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- 5 -

c. Qulckly move the soldering iron tip to the junction of the

component  lead  and  the  printed  circuit  foil,  and  hold  it
there only until the solder flows onto and around both the
component lead and the foil.

CAUTION: 

Work quickly to avoid overheating the circuit

board printed foil.

d. Closely  inspect  the  solder  area  and  remove  any  excess

or splashed solder with a small wire-bristle brush.

IC Remove/Replacement

Some chassis circuit boards have slotted holes (oblong) through
which  the  IC  leads  are  inserted  and  then  bent  flat  against  the
circuit  foil.  When  holes  are  the  slotted  type,  the  following
technique should be used to remove and replace the IC. When
working  with  boards  using  the  familiar  round  hole,  use  the
standard technique as outlined in parapraphs 5 and 6 above.

Removal

1.  Desolder  and  straighten  each  IC  lead  in  one  operation  by

gently prying up on the lead with the soldering iron tip as the
solder melts.

2.  Draw  away  the  melted  solder  with  an  anti-static  suction-

type  solder  removal  device  (or  with  solder  braid)  before
removing the IC.

Replacement

1.  Carefully insert the replacement IC in the circuit boare.
2.  Carefully  bend  each  IC  lead  against  the  circuit  foil  pad  and

solder it.

3.  Clean the soldered areas with a small wire-bristle brush.

(It is not necessary to reapply acrylic coating to the areas).

"Small-Signal" Discrete Transistor
Removal/Replacement

1.  Remove  the  defective  transistor  by  clipping  its  leads  as

close as possible to the component body.

2.  Bend  into  a  "U"  shape  the  end  of  each  of  three  leads

remaining on the circuit board.

3.  Bend into a "U" shape the replacement transistor leads.
4.  Connect  the  replacement  transistor  leads  to  the

corresponding  leads  extending  from  the  circuit  board  and
crimp the "U" with long nose pliers to insure metal to metal
contact then solder each connection.

Power Output, Transistor Device
Removal/Replacement

1.  Heat and remove all solder from around the transistor leads.
2. Remove the heatsink mounting screw (if so equipped).
3.  Carefully  remove  the  transistor  from  the  heat  sink  of  the

circuit board.

4.  Insert new transistor in the circuit board.
5. Solder each transistor lead, and clip off excess lead.
6.  Replace heatsink.

Diode Removal/Replacement

1.  Remove  defective  diode  by  clipping  its  leads  as  close  as

possible to diode body.

2.  Bend  the  two  remaining  leads  perpendicula  y  to  the  circuit

board.

3.  Observing  diode  polarity,  wrap  each  lead  of  the  new  diode

around the corresponding lead on the circuit board.

4.  Securely crimp each connection and solder it.
5. Inspect (on the circuit board copper side) the solder joints of

the  two  "original"  leads.  If  they  are  not  shiny,  reheat  them
and if necessary, apply additional solder.

Fuse and Conventional Resistor
Removal/Replacement

1.  Clip  each  fuse  or  resistor  lead  at  top  of  the  circuit  board

hollow stake.

2.  Securely crimp the leads of replacement component around

notch at stake top.

3.  Solder the connections.

CAUTION: 

Maintain  original  spacing  between  the  replaced

component  and  adjacent  components  and  the  circuit  board
to prevent excessive component temperatures.

Circuit Board Foil Repair

Excessive heat applied to the copper foil of any printed circuit
board will weaken the adhesive that bonds the foil to the circuit
board  causing  the  foil  to  separate  from  or  "lift-off"  the  board.
The  following  guidelines  and  procedures  should  be  followed
whenever this condition is encountered.

At IC Connections

To repair a defective copper pattern at IC connections use the
following  procedure  to  install  a  jumper  wire  on  the  copper
pattern side of the circuit board. (Use this technique only on IC
connections).

1.  Carefully remove the damaged copper pattern with a sharp

knife.  (Remove  only  as  much  copper  as  absolutely
necessary).

2.  carefully  scratch  away  the  solder  resist  and  acrylic  coating

(if used) from the end of the remaining copper pattern.

3.  Bend a small "U" in one end of a small gauge jumper wire and

carefully crimp it around the IC pin. Solder the IC connection.

4.  Route  the  jumper  wire  along  the  path  of  the  out-away

copper pattern and let it overlap the previously scraped end
of the good copper pattern. Solder the overlapped area and
clip off any excess jumper wire.

