Midea EG8525X-Y User manual

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MODEL: EG8525X-Y
~~~~V

VE
POSS
I~. ~~ 0 ~ol attempt.tooperatethisovenwith C.Donotoperatetheovenifitisdamaged.
l t~e dqpr or;'en.c$inceopen-doorope~ation It is panicularlyimportan~thattheoven door
:i,..I "anresuft Inharmfujexposllretomicrowave closeproperlyandthatthereisnodamageto
!jte~ergy.It..isi~portant~oltodeieator the(1} Door(bent),(2)hingesandlatches
tamper\vlththesafetyInterlocks. (brokenorloosened),(3)doorsealsand
'8'0 I . b saaling surfaces~~. 9 notp ace any object etween .
; [~venfrontfac? andthedoororallow D.Theovenshouldnotbeadjustedorrepaired
,; cf~oiJ'!Jrcteac~erresiduetoaccumulateon byanyoneexceptproperlyqualifiedservice
1 ;saaftngsunaces. personnel.
SAVE-'-HESEINSTRUCTIONS
-- 0- - 0- . Lccc-
.
MPQ)RTA~T c .
NSTRUCTIONS
servicefacilityforexamination,repairorreplacement
Do not attempttoserviceOTrepairthisappliance.
,O. Do notcoverorblockanyopeningsonthe
appliance.Do not store items ontopofmicrowave
oven if there are louverson topofoven.
1'. Do not store thisappiianceoutdoors.Do not
use this productnearwater forexample.near
a kitchen sink,ina wetbasement,ornear a.
swimming pool,andthe like.
i 2. Do no[ immersecordor pluginwater.
i3. Keepcordawayfromheatedsurfaces.-
14. Do not let cordhangover edgeortableor counter.
15.When cleailino surfacesof doorandoven ths.t
cometogetherondosingthedoor, useonlymiid,
nonabrasive soapsor detergentsappliedwith a
sponge or softcloth.
16.Toreducetheriskoffireintheovencs.Vity:
a. Do not overcookiood. esp~ia1lysta~'y
items suchaspotatoesandfattyitemssuch
as bacon. Carefullyattendappfianceif paper,
plastic. orothercombustiblematerialsare
.placedinsidetheoventofacilitat.ecooking.
b. Removewiretwist-tiesfrompaperor plastic
-. . .
bagberoreplac,lngbagInoven.
c. Ifmaterialsinsidetheovenshouldignite,keep
ovendoorclosed,turnovenoft,anddisconnect
thepowercord,orshutoffpoweratthefuseor
circuitbreakerpanel.
d. Donotusethecavityforstoragepurposes.
DonQtleavepaperproducts;cookingulensils,
orfoodinthecavitywhennolinuse.
e. Donolputmetalinsidetheoven,exceptas
speciiicallydescnbedInIhemanualor
cookbookifsupplied\vilhthisoven.
SAFETY
- -- -
r
When\.1singelectric:!appliances.basicsafe~
pre?~utionsshouldbefollov/ed.includingthefollowing:
Vy~.RN1NG~!oreduceIheriskofbums,electrical.
Si1oc~.. firs, Injury to persons or exposure to excessive
mit:-6~v2veene~y:
i.tR~.OALL.TH=INSTRUCT1ONS SEFOREUSING
,-.,-ApoUANC'-
. IMc.. c:.
2.;RJad:and follow the sDe!:iiic -?rer...autions ~oavoid
, .
:pos~ibleexposuretoexcessive mic..owave energy-
, . .
;.ounoaoove.
;
3.:T~is appliancemustbegroundedandproperiy
. P9,ca~z.e?Conneotonlyto~properly.groundedand
po'~fe-:1olitIeLS:e -GrounotngInstrudons-onpage3.
4.lnst~lIor locaiethisappiianceonlyinac:ordance
'vlitl1theinstallationinstructionsdescribedinthis
:.manual.
