JVC JX-S555 User manual

SERVICE MANUAL
AV SELECTOR
No.70251
Mar. 2001
COPYRIGHT 2001 VICTOR COMPANY OF JAPAN, LTD.
Printed in Japan
0103(S)
VICTOR COMPANY OF JAPAN, LIMITED
COMMUNICATION NETWORK BUSINESS UNIT, 1644, SHIMOTSURUMA, YAMATO-SHI, KANAGAWA-KEN, 242-8514, JAPAN
JX-S555 (J)
No.70251
JX-S555(J)JX-S555(J)
JX-S555(J) No. 70251
Contents
Safety Precautions ............................... 2
Main Parts Locations ............................ 3
Disassembly of Parts ............................ 4
Connection Diagram ............................. 6
Circuit Description ................................ 7
Adjustments ......................................... 11
Position of ICs and Adjustment Points ....... 12
Servicing Guidelines ............................ 13
Block View Inside IC ............................. 17
Design and specifications are subject to change without notice.

JX-S555(J)
2 (No. 70251)
Safety Precautions
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 eachexposed 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.).
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.
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

(No. 70251) 3
JX-S555(J)
Main Parts Locations
AUDIO 2 boardAUDIO 1 board
Front 1 board
Bottom chassis
Front panel ass'yFront 2 board
Rear panel
MAIN board
Jack board
Top cover

JX-S555(J)
4 (No. 70251)
Disassembly of Parts
2
17
6
11
18
17
17
5
14
14
16
22
9
8
15
21
22
20
13
19
12
7
4
3
4
1
15

(No. 70251) 5
JX-S555(J)
Note : For the positions of the connectors, see the connection
diagram (page 6).
Removing the top cover 11
11
1
1. Remove the two screws 3retaining the top cover 1from the
rear panel 2, then remove the four screws 4retaining the
top cover from the side panels.
2. Slightly open out the bottoms of the side skirts Iof the top
cover 1as shown in the figure, then pull the top cover straight
upward II . Do not remove the top cover by pulling it up in an
oblique direction.
Removing the Audio 1 Board 55
55
5and Audio 2
Board 66
66
6
1. Remove the top cover 1.
2. From the rear panel 2, remove the six screws 7retaining the Audio 1 board 5and the six screws 7retaining the
Audio 2 board 6.
3. Gently remove the Audio 1 board 5and then unplug the connectors CN809 and CN810 from it.
4. Gently remove the Audio 2 board 6and then unplug the connectors CN807 and CN808 from it.
Removing the Main Board BB
BB
B
1. Remove the top cover 1, then the Audio 1 board 5and finally the Audio 2 board 6.
2. From the rear panel 2, remove the nineteen screws Cretaining the Main board B.
3. Unplug the connectors CN1, CN3, CN804 and CN811 (and the wire from the Front Panel Assembly D)on the Main
board B.
4. Unplug the connector CN901 (in the power supply circuit) on the Main board B.
5. Remove the two clamping screws Eon the Main board B.
6. Disengage the three claws of the locking card spacer Fon the Main board B, then remove the Main board by lifting
it in an oblique direction.
Removing the Rear Panel 22
22
2
1. Remove the top cover 1.
2. Unplug the connector CN901 (in the power supply circuit) on the Main board B.
3. Remove the twelve screws 7retaining the Audio 1 board 5and the Audio 2 board 6, then remove the nineteen screws
CretainingtheMainboardB.
4. Remove the three screws Hretaining the bottom chassis Gand the rear panel 2.
5. Gently remove the rear panel 2.
(Take care of the AC power cord Iconnected to the rear panel 2.)
Removing the Front Panel Assembly DD
DD
D
1. Remove the top cover 1.
2. Remove the three retaining screws Jfrom the bottom of the Front Panel Assembly D.
3. Disengage the fittings between the side panels of the Front Panel Assembly Dwith the bottom chassis G, then
gently pull out the Front Panel Assembly Dfrom the bottom chassis Gtoward the front.
4. Unplug the connectors CN1, CN3, CN804 and CN811 from the Main board B.
5. Remove the Front Panel Assembly D.
Removing the Front 1 Board KK
KK
K, Front 2 Board LL
LL
Land Jack Board 88
88
8
1. Remove the top cover 1and the Front Panel Assembly D.
2. Remove the two screws Mretaining the Front 1 board K, five screws Mretaining the Front 2 board Land the two screws
9retaining the Jack board 8.
3. Remove the Front 1 board K, the Front 2 board Land the Jack board 8.
II
I
I

