eraser head
<<Arrangement of adjusting positions>>
Cassette mechanism section
Front panel assembly section
Cassette mechanism section (Bottom side)
Head azimuth
adjusting screw
(Forward side)
Head azimuth
adjusting screw
(Reverse side)
Head azimuth
adjusting screw
(Forward side)
Head azimuth
adjusting screw
(Reverse side)

UX-T770R
1-18
Tape Recorder Section
Reference Values for Confirmation Items
Items
Items
Measurement
conditions
Measurement
conditions
Measurement method
Measurement method
Standard
Values
Standard
Values
Adjusting
positions
Adjusting
positions
Confirmation
of head angle
Confirmation
of tape speed
Test tape
:TMT7036 (10kHz)
Measurement output
terminal
: Speaker terminal
Speaker R
(Load resistance: 4 )
: Headphone terminal
1 Playback the test tape TMT7036 (10kHz)
2 With the recording & playback mechanism,
adjust the head azimuth screw so that the
forward and reverse output levels become
maximum. After adjustment, lock the head
azimuth at least by half turn.
3 In either case, this adjustment should be
performed in both the forward and reverse
directions with the head azimuth screw.
Maximum
output
Tape speed
of deck
: 3,010Hz
15Hz
Adjust the head
azimuth screw
only when the
head has been
changed.
Test tape
:VT712 (3kHz) or
TMT7036 (3kHz)
Measurement output
terminal
: Headphone terminal
When the test tape VT712 (3kHz) has been
played back with the recording and playback
mechanism at the beginning of forward
winding, the frequency counter reading of the
difference between both of the mechanism
should be 6.0Hz or less.
Adjust VR37 so that the frequency counter
reading becomes 3,010Hz 15Hz when
playing back the test tape VT712 (3kHz) with
playback and recording mechanism after
ending forward winding of the tape.
VR37
Difference
between the
forward and
reverse speed
Test tape
:VT712 (3kHz) or
TMT7036 (3kHz)
Measurement output
terminal
: Speaker terminal
Speaker R
(Load resistance: 4 )
Measurement output
terminal
: Headphone
6.0Hz or
less Head azimuth screw
(See Fig. 34)
Wow & flutter Test tape
:VT712 (3kHz) or
TMT7036 (3kHz)
Measurement output
terminal
: Headphone terminal
When the test tape VT712 (3kHz) has been
played back with the recording and playback
mechanism at the beginning of forward
winding, the frequency counter reading of
wow & flutter should be 0.25% or less
(WRMS).
0.25% or
less
(WRMS)

UX-T770R
1-19
Electrical Performance
ReferenceValues for Electrical Function Confirmation Items
Items
Items
Measurement
conditions
Measurement
conditions
Measurement method
Measurement method
Standard
Values
Standard
Values
Adjusting
positions
Adjusting
positions
Adjustment of
recording and
playback
frequency
characteristics
Adjustment of
recording bias
current
(Reference
Value)
Reference frequency
: 1kHz and 10kHz
(REF.: -20dB)
Test tape
: AC-514 to TYPE
Measurement input
terminal
: OSC IN
Mode: Forward or
reverse mode
Recording mode
Test tape
: AC-514 to TYPE
and AC-225 to
TYPE
Measurement output
terminal
: Both recording and
headphone terminals
1 With the recording and playback
mechanism, load the test tapes (AC-514 to
TYPE and AC-225 to TYPE ), and set
the mechanism to the recording and
pausing condition in advance.
2 After connecting 100 in series to the
recorder head, measure the bias current
with a valve voltmeter at both of the
terminals.
3 After resetting the [PAUSE] mode, start
recording. At this time, adjustVR31 for Lch
and VR32 for Rch so that the recording
bias current values become 4.0 A (TYPE
) and 4.20 A (TYPE ).
1 With the recording and playback
mechanism, load the test tapes (AC-514 to
TYPE ), and set the mechanism to the
recording and pausing condition in
advance.
2 While repetitively inputting the reference
frequency signal of 1kHz and 10kHz from
OSC IN, record and playback the rape.
3 While recording and playback the test tape
in TYPE , adjust VR31 for Lch and VR32
for Rch so that the output deviation
between 1kHz and 10kHz becomes
-1dB 2dB.
1 While recording and playback mechanism,
load the test tapes (AC-514 to TYPE
and AC-225 to TYPE ), and set the
mechanism to the recording and pausing
conditions in advance.
2 After setting to the recording conditions,
connect 1W in series to the eraser head on
the recording and playback mechanism
side, and measure the eraser current from
both of the eraser terminals.
1 While changing over to and from BIAS 1
and 2, confirm that the frequency is
changed.
2 With the recording and playback
mechanism, load the test tape.
(AC-514 to TYPE ), and set the
mechanism to the recording and pausing
condition in advance.
3 Confirm that the BIASTP frequency on the
P.C. board is 100kHz 6kHz.
Recording
bias
frequency
Forward or reverse
Test tape
:TYPE (AC-514)
Measurement
terminal : BIAS TP on
P.C. board
100 kHz
6 kHz
Eraser
current
(Reference
value)
Forward or reverse
Recording mode
Test tape
: AC-514 to TYPE
and AC-225 to
TYPE
Measurement
terminal : Both of the
eraser head terminals
TYPE
: 120 mA
TYPE
: 75 mA
AC-225
: 4.20 A
AC-514
: 4.0 A
L ch
:VR31
R ch
:VR32
Output
deviation
between
1kHz and
10kHz
: -1dB 2dB
L ch
:VR31
R ch
:VR32

UX-T770R
1-20
Flow of functional operation until TOC read
Slider turns REST
SW ON.
Automatic tuning
of TE offset
Laser ON
Detection of disc
Automatic measurement of
Focus A-curve amplitude
Automatic tuning of
Focus offset
Disc is rotated
Focus servo ON
(Tracking servo ON)
Automatic tuning of
Tracking error balance
Automatic measurement of
Tracking error amplitude
Automatic tuning of
Focus error balance
Disc to be
braked to stop
Tracking
servo
on status
Tracking
servo
off status
Disc status
to rotate TOC reading
finishes
Automatic measurement
of TE amplitude and
automatic tuning of
TE balance 500mv/div
2ms/div Fig.1
Approx.3sec
pin 25 of
IC601(TE)
Approx
1.8V
VREF
Tracking error waveform at TOC reading
Power ON Power Key
Confirm that the Focus error
S-cuve signal at the pin27 of
IC601 is approx.2Vp-p
Confirm that the signal from
pin24 IC603 is 0V as a
accelerated pulse during
approx.400ms.
Confirm the waveform of
the Tracking error signal
at the pin25 of IC601 (R612)
(See fig-1)
Automatic tuning of
Focus error gain
Automatic tuning of
Tracking error gain
TOC reading
Play a disc
Confirm the eys-pattern
at the lead of TP1
Check that the voltage at the pin17
of CN604 is 0V (a moment)?
Check Point
Check that the voltage at the
pin3 of IC601 + side is + 5V?