: r"
5.iSomeproducts suchasY/holeeggsandsealed
ii::ohtainers.suchasclosedglassjars,mayexplode
.;ankishouidnotbe heatedinthisoven.
I
6.; Vfie t~is 2.~piianceonlyforits intendeduse.as
de$cnoed In the manual.00 not usecorrosIVe
'!cn~ry1.1calsor vapqrs inthis appliance.Thistypeof
,ovenls specifically designedto heat.cook,dry,or
:o~irost food. It is noLdesionedforindustrial.
'!a~br~tory. orcommerdal-use. Iti~intendedfo~
!"hdi}1euseonly. 09 notusefordryingdothes. linens,
n~wspaper, or similar non-loodtypeitems.
7.j Make~:sure-that all personsusingthisappliance. .
~speciajly chlidren, areclosalysupervisedand
propsriyinstructed onhowto usathisappliance.
I 8. D~:n6toperatethj~appliancei.iith2Sadamaged
rC~d prplug. ii i: isnOI workingproperly,orif it has
j.b~~n oamaocd ororopped.
f\.tf,H~s.~ppiiariceShouldbe servicedonl}'byqu~l!fied
i 5e~lc~ personnel. Contacttheneares:authonzed

TABLE OF CONTENTS
cl!use contents paae
00 IntroductionandSafety precautions
1
2
3
4
5
1
2
3
4
5
Introduction
SafetyPrecautions
ExplodedViews
SchematicDiagrams
Parts List
Heating Principle of Microwave 6
Trou bleshootingProcedures 7
Common breakdown and means of repairing 12
Critical PartsServicing 13
important thingsto do prior to critical parts servicing
interlock assemblyreplacementandadjustment
door andhingereplacementandadjustment
magnetronreplacement
13
13
13
13
2
3
4
Safetychecksandtests after servicing 14
1
2
3
14
14
15
constructional checks
insulation resistance test
microwave leakage test

IN,TRO~UCTION
~is Microwave OvenServiceManualisprinted in alooseleaf fonnat. Eachpart is
qivided into sectionsrelatingto ageneralgroupof componentsandeachsectionis
s\ibdividedinto variouspartsdescn"bingaparticularcomponentor serviceprocedure,
Thesubdividingof thesubjectmatterplusthelooseleaf form Will facilitate theupdating
of themanualasnewor revisedcomponentsandserviceproceduresareintroduced.
Eachpageof this servicemanualwill beidentified in thelower right handcomer8ndas
dewor revisedpagesarepublishedit will beeasyto keepthemanualupto dateby
following thefiling instruc~ionsonthecoverletter.
ThisServiceManualis avaluableservicetool and.careshouldbetakento keepit upto
dateby promptandproperfilling of subsequentpagesastheyareissued.

SAFETY PRECAUTIONS
T~IS ~A~UAL, ASWELLAS THE INFORMATIONCONTAINEDIN IT,ISTO BE USEDONLYBY
AN AUTHOR'iZEDSERVICETECHNICIAN FAMILIARWITH AND KNOWLEDGEABLEOF
P~O~RSAFETY AND SERVICINGPROCEDURESAND POSSESSINGHIGH QUALITY TEST
E~U1PMENTASSOCIATEDWITH MICROWAVEAND ELECTRICALAPPLIANCE REPAIR.
ALL INDIVIDUALS WHO ATTEMPT REPAIRS BY IMPROPER MEANS OR ADJUSTMENT,
S~BJECT THEMSELVES AND OTHERS TO THE RISK OF SERIOUS OR FATAL INJURY.

THE HEATING PRINCIPLE OF MICROWAVE
Microwave Is one kind or radio wave wll()Sewayelenctll is yery soort, rrequency is yery high. Therefore, it is called uitrahi~h
frequency electromagnetic wave. Microwave can hcat f()()(1mainly result in the mutual affect or the food in the microwave field
and the Dlicrowavc field ilsclf.
tinder the affect of microwave field, the II\Crmal efr«1 olcchanism prcxJuccdfrom tile mutual .rrea of the microwave and Ihe
fncMiIncludes two aspects~One is Dlelcctrlc I~s of pIlar molecule, the oll~r is CIJRducti.eIUS5of ion.