JX-S555(J)
6 (No. 70251)
Connection Diagram
CN702 CN703 CN101
CN701
CN3
CN804
CN806 CN805
CN807CN808 CN810 CN809
CN813 CN812
CN811
CN901
CN1
AUDIO 2 board
Rear
AUDIO 1 board
MAIN board
Front 1 board Front 2 board Jack board
Front

(No. 70251) 7
JX-S555(J)
Circuit Description
1. IC2 (µPD780021ACWW01)
The µPD780021ACWW01 is a 64-pin, 8-bit single-chip microcomputer with an 8K-byte ROM and 512-byte RAM.
Pin Name
P40/AD0
P41/AD1
P42/AD2
P43/AD3
P44/AD4
P45/AD5
P46/AD6
P47/AD7
P50/A8
P51/A9
P52/A10
P53/A11
P54/A12
P55/A13
P56/A14
P57/A15
Vss0
VDD0
P30
P31
Pin No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Function
Key scan inputs.
Key scan outputs.
Scan signal outputs for LED lighting.
Dubbing lock ON/OFF. H = ON. L = OFF.
Scan signal outputs for LED lighting.
CH1 INHIBIT ON/OFF. H = ON. L = OFF.
Not used.
Not used.
Not used.
Port grounding potential.
Port positive potential.
CH2 INHIBIT ON/OFF. H = ON. L = OFF.
CH3 INHIBIT ON/OFF. H = ON. L = OFF.
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
—
I
I/O
I/O
I/O

JX-S555(J)
8 (No. 70251)
P32
P33
P34
P35
P36
P20/SI30
P21/SO30
P22/SCK30
P23/RxD0
P24/TxD0
P25/ASCK0
V
DD1
AVss
P17/AN17
P16/AN16
P15/AN15
P14/AN14
P13/AN13
P12/AN12
P11/AN11
P10/AN10
AV
REF
AV DD
RESET
XT2
XT1
IC
X2
X1
Vss
1
P00/INTP0
P01/INTP1
P02/INTP2
P03/INTP3/ADTRT
P70/T100/TO0
P71/TI01
P72/TI50/TO50
P73/TI51/TO51
P74/PCL
P75/BUZ
P64/RD
P65/WR
P66/WAIT
P67/ASTB
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
I
2
C path Data signal.
I
2
C path Clock signal
Not used.
Not used.
Not used.
Not used.
Not used.
Not used.
Not used.
Not used.
Not used.
Positive potential (except for the port).
AD converter grounding potential.
Not used.
Not used.
Not used.
Not used.
Not used.
Not used.
CH5 S1/S2 signal input.
Not used.
A/D converter reference voltage input.
Analog power supply for A/D converter
System reset input.
Sub-system clock oscillation.
Internally connected. To be connected to VSS0 or VSS1.
X'tal oscillator connection terminals for Main
system clock oscillation.
Grounding potential (except for the port).
CH3 D4 plug insertion detection.
CH4 D4 plug insertion detection.
CH5 D4 plug insertion detection.
Not used.
Remote control light signal input.
Component video switching signal output.
Component video switching signal output.
Main unit ON/OFF. H = OFF. L = ON.
S1/S2 signal inputs.
Component video switching signal output.
CH5 monitor signal output.
Main unit ON/OFF. H = OFF. L = ON.
Power switch detection.
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I
—
I
I
I
I
I
I
I
I
I
I
I
—
I
—
—
I
I
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
Pin Name Pin No. Function
I/O

(No. 70251) 9
JX-S555(J)
2. M101, M102 (J46729-002)
•Comb filter module
BufferVIDEO-IN Matrix
BPF
1H-GDL
Buffer
Buffer
Y-OUT
C-OUT
Delay
Line

JX-S555(J)
10 (No. 70251)
3. IC101 (CXA2079Q)
The CXA2079Q is an AV switcher IC with 5 video inputs, 2 video outputs, 5 stereo audio inputs and 2 stereo audio outputs,
featuring the I2C bus compatibility for TV. Among the 5 video inputs, 4 inputs are compatible with the S2 and S-Video
standards.
The outputs (each audio output uses a pair of lines for the L and R channels) can be selected independently by the control
through the I2C bus. However, the second video and audio outputs are always based on the same video and audio input
system.

