LG MA748W 01 Service Manual

LG MA748W 01 Manual

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  • LG MA748W 01 | Service Manual - Page 1
    GoldStar Website http:llus.Igservice.com MICROWAVE OVEN SERVICE MANUAL MODEL: MA745W MA748W MA748B CAUTION BEFORE SERVICING THE UNIT, READ THE SAFETY PRECAUTIONS IN THIS MANUAL. P/NO 3828VV5S3760 May, 2004 Printed in Korea
  • LG MA748W 01 | Service Manual - Page 2
    latches, (5) evidence of dropping or abuse. G) Before turning on microv power for any-service test o, unsection within the mdmrwave generating compartments.-check the-magnetron, wave guide or transmission line, and cavityliY proper alignment, integrity, and orinection D) Any datective.or
  • LG MA748W 01 | Service Manual - Page 3
    SAFETY PRECAUTIONS SPECIFICATIONS AUT1 N INSTALLATIONS OPERATING INSTRUCTIONS URES CONTROL PANEL OPERATING SEQUENCE SCHEMATIC DIAGRAM (I) SCHEMATIC DIAGRAM POWEH OUII-1UI 5-3 DISASSEMBLY AND ADJUSTMENT 5-3 INTERLOCK CONTINUITY TEST 5 7 URE 5 8 TROUBLE SHOOTING 14.-- 5-12 EXPLODED VIEW 6-1
  • LG MA748W 01 | Service Manual - Page 4
    weight Control Complement Rating Label Location DESCRIPTION MA745W / MA748W / MA748B 120 Volts AC 60 Hz 950 Watts approx. 20% 1 (Warm) approx. 10% IM Back side Accessories Owner's manual & cooking guide Glass turntable Roller Rest This microwave oven is designed for household use only.
  • LG MA748W 01 | Service Manual - Page 5
    around the dome of the tube whenever installing the magnetron. ANTENNA Gasket FILAMENT TERMINALS --- COOLING FIN MAGNETRON CHASSIS GROUND MAGNETRON THE OVEN IS TO BE SERVICED ONLY BY PROPERLY QUALIFIED
  • LG MA748W 01 | Service Manual - Page 6
    INSTALLATIONS 1-Enfipt,i-the microwave overrand=cleaninsideltwith a soft, damp cloth. Check_for damage such_as_ misaligned door, damagaumund_the_cioor ordents inside the cavity or on the exterior 2. Put the oven nn counter, table, or shelf that is strong enough-to-hold the oven and the food and
  • LG MA748W 01 | Service Manual - Page 7
    OPERATING INSTRUCTIONS FEATURES Oven Front Plate Window Door Screen Door Seal Display Window Control Panel Safety Door Lock System Turntable Roller rest CONTROL PANEL MA745W MA74BW MA748B
  • LG MA748W 01 | Service Manual - Page 8
    The following is a description of componeuLiumlious du.iny oven operation. 1. SETTING THE CLOCK STOP/CLEAR CLOCK - 110' NUMBER -0- CLOCK ex.) To cat 1.30,touch number key+14,[3 atit14-0-]. NOTE: 1) Thic a 12-hetir-siock. 2) operate as long as power is applied to the oven. 2. CANCEL FUNCTION
  • LG MA748W 01 | Service Manual - Page 9
    im9-!-Ic!r'v•ium;1,11'! 1 CI• !! mrsi7-77lir-m:7217•7!!.71r-1! • ••• • a IIMM liNftlI•AR=M • Idel,11:iel:• • • MIZZITi z amr• ial:A=IIM li 7,7nW7Z0 •' tt5MSSW • EVIF7L IN r4 I INN67 I ET117=IMII!EMmMm- imm:=:=mEN I MEM aZ11;41 Z,\W . iffEZIO • E I .T1• • WM! I lMitgE ll-11II=I
  • LG MA748W 01 | Service Manual - Page 10
    SCHEMATIC DIAGRAM (II) *Check the Rating Model No. (ADD Noise filter) NOTE. 1. DOOR IS OPEN. 2. RS: SENSING ELEMENT RC: COMPENSATING ELEMENT 3. WIRE COLOR. SYMBOL COLOR WH WHITE BK BLACK BL BLUE YL YELLOW PK PINK RD RED GN GREEN BN BROWN WH MGT/OVEN THERMOSTAT ON WH AC 12O V/6OHZ SINGLE PHASE
  • LG MA748W 01 | Service Manual - Page 11