Usually, focxlis cvl1stitulc of nrganisnl( plant and animal). Tile org:.nism i~ fornlcd by all kinds of (KJlar-:waterIIwlecule. polar
protein molecule, and all sorts "f salt ion. Tile center uf ~ra"ity or the positive and negatiYccharge in the moleculeIs not coin-
cide. In normal condition, tile mulcculc Is in irrCI'llar Ilrder due tl) its thernlal acliun, thlls the food do not appear (KJlarily.
(FIG.. - la). Under Illc actiOlI or uuter electric fieill. lIte pclSitiye end of the IJ('lar molecule trend to the negative electric
rield. tbe negative end or I1Olarmoleculc trend to the positive electric field. and sonlcwhat arrange In order thruugJIthe direc-
tion of the electric ficld( Fl<i.1 - Ic). Tltis pltenolnel14lnusually becalled MTORQUEPOLARITY". WIlenthc outerelectric
ricld apply for the up~itc IJ('larily, the (XIlar DIOlcculcllacn arrange an ol'(XIsite directloo order accordingJY(FIG. I -Ib). If
tile direction or tlte outer clcctric neld changed repeatcilly. the (XIlar molecule WIMlldrepeatedly sway accordingly. During the
swayi"l. it is understalKlllIg that the polar molecule Wllliitl produce heal duc to sclmewhal sllnilar friction anlOl1&them. When
(b)
FiJ:J-
, the electric neld is applicd for ultrahigh rrequenl lulcruwave neld from the outside. its direction would change tens billion
times per second. sodo the mulccule" This kind or nlfllccutc ~wa)'ing prooucing Ninlilar frictiuo.l heat frlllll the interference
and block of the action strength anions tile mt)lecule. and,chanKed to mocr()ScopicmlcnJwave hcating. Micr(lwave heating mlt
only concernedthc nature or the nlatter itself. but Dls" cklSCdlyconnectedwith thc electric field strength and rrequency. When
the frequency Is Inw, thc molecule swaying:rate and the ncute degreeof the mutual friction amo~ the nlOlcculeIs low, and
would producemuch heat. When the frequency is too Iligh. a~the swinJ or the polar molecule is witll nltating inertia. it made
the swlnl do not in line with the changin~ rhythm of the electric field becauseof the frlctiur. drag. thus. actually lowed tile po-
lar molecule swaying speed. l"he friction draglng degree is concerning about the magnelcctric wave frequency. polar moJeculc
~"ape, and the matter's sticky degree. To difrcrentJllattcr' s nloleculc. IIlCre arc different -'lJecial rrcquency lone. Thoseaho
absorb nticrowave energy rmm fhe.~ezonc are nlost call1lhie to turn nlicrUWHVCener~y to lleat energy.
Apart from the above said action. there Is another acticln which Is clectric ion under tIle action or micn~wavefield. act nercely
accompanied with the acceleration or clcctric field. Tllc J1OSitlve1011transfcr to thc negative Plliarlt, or the field while the 11eg-
atiye Ion do opposite. Accompaning with the ch8"lin~ elcclric field. the elcctric Ion chancing acccwdingly. During the trans-
fcrinl, heat !'n,)ducedwi'th the crash anHJngIhe ion. This kind or 8cti(NI take the nlain erfect tu those Inlcrowaye hulinl or
.llllh salt molecule.