(No. 70251) 11
JX-S555(J)
Adjustments
Instruments required for adjustments
1. Oscilloscope
2.TV signal generator (NTSC)
Connection
NTSC
color bar JX-S555
1CH
V input
2CH
C outputs
Oscillo
scope
1
2
Test Point
Adjustment Point
2CH C output
MONITOR OUT
C output
Condition ConditionName
C output level
C output level
VR101
VR102
Apply color bar signal to
1CH video input (V).
Apply color bar signal to
1CH video input (V).
Adjust VR101 so that the C output level at 2CH is
0.642 0.02 Vp-p.
Adjust VR102 so that the C output level at
MONITOR OUT is 0.642 0.02 Vp-p.

JX-S555(J)
12 (No. 70251)
MAIN board
UPD780021ACW-W01
IC2
74HC04AP
IC3
NJM
4580D
IC806
NJM
4580D
IC802
74HC4066AP
IC108
74HC4066AP
IC107
74HC4066AP
IC106
74HC4052AP
IC402
74HC4052AP
IC401
74HC4052AP
IC808
74HC4052AP
IC809
74HC126AP
IC403
NJM
4580D
IC801
NJM
4580D
IC807
NJM
4580D
IC805
NJM
4580D
IC804
NJM
4580D
IC803
74HC4066AP
IC102
74HC4066AP
IC104
74HC4066AP
IC103
J46729-002
M102
J46729-002
M101
IC101
VR102 VR101
CXA2079Q
Position of ICs and Adjustment Points

(No. 70251) 13
JX-S555(J)
Servicing Guidelines
1. Reference input signals
Video signals
V →Full-field color bar (white 100%), 1.0 Vp-p
Y →1.0 Vp-p (with sync)
C →Burst level 0.286 Vp-p, chroma only
Audio signal
1 kHz, -10 dBV sine wave
2. YES →Normal
NO →The normal voltage and waveform are not output.
1. Power cannot be
turned ON.
2. Display LED
lighting failure.
C903: Across +/- leads 1 Approx. 164 V DC NO
YES
Check power cord and C901.
If the fuse is blown, check Q901,
T901, D901 and their surroundings.
Go to check 2 .
D906: Cathode
D907: Anode
2 +9.5 V DC
–9.8 V DC
NO
YES
NO R Check voltage at IC902 and
surroundings.PC901 and IC902
may be defective.
Go to check 3 .
Q904: Emitter,
Q905: Emitter,
Q906: Emitter,
IC904: Pin 2
3 –6 V DC
+6 V DC
+5 V DC
+9 V DC
NO
YES
IC901, IC903, IC904 or Q904 to
Q906 defective.
Check CN1,. CN3 and wires.
CN3: Pins 3 to 7 4 0 or +5 V DC NO
YES
IC2 defective.
Q701 to Q706 or wire is defective.
3. Switch operation
failure.
CN3: Pins 8 to 14 0 or +5 V DC NO
YES
IC2 defective.
CN701, tack switch or wire defective.
5
4. S/V switching
failure
IC101: Pins 7, 14, 21 and 28 0 V when S-Video plug is inserted.
+5 V when S-Video plug is not
inserted.
NO
YES
PJ107 to PJ110 defective.
Check IC101 and the surroundings.
6
5. Remote control
malfunction
IC2: Pin 55 + 5 V DC at remote control
code (See TM.)
NO
YES
IC701, CN1, CN702 or wire defective.
IC2 defective.
7
6.
The composite
video inputs at
CH1 and CH2
are not displayed.
A
Q135: Emitter NO
YES
Go to check B .
Check Q152, Q161, Q170 and
their surroundings.
7. The composite
video inputs at
CH1 and CH2
are not output at
the Monitor
output.
Q129: Emitter NO
YES
Go to check 9 .
Check IC106, output buffer and their
surroundings.
Q107: emitter NO
YES
Check IC101 and surroundings.
Check IC103 and their surroundings.
8
9
Symptom Check Points Normal Voltage/Waveform Check Results and Failures
2.0 Vp-p
Q115: Emitter NO
YES
Check IC101 and surroundings.
Check IC103 and their surroundings.
B
2.0 Vp-p
2.0 Vp-p
2.0 Vp-p

