LG TCC-9420 Service manual

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[CONTENTS]

❍ SECTION 1. SUMMARY

• ESD PRECAUTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2

• ESD PRECAUTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3

• SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4

❍ SECTION 2. ELECTRICAL

• ADJUSTMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1

• INTERNAL BLOCK DIAGRAM of ICs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-7

• WIRING DIAGRAM(DECK MECHANISM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-15

• BLOCK DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-17

• SCHEMATIC DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-19

• PRINTED CIRCUIT DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-21

❍ SECTION 3. CABINET MAIN CHASSIS & MECHANISM

• EXPLODED VIEW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1

❍ SECTION 4. REPLACEMENT PARTS LIST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1

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SECTION 1. SUMMARY

❏ SERVICING PRECAUTIONS

1. Always disconnect the power source before:

1) Removing or reinstalling any component, circuit board, module or any other instrument assembly.

2) Disconnecting or reconnecting any instrument electrical plug or other electrical connection.

3) Connecting a test substitute in parallel with an electrolytic capacitor in the instrument.

CAUTION: A wrong part substitution or incorrect polarity installation of electrolytic capacitors may result in an

explosion hazard.

2. Do not defeat any plug/socket B+ voltage interlocks with which instruments covered by this service manu­al might be equipped.

3. Do not apply power to this instrument and or any of its electrical assemblies unless all solid-state device
heat sinks are correctly installed.

4. Always connect a test instrument’s ground lead to the instrument chassis ground before connecting the
test instrument positive lead. Always remove the test instrument ground lead last.

1) The service precautions are indicated or printed on the cabinet, chassis or components. When servicing, follow
the printed or indicated service precautions and service materials.

2) The Components used in the unit have a specified conflammability and dielectric strength. When replacing any
components, use components which have the same ratings. Components marked in the circuit diagram are
important for safety or for the characteristics of the unit. Always replace with the exact components.

3) An insulation tube or tape is sometimes used and some components are raised above the printed writing board
for safety. The internal wiring is sometimes clamped to prevent contact with heating components. Install them
as they were.

4) After servicing always check that the removed screws, components and wiring have been installed correctly
and that the portion around the service part has not been damaged. Further check the insulation between the
blades of attachment plug and accessible conductive parts.

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❏ ESD PRECAUTIONS

Some semiconductor (solid state) devices can be damaged easily by static electricity. Such omponents commonly
are called Electrostatically Sensitive Devices (ESD). Examples of typical ESD devices are integrated circuits and
some field-effect transistors and semiconductor chip components. The following techniques should be used to
help reduce the incidence of component damage caused by static electricity.

1) Immediately before handling any semiconductor component or semiconductor-equipped assembly, drain off any
electrostatic charge on your body by touching a known earth ground. Alternatively, obtain and wear a commer­cially available discharging wrist strap device, which should be removed for potential shock reasons prior to
applying power to the unit under test.

2) After removing an electrical assembly equipped with ESD devices, place the assembly on a conductive surface
such as aluminum foil, to prevent electrostatic charge buildup or exposure of the assembly.

3) Use only a grounded-tip soldering iron to solder or unsolder ESD devices.

4) Use only an anti-static solder removal device. Some solder removal devices not classified as “anti-static” can
generate electrical charges sufficient to damage ESD devices.

5) Do not use freon-propelled chemicals. These can generate electrical charges sufficient to damage ESD
devices.

6) Do not remove a replacement ESD device from its protective package until immediately before you are ready to
install it. (Most replacement ESD devices are packaged with leads electrically shorted together by conductive
foam, aluminum foil or comparable conductive material).

7) Immediately before removing the protective material from the leads of a replacement ESD device, touch the
protective material to the chassis or circuit assembly into which the device will be installed.

CAUTION: Be sure no power is applied to the chassis or circuit, and observe all other safety precautions.

8) Minimize bodily motions when handling unpackaged replacement ESD devices. (Otherwise harmless motion
such as the brushing together of your clothes fabric or the lifting of your foot from a carpeted floor can generate
static electricity sufficient to damage an ESD device).

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❏ SPECIFICATIONS

1. GENERAL

Power requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .DC12V~15V

Ground system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Negative

Dimensions(W x H x D) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182 x 53 x 160mm

Weight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Net: 1.5kg

2. RADIO SECTION

FM AM(MW) . . . . . . . . . . . . .LW(Optional)

Frequency range . . . . . . . . . . . . . .65.0~74.0MHz(Optional), 522~1,620kHz . . . . . . . . .144~281kHz

. . . . . . . . . . . . . . . . . . . . . . . . . . . .87.5~108MHz (Optional:530~1,710kHz/

520~1,620kHz)

Intermediate frequency . . . . . . . . . .10.7MHz 450kHz . . . . . . . . . . . . . . . . . .450kHz

Usable sensitivity . . . . . . . . . . . . . .10dBµV 28dBµV . . . . . . . . . . . . . . . . . .35dBµV

Signal to noise ratio . . . . . . . . . . . .60dB 50dB . . . . . . . . . . . . . . . . . . . . . .50dB

3. TAPE SECTION

Tape type . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 track 2channel system

Tape speed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.75cm/sec

Wow and flutter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.15%(WRMS)

Signal to noise ratio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50dB

4. AUDIO SECTION

Maximum output power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50W x 4

Frequency response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40Hz to 14,000Hz

Speaker impedance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4Ω x 4 or 8Ω x 4

Signal to noise ratio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60dB

NOTE: The design and specifications are subject to change without notice in the sourse of product

improvement.

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SECTION 2. ELECTRICAL

❏ ADJUSTMENTS

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2. FM Adjustment

(1) The impedance of FM antenna terminal is 75Ω.

Therefore, connect coaxial cable (3C-2V etc.) between FM SG and antenna terminal when wiring.

(2) There are two kind in indication of FM SG output attenuator.

1) Attenuator with Marking of 75Ω open...open indication type

2) Attenuator with marking of 75Ω load or close...load or close indication type.

(3) FM SG output level in this FM adjustment are described as open indication type. The left table shows relations

among FM SG attenuator indication(dB), available power ratio(dBf) and antenna terminal voltage(dB/µV) in each
indication type.

Notes:

1. BAND Switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . FM

2. BALANCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Center

3. TREBLE/BASS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Center

4. Connect as shown in figure 3.

5. Refer to figure 1~2 for Adjustment Points.

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Item FM SSG Attenuator Available Antenna

Type Indication Power Ratio Terminal Voltage

Open indication type

0dB 5.2dBf 6dB/µV

60dB 65.2dBf 66dB/µV
Load or close 0dB 11.2dBf 12dB/µV
indication type 54dB 65.2dBf 66dB/µV

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