    GENERAL DETAILS • The low voltage transtormer supplies the necessary - valtage-to-the-micorn-carrtraller- when-riower- card-is plugged in. -•-When-the-door-is-closed-the-primany-switch-is-ON-the secondary switch is ON, and the monitor switch opens contact COW and NO). WHEN SELECTING COOKING
  • LG MA748W 01 | Service Manual - Page 12
    of any certified oven unit found to have a microwave repair any mit found to have excessive emission levels of the excessive ea cage The service personne should instruct the owner not to use tle unit unti t oven has been brought into compliance. • If the oven operates with the door open, the
  • LG MA748W 01 | Service Manual - Page 13
    the measured values for future reference. Also enter the information on the service invoice. • The microwave energy leakage should not be more than condition, functioning properly and genuine replacement parts which are listed in this manual have been used. • At least once a year, have the
  • LG MA748W 01 | Service Manual - Page 14
    . 5) Disconnect the leadwire from connector(CN1) of the PCB SUB ASS'Y. Lift up and pull out control panel CAUTION: DISCHARGE THE HIGH VOLTAGE CAPACITOR BEFORE SERVICING (refer to page 2-1) 5-3
  • LG MA748W 01 | Service Manual - Page 15
    1) Discharge the high voltage capacitor. 2) Disconnect the leadwire from fan motor, and high voltage capacitor. 3) Remove the two screws holding the the suction guide ASS'Y to the oven cavity and remove the high voltage diode earth screw. 4) Remove the two screws holding the fan motor ASS'Y to the
  • LG MA748W 01 | Service Manual - Page 16
    H. AIR DUCT ASSEMBLY REMOVAL 1) Disconnect the leadwire from lamp. 2) Remove the mounting screw to Latch Board. MAGNETRON REMOVAL 1) Disconnect the leadwire from the high voltage transformer. 2) Carefully remove the mounting screws holding the magnetron to the waveguide. 3) Remove the magnetron ASS
  • LG MA748W 01 | Service Manual - Page 17
    K. PCB ASSEMBLY REMOVAL 1) Remove-the-control panel assemblTtmrttiecavity. (flefertcrcontrol panel assembly removal on previeus-page7) 2) Remove screws which hold the PCB SUB ASS'Y to the control panel. 3) Disconnect the flat cable from the PCB SUB A-STY-and take o Control Panel PCB Sub As L.
  • LG MA748W 01 | Service Manual - Page 18
    0 CO GI= MISILVk • I. •7\ =MMIZI= ?2,22Ed-..W IEMPM Illllllllll.r •1010101E0 110I1[•' sou 4 -1 -• • .MI111$.7= '11•111== MODKRIR L•1011111A10EeiIMR= ■ • • ■• ■ I e107.1010 MI•0101401VI IMAM rlaYm rin -Y -Aa • == lo F F . I I I. MI14.-.F M. -7111 F I \ MLA 'I' Virg= 14I4]
  • LG MA748W 01 | Service Manual - Page 19
    8-9 •• evutlui :IOUJJON WL40 I. uap.sse E111.! VJElL:d1.21...J • Usual•d:r:r:i-Am •• • ~nnr.T.v.W!N.Y.MIi7.1r.rii•1•-\'kIIral- s!ssuip_pi. lueuseu (000I.XEI :8 aw-wt40) •eoueraiseketweinseen *e E.u!uuJai lua)e113 • V :eteos as •1 EqS!S 6 of 6u!pu!M Tueweit o.16 0l ougou!m Aiewp reaTiab
  • LG MA748W 01 | Service Manual - Page 20
    COMPONENTS HIGH VOLTAGE CAPACITOR TEST PROCEDURE Antenna ,, Gasket 0 Chassis o - Filament RESULTS NOTE: When testing the magnetron, be sure to install the magnetron gasket in the correct position and be sure that the gasket is in good condition. Measure the resistance. (Ohm-meter scale:
  • LG MA748W 01 | Service Manual - Page 21
    x 1000) Normal: Approx. 100 - 150 ohm Abnormal. Infinitu or several ohm. NOTE . • A MICROWAVE LEAKAGE TEST MUST ALWAYS BE PERFORMED WHEN THE UNIT IS SERVICED FOR ANY REASON - MAKF SURF THF WIRF LFADS ARF IN THF CORRFCT POSITION • WHEN HbMOVING I HE WIHE LEADS I-HOM I HE PAHI S, lit SUHE I O GHASI