JX-S555(J)
14 (No. 70251)
8. The S-Video
inputs at CH1 to
CH4 are not
displayed.
(Y) Q131: Emitter
(C) Q133: Emitter
C (Y)
(C)
(Y)
(C)
NO
YES
Go to check D .
Check IC107, IC108, output buffer
and their surroundings.
(Y) Q108: Emitter
(C) Q109: Emitter
D NO
YES
Check IC101 and surroundings.
Check IC102, IC104 and their
surroundings.
Symptom Check Results and Failures
(Y) Q110: Emitter
(C) Q111: Emitter
NO
YES
Check IC101 and surroundings.
Check IC102, IC104 and their
surroundings.
F
10. The S-Video
input at CH5 is
not displayed.
(Y) Q104: Emitter
(C) Q102: Emitter
NO
YES
Check Q101 to Q104, Q119, Q120
and their surroundings.
Go to check C .
G
2.0 Vp-p
1.28 Vp-p
(Y)
(C)
2.0 Vp-p
1.28 Vp-p
(Y)
(C)
2.0 Vp-p
1.28 Vp-p
9. The S-Video
inputs at CH1 to
CH4 are not
output at the
Monitor output.
(Y) Q137: Emitter
(C) Q139: Emitter
E (Y)
(C)
NO
YES
Go to check F .
Check output buffer and
surroundings.
2.0 Vp-p
1.28 Vp-p
2.0 Vp-p
1.28 Vp-p
Check Points Normal Voltage/Waveform

(No. 70251) 15
JX-S555(J)
11. The S-Video
input at CH5 is
not output at the
Monitor output.
(Y) Q104: Emitter
(C) Q102: Emitter
H (Y)
(C)
(Y)
(C)
NO
YES
Check Q101 to Q104, Q119, Q120
and their surroundings.
Go to check E .
(Y) Q114: Emitter
(C) Q113: Emitter
I NO
YES
Go to check J .
Check IC101 and surroundings.
Symptom Check Results and Failures
12. Malfunction in
Y/C separation.
2.0 Vp-p
1.28 Vp-p
2.0 Vp-p
1.28 Vp-p
(Y)
(C)
(Y) M101: Pin 5
(C) M101: Pin 3
J NO
YES
M101 defective.
Check Q112 to Q114, Q173, Q174
and their surroundings.
1.0 Vp-p
0.64 Vp-p
(Y)
(C)
(Y) Q118: Emitter
(C) Q117: Emitter
K NO
YES
Go to check L .
Check IC101 and surroundings.
13. Malfunction in
Y/C separation
for monitor
output.
2.0 Vp-p
1.28 Vp-p
(Y)
(C)
(Y) M102: Pin 5
(C) M102: Pin 3
L NO
YES
M101 defective.
Check Q116, Q117, Q175, Q176
and their surroundings.
1.0 Vp-p
0.64 Vp-p
Check Points Normal Voltage/Waveform

JX-S555(J)
16 (No. 70251)
Symptom Check Results and Failures
16. Component
video signal is
not output.
(Y) Q401: Emitter
(Pb) Q402: Emitter
(Pr) Q403: Emitter
NO
YES
Check IC401, IC402 and their
surroundings.
Check 6 dB amp (Q404 to Q409,
Q413 to Q415), output buffer and
their surroundings.
O
(Y)
(Cb)
(Cr)
1.0 Vp-p
0.7 Vp-p
0.7 Vp-p
–10 dBV
(0.32 Vrms)
17. Audio signals
are not output.
P
(L) IC806: Pins 6 & 7
(R) IC806: Pins 1 & 2
NO
YES
Go to check Q .
Check IC808, IC809 and their
surroundings.
–10 dBV
(0.32 Vrms)
Q
(L) IC801 to IC805: Pins 7
(R) IC801 to IC805: Pins 1
NO
YES
Check IC801 to IC805 and
their surroundings.
Check IC101 and surroundings.
–10 dBV
(0.32 Vrms)
18. Audio signals
are not output
at the Monitor.
R
(L) IC807 pins 6 & 7
(R) IC807 pins 1 & 2
NO
YES
Check IC807 and surroundings.
Check CN806 and wire.
14. Malfunction in
Y/C mixing of
CH1 to CH4
inputs.
Q107: Emitter
(Monitor output: Q115 emitter)
NO
YES
Check IC101 and surroundings.
Check IC103 and their surroundings.
M
2.0 Vp-p
15. Malfunction in
Y/C mixing of
CH5 input.
Q122: Emitter NO
YES
Check Q105, Q106, Q121,
Q122 and their surroundings.
Check IC103 and their surroundings.
N
2.0 Vp-p
Check Points Normal Voltage/Waveform