At Other Connections

Use  the  following  technique  to  repair  the  defective  copper
pattern  at  connections  other  than  IC  Pins.  This  technique
involoves  the  installation  of  a  jumper  wire  on  the  component
side of the circuit board.

1.  Remove the defective copper pattern with a sharp knife.

Remove  at  least  1/4  inch  of  copper,  to  ensure  that  a
hazardous condition will not exist if the jumper wire opens.

2.  Trace  along  the  copper  pattern  from  both  sides  of  the

pattern  break  and  locate  the  nearest  component  that  is
directly connected to the affected copper pattern.

3.  Connect  insulated  20-gauge  jumper  wire  from  the  lead  of

the nearest component on one side of the pattern break to
the lead of the nearest component on the other side.
Carefully crimp and solder the connections.

CAUTION: 

Be sure the insulated jumper wire is dressed so

the it does not touch components or sharp edges.

Summary of Contents for CT-21Q41KE

Page 1: ...ERVICE MANUAL CAUTION BEFORE SERVICING THE CHASSIS READ THE SAFETY PRECAUTIONS IN THIS MANUAL CHASSIS MC 019A MODEL CT 21Q41KE KEX 42KEX website http biz LGservice com e mail http www LGEservice com techsup html ...

Page 2: ... 3 Servicing Precautions 4 Specifications 6 Description of Controls 7 Disassembly Instructions 10 Adjustment 11 Purity Convergence Adjustment 14 Block Diagram 17 Exploded View 18 Exploded View Parts List 19 Replacement Parts List 20 SVC Sheet ...

Page 3: ...perform an AC leakage current check on the exposed metallic parts of the cabinet such as antennas terminals etc to be sure the set is safe to operate without damage of electrical shock Leakage Current Cold Check Antenna Cold Check With the instrument AC plug removed from AC source connect an electrical jumper across the two AC plug prongs Place the AC switch in the on positioin connect one lead of...

Page 4: ...s are integrated circuits and some fieldeffect transistors and semicounductor chip components The following techniques should be used to help reduce the incidence of component damage caused by static by static electricity 1 Immediately before handling any semiconductor component or semiconductor equipped assembly drain off any electostatic charge on your body by touching a known earth ground Alter...

Page 5: ...the corresponding lead on the circuit board 4 Securely crimp each connection and solder it 5 Inspect on the circuit board copper side the solder joints of the two original leads If they are not shiny reheat them and if necessary apply additional solder Fuse and Conventional Resistor Removal Replacement 1 Clip each fuse or resistor lead at top of the circuit board hollow stake 2 Securely crimp the ...

Page 6: ... On Screen Display EASY MENU Voice coil impedance 8 ohm Sound output 7W 2 MAX Dual Stereo A2 NICAM Option External connection Head Phone Jack A V in 2 PERI Connector Full Scart 1 DVD in External In Output Audio In 0 5Vrms 3dB over 10Kohm Audio Out 0 5Vrms 3dBb below 1Kohm Video In Out 1Vp p 3dB 75ohm DVD In Y 1Vp p 3dB Pb Pr 0 7Vp p 3dB Feature Auto programme Manual programme CSM Color Status Memo...

Page 7: ...s a programme or a menu item switches the set on from standby scans programmes automatically F F G G Volume Up Down adjusts the volume adjusts menu settings OK accepts your selection or displays the current mode 6 Q VIEW returns to the previously viewed programme selects a favorite programme 7 TELETEXT BUTTONS option These buttons are used for teletext For further details see the Teletext section ...

Page 8: ...e used for teletext only TELETEXT models or programme edit Battery installation The remote control handset is powered by two AAA type batteries To load the batteries turn the remote control handset over and open the battery compartment Install two batteries as indicated by the polarity symbols and marked inside the compartment Note To avoid damage from possible battery leakage remove the batteries...

Page 9: ...o out sockets of exter nal equipment to these sockets Note If both the input jacks on the front side panel and back panel have been connected to external equipments simultaneously only the input jacks on the front side panel can be received 10 HEADPHONE SOCKET option Connect the headphone plug to this socket 11 EYE option adjusts picture according to the surrounding conditions Note Do not place an...

Page 10: ...oval 1 Pull out the CPT board from the CPT neck 2 Place the front cabinet on soft material not to mar the front surface or damage control knobs 3 Remove 5 screws securing the picture tube mounting brackets to the front cabinet 4 Carefully separate CPT from the front cabinet PICTURE TUBE HANDLING CAUTION Due to high vacuum and large surface area of picture tube great care must be exercised when han...