No m.Uer It Is the polar molecule swayin. M the ion transrerinl. they both are turniRi the n11crnwaveencrJY which the heat.
ins lD8Uer lOt from Ihe Rllerow"ye field to heat enerJY. I'rool the analasis or IIlcory, we c.n draw luch . cuncl1l8ioDthat the
power which. unit or volume Dlatler ab8O1"bedfrom tile Inlcrnwaye field 8-' the foUowinl ronlula:
P.- KE lEct~o
PaStandi for the lXJWerthe heatedmatterabsorbedff'N" tileloicfowavefield.
K ~t.nd$ for a canstanl
E Standf,. nai~rowavefield strength
r Standsfor themicrowavefrequency.
to:" ~bnd. 'tV' lna. .".1- , ..1 .h. k__'..A -.'..r~

TROUBLESHOOTING PROCEDURES
1~W8 ~~ullq a mkI'owayc oyca. 7OU.houid Juctp the '"-kdown and the cauae ~cctl,. tIleD JOUcan repair It with
~~ ..'1. The oycrhaula,. DlU8t be pcoceed la order. an, ba8t, conclU81on II DoC r~_~ble. OCbcrwl8e OY1~~IWOUId be dWIC when rcpalr. The aalcrowa.e 0." ala' ~ cor.1pow1d brcakdowa due 80 aU kJadI 01 dlrrercnt
\rJ.-;:~tbul. wbea oycrbaui. &bey all lbould be t8kc Into coD8k1cratlon. :5peclalaUentioa mult be Ii..n 80 the microw..e
IJkap !alMitheelectricbIIulaUoowheDU8mlDebeeau.ethe7maydoharar.fulto thercpalrlnl Ita".
II" I lME:A:NSOP THE BREAKDOWN EXAMINING.
I .
~.ou.m1ne a alluowa.eDYeD.Ith breakdown?A bettcrmana whichdcmOllltratedInpracticaloperat ~
Insp.c:tlna.nd II.tcnlna. Oathebull orlarle amount.or pereeptU81knowledle.JOUcanJudp and8.17111tbebreak.
I '
doWnquicklyandcorrectl.
I. las~lol1.
t~pect whctber the ovenshapeIs disorderedand wher~ is the disordered position. Ifany. lC is IQ'mal If the cabinet
d'liordued a little. but abn«malll the oyel1.the doordisordered. the dcxwhookbroken, the dOOI'crooked. w thereare
t~ lauch looscnas betweenChedoor and the ovenafter the door Is closed.
,
2. UtteRIng.
~Cenlnl to the yoiceor the oyenoperatingand Chenoise01CheIan aftu ICconducted. Minor "weo wen" ~e. crcU",
Mbla" noiseand "shishl" noiseshould beconsidcras normal. But it is abnormal II the followlnl noiseoccured:
I
, (.1) SOund"wen wen" nolle.
(~) Lana tunc "shishl- noise.
, (13)StrIke yoice like "plpa llipa-.
.,
! I SPOTEXAMININGSTEPSOf THE MICROWAVEOVEN.
a. ExaminethemlcrowayeInsulatlnl resistance.
MeasuretheInsutatlnl rCiiscancewithaaYOIlieterora melaohmnlelerrIlevalueahouldnotleis tban2 mepohm. Oth-
""e. partumlnatloo shouldbetakenat once.Suchaschecklnawhetherthemotor, thethermalcutout, thetrans-
fonDeror thecapacllwareelectricItylaklnl.
I2. £Uml~tlon or the resistancevalue 01the mlcrowayeoycn.
CtoIe tbe door, aetthe time,(the oyenIs at opcratlnl condition but the powerplul havn' t baD pluged In). .easurc
, thetwolect(L- N) 01thepowerplugwllh Rx I Ifadeof a ayomeCer.therealatanceyaJueshouldbeabCMIC~.5 ohm.
U OIleRcircuit occurcd. Chenyou must check whelbu the SA fuse II broken. Cheprimary wlndlna of the Cransformer Is
~ circuli. Chethermal cutout is opencircuit or not, 1011must check whether the Interlockdeylce II put Chroup or
:
~Uthe plull are connectedwell. If sllOftcIrcuit occuredor lhe r~lst&nce lesl Cban1.5 obm. 1OU.bould cbeckwbeCher
tbcprimary wladlna 01tile powertransformer is short- clrculled or part Ihort - circuited.