(No. 70251) 17
JX-S555(J)
Block View Inside IC
IC1 M51957AL [MITSUBISHI]
IC2 uPD780021ACWW01
IC4 HD74HC375FP [HITACHI]
1D
1Q
1Q
G1·2
2Q
2Q
2D
GND
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
1D
C1
(3)
(2)
(5)
(6)
(11)
(10)
(13)
(14)
(1)
(4)
(7)
(9)
(12)
(15)
1D
G1·2
2D
3D
G3·4
4D
1Q
1Q
2Q
2Q
3Q
3Q
4Q
4Q
V CC
4D
4Q
4Q
G3·4
3Q
3Q
3D
(TOP VIEW)
INPUTS
TRUE TABLE
X: Don’t care
D
L
H
X
G
H
H
L
OUTPUTS
Q
L
H
Qn
Q
H
H
Qn LATCH
FUNCTION
C2
2D
3D
C3
C4
4D

JX-S555(J)
18 (No. 70251)
IC101 CXA2079Q IC102-108 TC74HC4066AP [TOSHIBA]
IC801-807 NJM4580D [JRC]

(No. 70251) 19
JX-S555(J)
COMPARATOR
LIMITER B.P.F
MODULATOR
INTEGRATOR
IC401-402, 808-809 TC74HC4052AP
[TOSHIBA]
IC701 GP1U261R [SHARP]
IC901 M5230L [MITSUBISHI]
8
7
6
5
4
3
2
1
M5230L
OUTPUT CONTROL
INPUT (+)
OUTPUT (+)
VOLTAGE ADJUSTMENT
INPUT (-)
OUTPUT (-)
BALANCE ADJUSTMENT
GND
START
CIRCUIT
OVERHEAT
PROTECTOR
OUTPUT
CONTROL
87
REFERENCE
VOLTAGE
GENERATOR
ERROR
AMPLIFIER
INPUT (+)
6OUTPUT (+)
OVER
CURRENT
PROTECTOR
5VOLTAGE ADJUSTMENT
1GND
2BALANCE ADJUSTMENT
3OUTPUT (-)
4INPUT (-)
ERROR
AMPLIFIER
OVER
CURRENT
PROTECTOR

JX-S555(J)
20 (No. 70251)
IC902-903 uPC1093J [NEC]
MARKED
SURFACE
TO-92 PACKAGE
IC904 PQ09RD08 [SHARP]
1 2 3 4
2
21
3
4
3
1
4
DC input (Vin)
DC output (Vout)
GND
Spesific IC
ON/OFF control terminal (Vc)
1A 1
1Y 2
2A 3
2Y 4
3A 5
3Y 6
GND 7
14 Vcc
13 6A
12 6Y
11 5A
10 5Y
94A
84Y
(TOP VIEW)
AY
IC3 TC74HC04AP [TOSHIBA]
1G 1
1A 2
1Y 3
2G 4
2A 5
2Y 6
GND 7
14 Vcc
13 4G
12 4A
11 4Y
10 3G
93A
83Y
(TOP VIEW)
INPUTS OUTPUTS
GA Y
LX Z
HL L
HH H
X : Don't Care
Z : High Impedance
R13
Q10
R14
R15
D1
Q9
R17
R16
R1
Q1
R2 R4
R5
Q4
Q3
Q2 R3
Q8
R8 R7
R6
R10
R12
R9
C1
Q13
Q14
Q12
Q5
Q6
R11
Q7
Q11
(1) INPUT
(2) OUTPUT
(3) COMMON
INPUT
31
2
OUTPUT
COMMON
TA78L005AP 5V
TA78L012AP 12V
Schematic Diagram
IC404 TA78L005AP [TOSHIBA]
IC403 TC74HC126AP [TOSHIBA]