Jvc CAMX 55 MBK Service Manual

Page 1

JVC

ERVICE

MANUAL

CA-MX

(UNIT NO. XT-MX55M BK)

55MBK

* For Instruction manual, please Iefe

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* DX-MX55MBK is needed (for power supply etc.) when servicing.

Contents

Safety Precaution ------------------------------------------- 1-2 Initial Operation of Mechanism -------------------------- 1-22

Important for Laser Products ., . 1-3 Operation Check by each switch ------------------------- 1-24

Description of Major LSIs ,. 1-4 Flow of Functional

Internal Block Diagram of the Other le-~ -|-l4 Operation Unit TOC is Read ------------------ 1-25

Internal Wiring of the FL Display Tube ----------------- 1-15 Troubleshooting ------------------------------------------------- 1~26

Disassembly Procedures »»»»»»»»»»»»» , rrrrrrr 1717 Block Diagram ------------------------------------------ 1-31

FM/AM Tuner Alignment Procedures---- 11-19 Schematic Diagrams »- --|nsertion

ClockGenerator Frequency Adjustment-r --|-19 Printed Circuit Board ----- v-Insertion

CD Adjustment Procedures ------------------------------- 1-20 Exploded View of Assemblies and

Maintenance of Laser Pickup-- -- 1-21 Application Points for Grease v -- -|nsertion

Replacement of Laser Pickup-- --1-21 Parts List-- insertion
No.20344

Mar.1992

Page 2

XT-MX55MBK

- Safety Precautions

1. The 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 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 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 repalcement 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.

S. 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,
contorl 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.

0 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,particularily
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.).

0 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 1,5003 10 W
resistor paralleled by a 0.15 #F AC-type capacitor between an exposed metal part and a
known good earth ground. AC VOLWETER

Measure the AC voltage across the resistor E (Having 1000
with the AC voltmeter. ohms/volts, . . _
Move the resistor connection to Each exposed c or more sen51tIVlty,)
metal part, particularly any exposed metal part
having a return path to the chassis, and 015,; ACTYPE
meausre the AC voltage across the resistor. -ll- Place this
Now, reverse the plug in the AC outlet and probe on
repeat each measurement. Any voltage iSOOGfOW each exposed
measured must not exceed 0.7SVAC (r.m.s.). metal PM
This corresponds to 0.5 mA AC (r.m.s.). Good earth ground

- 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.

l*2(Nu20344)

Page 30

XT-MXSSMBK

Spindle servo circuit section

Is the pin1 of ICBOi +1OV?

Is the pinS of IC801 -10V? N0 Check the power
is the pins of ICBOZ +12v7 supply circuit.
is the pin4 of lCBOZ -12VI
YES
Does the spindle .
motor stop when NO _ NO icsm and peripheral
the player is m the Is pin7 of [€802 + 5V? Corfnponents
stop mode? de ective.
YES
YES
is pin53,pin54 of ICAOl N0 Check IC802 and its
4. 5V? Vicmity,
YES
IC401 or IC901 are
faulty.
. Is more than +6V
5 pin8 0f 15801 +5V7 NO present at pin7 of YES Check lCBOl
ICBOZ?
Does the dgsc bfigin
rotating w an: e
play button is NO YES NO
pressed?
Check the spindle NO
YES motor and its Is pin53 of lCAOl +5V? Check IC401 or
connections. IC901.
YES
Check ICBOZ and its
vicinity.
Does thehspindle motor NO I b t 6V NO '5 more than 6V
sto at t e moment sa ou - present . ' YES
thn the Stop Button at pin8 of ICBOl? Egg? at 0'717 0f Check IC801
is pressed? 02-
YES YES NO
Check the spindle Does the voltage level at NO
0K motor and ItS pmsaoflCaOl become Check IC401 or
_ connections. +5then the setis IC901,
stopped 7
YES

Check lC802 and its
vicinity.

l 30 (N020344)