3. Sumlnatlon of mlcrowa.e leaPle.
Mulure the mlcrowa.e leakale wllh a mlcrowayeleakale measure. Placea Ifaduate of 275ml water aCthe middle of
the alUI tra1 01the o.en (fiG. 5- 1). Closethe door, powerlel bllh, time seCCo3 minutes, preu tbe scartln. button
t~~ate the oven. Aftu recitlned Ihe microwave leakale measure. measurearound tbe door crack, thoseholepoll.
~Icxaof the window and the air yent at fwr sidesof the oyenwith lhe probeof the measure. Wilen measure. chemoylna
~Peedof tbe probeshwld not exceed15mm per second.and ChemersurlnBdirection should beChesamewllh the outlnl
dlrmioa ortbemicrowaveleakale(FIG. 5-2) .
.. c
~a1 measuriBI. the ultimate valueof microwaveleakageor all the measuredposition should not exceedI mllllwa«'
_a. or .bould beconsldued as abnormal.
4. ~mlne when the ovenat operatlnc. but the food 'can't beheated.
(1) Examinewhen the lam&)is on. t~ Ila.s tra1 is c1cllns. the fan operating In normal:
,
Take off the cabinet. sl8rtlnl the o.en, measuretbe pluSof the transformer wllh a ayometu to seewhetherIt II e.
DOUIbto 110v. Ir It is enoulh to 110Y. then the secondaryblBh voltaic of the transformer lhould beexaminedas
FIG.S- 3.

MeasureIt with the2S00Valt~rnatlnsr.radeof model500avometer.Oner~ of theavometerconnectthe Iroocore
of the transformer. the other t~ coonectthe secondaryhigh voltageplug (FIG. S- 4). The avometC1'reading
shouldbeabout2100V(whenmeasure.becarefulwith thehip voltage). If novoltageat all. it Indicatesthat the
trapsformerhasbroken.andshouldbereplacedby a newone. If It I, enoughto 2100V. then eheckthe filament
voltageof the transrorll1erwith alternatingIOVgradeof a avometer.the valueshouldbeabout3.4V (FIG. S- S).
~
.~ s.c.-d8ry .W'"
Tranl[- y,or..
",JJ-r
l~
., ..~ \r
--
Pri-rJ wl8618. Fia.5- 4
PII.5- 3
FIs.5- 7
Fil' 5- 5 FiB.5- 6
If thereis novoltageat all, it indicatesthetransformerhasbroken, andshouldbereplacedbya newone. If it is
enoughto 3.4V, checkthe filament resistanceof the magnetron,measurethe filament plug with the R x 1 Irade
of a avometer(FIG. S- 6). If It is open- circ~ited, it indicatesthe magnetronhasbroken,andshouldbereplaced
bya newone. It is normal if the resistancevalue is very small. Then checkwhetherthe magnetron.teel has
brocken,If broken, replacewith a newmagnetron.
U thereis noproblemwith the magnetron,checkthe high voltagediodethen. Measurethe diodewith Rx 10K
sradeof a avometer.the" +" rodendor theavometerconnectthe cathodeof thediode, the" - " rodendof the
avometerconnecttheanodeof thediode(FIG. S- 7). The avometerreadingsbooldbeabout150thousandohm.
Thenchangethe rod to different electrode,the readingshouldbe..~". If the readingis very small, andnearto
shortcircuit. it indicatestile high voltagediodehasbeenpunctured,andshouldbereplacedbya newone.