Page 11: ... mode 2 Press the Yellow button several times to find OPTION 1 or OPTION 2 3 Input the correspond OPTION data referring to Table below with the numeric buttons 4 Press the OK button to memorize the data Table 1 OPTION 1 Function Table 2 OPTION 2 Function Table 3 OPTION 3 Function ADJUSTMENT 21 FCD 12 FLAT 14 16 CPT 8 15 CPT 10 FLAT 20 21 CPT 12 CDL Data Remark 0 1 0 1 0 1 0 1 0 1 SCART TOP 2 IN 1 ...

Page 12: ...s Channel UP DOWN button for desirous function adjustment 5 Adjust VOL or VOL button in each status of RG BG for X 272 8 Y 288 8 with color analyzer Europe Model X 288 8 Y 295 X 272 8 11 000K 7 Press the OK button to memorize the data Test Point AGC TP C101 Adjust Remote Controller Tuner P N Marker AGC Voltage 6700VPF009G LG Innotek W S TUNER 2 7 0 05V 6700VPF016A DAEWOO W S TUNER 2 7 0 05V Tuner ...

Page 13: ... is in accord with geometric horizontal center of the CPT VA Vertical Amplitude Adjust so that the circle of a digital circle pattern may be located within the effective screen of the CPT SC Vertical S Correction Adjust so that all distance between each horizontal lines are to be the same VS Vertical Shift Adjust so that the horizontal center line of a digital circle pattern is in accord with geom...

Page 14: ...mpletely forward 5 Reconnect the internal degaussing coil 6 Position the beam bender locking rings at the 9 o clock position and the other three pairs of tabs 2 4 and 6 pole magnets at the 12 o clock position 7 Perform the following steps in the order given to prepare the receiver for the purity adjustment procedure a Face the receiver in the magnetic north direction b Externally degauss the recei...

Page 15: ...e internal degaussing coil 9 Turn on the receiver connect a signal generator to the VHF antenna terminal and apply a crosshatch signal Caution During the convergence adjustment procedure be very careful not to disturb the purity adjustment tabs are accidentally move purity should be confirmed before proceeding with the convergence adjustments Note Make sure the focus is set correctly on this instr...

Page 16: ... and blue horizontal lines Fig upper right 17 Temporarily place a rubber wedge at the 5 o clock and 7 o clock positions to hold the horizontal position of the yoke 18 Check the 3 o clock and 9 o clock areas to confirm that the red and blue vertical lines are converged If the lines are not converged slightly offset the horizontal tilt of the yoke move the temporary rubber wedges if necessary to equ...

Page 17: ...7266 97 STEREO Sound Max SOUND AMP TDA7266 97 IC131 5V REG Option Part IIC Bus Line TDA9381 Non TXT Audio Mono TV OUT 28 33 21 22 38 Sound Trap Part Video OUT TV MNT OUT 50 42 51 53 STEREO B01K A13P MONO B01L 10 12 9 5 3 9 8 10 2 6 14V 1 ST BY TRANS 3W Opt SPK L OUT 24 25 47 44 AUDIO AM IN L L Only 30 39 31 40 28 30 14 39 8V From IC844 14 39 39 3 3V Reg 5V From IC842 3 3V 8V From IC844 IC844 8V RE...

Page 18: ... 18 EXPLODED VIEW 112 913 150 153 170 120 520 174 501 300 330 320 400 943 700 600 540 310 530 ...

Page 19: ...IN M E C 3210V00043F FRAME CT 21Q41KE SFSLSB2 019A C SKD 520 6871VMMA41M PCB ASSY MAIN 019A CT 21Q41KE KMXLRA8 S 6871VMMA35G PCB ASSY MAIN 019A MOS 6871VMMA35Y PCB ASSY MAIN 019A W TXT M E C 6871VMMA41N PCB ASSY MAIN 019A W O TXT M E C 6871VMMA39H PCB ASSY MAIN 019A KIOTA KI 6871VMMA39P PCB ASSY MAIN 019A Q42KEX 6871VMMA39W PCB ASSY MAIN 019A Q41KS 6871VMMA39X PCB ASSY MAIN 019A Q41KE AV JACK 6871...