  • LG MA748W 01 | Service Manual - Page 22
    UMS APPLY, PLEASE INSTRUCTT MICROW UNNECESSARY SERVICE CALL. CAUTIONS 1. Check grounding-before-checking for trouble. 2. Be careful of the gh circuit use metallic foi- king except where-noted- In the cooking guide Do not use any type of cookware with metallic bumming. se piasuc wrap or ii
  • LG MA748W 01 | Service Manual - Page 23
    Cur drnurlY. Poo i ui y. Defective PCB 1110- assembly. Loos connec run. Everything works as specified. Dcfcctivc kcy membrane assembly. Still have trouble --D. Defective PCB asembly 4. Random programming when touching r-- other pads. 5. Display is fixed at some figure and can not accept any
  • LG MA748W 01 | Service Manual - Page 24
    and no input is accepted. CONDITION use blows. CHECK heck conthul of monitor Switch (WI door qed Replace fu RESULT ontinuity. No continuity Check continuit Ff=primucry -switch4with dooroaened Continuity. No continuity. Disconnect one -Ro• side of the wire lead connec -from transformer to the
  • LG MA748W 01 | Service Manual - Page 25
    • program times are set and START pad is touched. CONDITION S41ting time _does not count down when touching START pad. CHECK RESULT CAUSE er rontinint--v, -p.. No continuity. secondary switch (with door closed). Continuity. -a.- secondary -witch REMEDY ndary -wit -- AI- Check the con -1
  • LG MA748W 01 | Service Manual - Page 26
    oscillati (Display-operates-propW) CONDITION o microwave oscillation. CHECK DiSCv wire I relay P and heck continuity of relay2. perate the RESULT v L.vnunuuy. Continuity Checkh h vol normal 9 ge capacitor. Check high voltage diode. norma normal Abnormal CAUSE ethos REMEDY ep ace elective
  • LG MA748W 01 | Service Manual - Page 27
    INTRODUCTION EXPLODED VIEW 0 e 42. 0 OVEN CAVITY PARTS INTERIOR PARTS DOOR PARTS BASE PLATE PARTS LATCH BOARD PARTS CONTROL PANEL PARTS 6-1
  • LG MA748W 01 | Service Manual - Page 28
    hEVh DOOR PARTS 0 .54 1355* 13536 0- 21* 13720 13352 14026 (497o►4
  • LG MA748W 01 | Service Manual - Page 29
  • LG MA748W 01 | Service Manual - Page 30
    OVEN CAVITY PARTS 33112U WSZ185 33052A 36549S fi D013 33390G 35889A For model MA745W p_ .TT01 .MA748W I CI T02 For model ! MA748B 6-4
  • LG MA748W 01 | Service Manual - Page 31
    LATCH BOARD PARTS (694 ea a, ef, 55262 . m .O° I OD ®' kl 43500 C) o 466001 i3 466003 0 rilg- CIVSZO4 6-5
  • LG MA748W 01 | Service Manual - Page 32
    #EV# INTERIOR PARTS (I) Model: MA745W MA748W MA748B * Check the Rating Model No. 568771 Check the rating label of Model and order SVC parts according to the Model No. ki* * Check the
  • LG MA748W 01 | Service Manual - Page 33
    #EV# INTERIOR PARTS (II) Model: MA748W 101 MA748B 101 * Check the Rating Model No. 568771 56930 Check the rating label of Model and order SVC parts according to the Model No. *
  • LG MA748W 01 | Service Manual - Page 34
    hEVh BASE PLATE PARTS 63302 56170D fl 1frflIffrfl 1 fl 2S. _aeeaaa aa aaaaa aa 4B• e°0 ,a43 a a eaa a a4433ee. a as S. fl A TTOD1 el -€(4 ,I I --(>
  • LG MA748W 01 | Service Manual - Page 35
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GoldStar
Website
http:llus.Igservice.com
MICROWAVE
OVEN
SERVICE
MANUAL
MODEL:
MA745W
MA748W
MA748B
CAUTION
BEFORE
SERVICING
THE
UNIT,
READ
THE
SAFETY
PRECAUTIONS
IN
THIS
MANUAL.
P/NO
3828
VV5S3760
May,
2004
Printed
in
Korea