FII-5- 9
FiB.5- 8

If the high vmlaBe dlcMJeIs OK. -then check the forwardjna plua of the tranlformer to lee whether It il enCMIpto
120v, If It I. not enclClgh.check'the micro- switch of the time and (XJwerdistrIbuter. Connect the two rOOof the
avC)lneterto the 1.1 place of thc timer with RX IK grade. It is norm. I If the rcadlqll wOwwhcnIt tu& offtondl.
tlCMI,'If the readiq iJ W~", It Indicatesthe microswitch has broken. and the timer lhould bereplacedby a new
c)ne.If all the aoove.examination shows normal. then check whether tllc terminal pluS of the magnetron .nd the ca-
pacitor have «x)5ed.If It I. l(M)Sed.pinch II IIShlly with a pliers.
S. ~mloe the startloB and the
i Pull out the ~wer plUI. take off the cabinet, dlscharae the <:8P8cltor. measure the rcsllta~e .lluc or the primary
wlndina .nd the lecondary wlndlns of the tranlformer wIth a avometer (FIG. 5 - 10 and FIG. 5 - 9). The reslltance
.alue of the prImary wlndinB should beabout 2.2 ohm. Ihe secondary windlns shwld be alMJul130 ohm. oCherwlse, il
Indicatcs the transformer has brokcn. and should be replaced by a new one. -
.-:»;
.~/
Prl_, wtadl.
FI..S- 12 Fia.5- 10
Fla. 5 -I
If the transformer is nOl'mal, then the hAShvoltage ~pacitor should bechecked. Pull wt the connectI111pluS of the ~-
pacitor, and mealure It with R x I grade of a avometer, the two rod of the avCHnetercooocct the two polarity or the~-
pacltor. When they jUit connected, the readlnl of the avCHneterIhwld be zero, then enlarle to nine mepohm Ilowly.
Chanse the roo to different polarity. the readinl repeat from zero to nine mepohm (FIG. S- 11), it meaM the ~pacl.
tor Is normal. If the indi~tor of the avometer ~n't.point out from zero to nine mepohm, It Indiatea the hiah YOltale
~pacitor bal broken, and lhould be replaced by a new one.
U It il normal between the two pole of the capacitor, then the IMulatioo between the ~p8citOl' pole and the ~blnet
lhould be measured with R x IOK grade of a avometer. The reilitance value IbouJd be M -" (FIG. S- 12). Ir It Is
short circuited or have a number readinl, It indl~tel that the capacitor has beenpunctured or electricity lceked, and
Ihwld be replaced by a lame mooel, same capacity one.
If the reliltance value of the capacitor' I two pole are" -", the capacitor II norn,al. Then check the earth or the mal-
netroo'l two filament to sce whether they are short -circuited(FIG.S- 13). If theyareshort- circuitedandthefila.
meat strikes the Ihell or the magnetron, It Indl~tes the magnetron hal broken, and should be replaced by a new, lame
model ooe.
If the magnetroo Is allo normal, then test the pilot switch. Pull out the two plup or the switch. Masure It with the R
x 1 grade or a avometer, the two roo cooocct the plug or the switch, the reslltance value should be ..m" ( FIG. S- 8) .
Thenpre.sdownthepilot switch with a screwdriver,If the radlnB of theavometerpointedto zero, It Indicatesthepi-
lot switchhasbroken,andshouldreplaceIt with a new, saInemodelooe.
I. REPAiRING METHODOF SEVERALBREAKDOWN
... Repair whenthere~~URd lafle amountsmicrowaveleakage.Thereare many facton which may causemicrowave
leeklng. Followlq mentionedmaybethe maincauseof ml~rowaYeleakale:
(1) Thedoordeformed.the hlnaelooscdor damagedthat causedthedoorQn not~I~ tilfltly.
(2) Thed~ pmslDBcoveror tbeembedpiecedamaBedor comeoff.
(3) ObylCMIIdam-Ie or unevenof Iheoven.
I
(4) There are filth belween the dCXJrand the oven.
C5)Thedoorandtheovenareseriousloosedafter thedoorclosed.