Page 20: ...NERAL SEMICON DO35 DIODE BAV21 TP GENERAL SEMICON DO35 DIODE 1N4004A T 81 TP ROHM KOREA DO4 DIODE BRIDGE D2SBA60 STK SHINDENKEN LED HTR3108BDA BK XIAMEN RED 13MCD DIODE ZENER GDZJ9 1B DIODE ZENER GDZJ5 1B DIODE ZENER GDZJ6 2B DIODE ZENER GDZJ8 2B DIODE ZENER GDZJ33B LOCA NO PART NO DESCRIPTION ZD501 ZD601 ZD901 Q102 Q103 Q301 Q402 Q442 Q551 Q552 Q553 Q554 Q555 Q571 Q621 Q651 Q653 Q671 Q672 Q801 Q8...

Page 21: ...612 C631 C632 C633 C634 C635 C636 C637 C638 C639 C640 C641 C642 C643 C644 C645 C646 C661 C662 C663 C664 C665 C666 C667 C668 C669 C670 C671 C672 C673 C674 C675 C678 C679 C680 C681 C684 C685 C686 C687 C688 C689 C690 C801 C802 C803 C804 C806 C807 C808 C811 0CE477DH618 181 007H 181 007H 0CE107DD618 0CN1030F679 0CE106DF618 0CQ6821N509 181 007D 0CQ5621N509 0CQ5621N509 181 007D 0CQ6821N509 0CQ5621N509 0C...

Page 22: ...P07A P102 P103 P301 P601 P602 P802 P902 P903 P1201 P1203 PA1103 PP802 PP803 C258 C259 C546 FR441 FR442 FR443 FR802 FR901 J30 J33 J39 J67 J81 J149 J154 L10 L251 L252 R01 R03 R04 R05 0LA0101K119 0LA0681K119 0LA0681K119 0LA0681K119 6174V 6006E 6170VC0003A 6170VMCB01K 366 921B 366 921B 366 921D 366 921C 366 009D 366 921B 366 043K 366 921B 366 921C 366 043B 387 603E 366 009D 387 A08G 387 A05F 366 922F ...

Page 23: ...450 R451 R453 R455 R456 R501 R502 R504 R505 R506 R518 R521 R522 R523 R524 R525 R526 R537 R538 R539 R540 R542 R544 R551 R552 R553 R554 R555 R556 R557 R558 R559 R572 R573 R601 R602 R604 R606 R608 R609 R610 R611 R631 0RD1002F609 0RD1501H609 0RS2702K607 0RD5100H609 0RD0392H609 0RD1001F609 0RD2401F609 0RD4701H609 0RD1200H609 0RS5602H609 0RS2702K607 0RS2202H609 0RD2202F609 0RD1002F609 0RN3902F409 0RD680...

Page 24: ... 6 W 5 00 TA52 4 3K OHM 1 6 W 5 00 TA52 1 2K OHM 1 6 W 5 00 TA52 220 OHM 1 2 W 5 00 TA52 220 OHM 1 2 W 5 00 TA52 RWR 7W 1 0 OHM J PD SWITCH PUSH SDKEA3 250V 8A HORIZO SWITCH TACT 2LEAD 100G TA SWITCH TACT 2LEAD 100G TA SWITCH TACT 2LEAD 100G TA LOCA NO PART NO DESCRIPTION SW1104 SW1105 SW1106 FB801 FB802 FB803 LP802 T551 T552 T553 X01 X661 Z102 Z551 A1 A2 A2 A2 A3 JA1201 JA1202 PJ201 PA1101 P801 S...

Page 25: ...529 D4 C530 C4 C531 C4 C532 B2 C534 C4 C535 C4 C536 C4 C538 C3 C540 C4 C541 C4 C542 C4 C543 C3 C544 C3 C545 C3 C546 C3 C548 D4 C549 C4 C551 D4 C552 D4 C553 D3 C561 C4 C573 E5 C574 E5 C593 C3 C594 C4 C595 C1 C601 B3 C602 B2 C603 B2 C604 B3 C605 B2 C606 A2 C607 B3 C611 B3 C612 B3 C621 A2 C622 A3 C623 A3 C624 B2 C625 A2 C626 A2 C631 D1 C632 D2 C633 D1 C634 C1 C635 D1 C636 C1 C637 C1 C638 C1 C639 C2 C...

Page 26: ...P NO 3854VA0083A S 2001 04 20 ...

Page 27: ...SVC SHEET 3854V A0083A S SVC SHE ...

Page 28: ...Dec 2003 Printed in Korea P NO 3828VD0087P ...

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