7067664 Nguyen Li Cau Tao Va Hoat Dong Cua Radio
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Transcript of 7067664 Nguyen Li Cau Tao Va Hoat Dong Cua Radio
RADIO_CASSETTES khi Radio Cassette Ni dung : Phn tch s khi ca Radio - Cassette, cc biu hin khi h hng cc khi chc nng 1. S khi ca Radio - Cassette .
S khi ca Radio - Cassette Phn tch s khi ca Radio - Cassette 1. Khi ngun ( Power) : Khi ngun c nhim v cung cp ngun mt chiu t 9 n 12V cho tng cng xut Audio v p DC6V cho cc tng Graphic Equalizer, Radio v tng khuych i u t (Head amply ) , mch Regu l mch n p c nh, to in p 6V 2. Tng khuch i cng xut m tn ( Audio Amply ) : Khuch i tn hiu m tn t khi Equalizer a sang cho mnh ri a ra loa pht ra m thanh, khi ny s dng ngun DC t 9 n 12V 3. Tng Graphic Equalizer ( chnh m sc ) : Tng ny gip ngi s dng iu chnh sc thi m thanh nh iu chnh tn s, iu chnh Bass -Treec, iu chnh m lng . 4. Tng khuch i u t ( Head Amply) : Tn hiu m tn thu c t u t rt yu c tng ny khuch i ln bin ln trc khi a sang tng Equalizer . 5. Tng Radio : Tng Radio thu sng t cc i pht sau tch sng ly ra tn hiu m tn cung cp cho tng Equa lizer. 6. Chuyn mch Function : L chuyn mch la chn Radio hay Cassette, chuyn mch bao gm chuyn mch tn hiu v chuyn mch ng cp ngun cho cc tng Radio v Khuych i u t.
Radio - Cassette SONY Cc biu hin ( bnh c trng ) khi hng cc tng ca my. Hng khi ngun : My khng c n bo, khng vo in, bng khng quay. Hng loa : Mt m thanh hoc m thanh b d. Hng tng cng sut ( Audio amply ) : Khng c m thanh hoc m thanh ni nh v nght mi. Hng Equalizer : Khng c m thanh hoc m thanh ni nh Hng mch n p (Regu) : C n bo ngun, bng c quay nhng khng c m thanh , c Radio v Cassette u mt. Hng u t : Radio ni bnh thng , cassette ni nh v ch cn ting trm , mt ting thanh. Hng tng khuch i u t (Head amply ) : Radio ni bnh thng nhng khng c m thanh Cassette. Hng tng Radio : Cassette ni bnh thng, nhng Radio khng c m thanh.
c th sa c cc bnh trn, cc bi sau chng ti s gip bn tm hiu nguyn l hot ng chi tit ca mi khi , v phng php kim tra sa cha ca tng bnh c th.Khi cp ngun Radio Cassette Ni dung : Phn tch nguyn l hot ng ca khi cp ngun, Phng php kim tra s cha khi cp ngun. 1. Khi cp ngun ca Radio - Cassette. a) Chc nng cc linh kin trong mch cp ngun v cc tng tiu th ngun
S mch cp ngun ca Radio - Cassette Bin p ngun : C nhim v i in p AC 220V 50Hz xung in p AC 12V. Cu Diode D1 - D4 : Chnh lu in p AC50Hz thnh in p DC , T C1 lc phng in p DC, C1 l t lc ngun chnh c gi tr khong 2200F Function : L chuyn mch chn Radio hay Cassette, khi ng sang Radio, in p t ngun cp thng vo tng cng xut, ng thi gim xung 6V thng qua mch n p sau qua chuyn mch i ti cp ngun cho mch Radio ; Khi ng sang Cassette, nu trn b c Stop th ngun dng li chuyn mch, nu bm Play trn b c, in p ngun s i qua cng tc SW trn b c vo cp in cho M t quay ng thi cp in cho tng cng xut v gim p xung 6V cung cp cho tng khuch i u t. Tng khuch i cng xut : c cp ngun trong hai trng hp - Chuyn mch Function ng sang Radio hoc bm nt Play trn b c. Mch n p : c cp ngun song song vi tng cng xut , mch n p cung cp in p 6V cho cc tng Equalizer, Radio v khuch i u t. Tng khuch i u t : c cp ngun khi chuyn mch Function ng sang Cassette v nt Play c bt. Tng Radio : c cp ngun khi chuyn mch Function ng sang Radio. M t : c cp ngun khi cc phm trn b c c nhn, khi cng tc kp SW trn b c ng li..
b) Minh ho s hot ng ca mch cp ngun trong cc trng hp : Tt my - M Radio - M Cassette .
S minh ho ng ngun Vcc cho cc tng trong ba trng hp : Tt my - M Radio - M Cassette Khi tt my : B ngun vn hot ng, in p vn tn ti trn cu Diode v t lc ngun chnh C1, v i ti ch trn chuyn mch Function v cng tc SW trn b c, lc ny chuyn mch Function ng sang Cassette. Khi m Radio : in p ngun i qua chuyn mch Function vo cp ngun cho tng cng sut ng thi gim xung 6V thng qua n n p v tip tc i qua chuyn mch vo cp ngun cho tng Radio, lc ny cng tc SW trn b c ngt , v vy M t khng quay. Khi m Cassette : in p ngun i qua cng tc kp SW trn b c, mt nhnh i vo M t, mt nhnh i xung my cp ngun cho tng cng sut, ng thi i qua n n p h xung 6V sau tip tc i qua chuyn mch vo cp ngun cho tng khuch i u t .
=> Nm vng nguyn l ca mch cp ngun trong Radio - Cassette , s gip bn tm Pan v sa cha Radio - Cassette tr ln n gin v a s h hng ca Radio - Cassette u c lin quan n mch cp ngun. => Nguyn l hot ng ca bin p ngun, mch chnh lu, mch lc, mch n p c nh chng ti gii thiu cc chng trc, hiu c phn ny , nht thit bn phi tm hiu v phn linh kin trong cc chng trn. c) Phng php kim tra sa cha khi cp ngun .
H hng khi cp ngun thng c biu hin my khng vo in, khng c n bo ngun, bng khng quay. Kim tra : ng h thang x1 , o vo hai u cun s cp bin p 220V AC, nu kim ng h ln mt cht l bin p vn bnh thng, Nu kim khng ln l t cu ch ( ngay sau lp v nha - trong bin p - trng nh con t gm ) hoc bin p b chy, trng hp chy bin p bn cn thay mt bin p khc c cng cng xut. Nu bin p tt, bn cp ngun v o in p xoay chiu ( thang AC 50V ) trn hai u dy th cp mu xanh . Chuyn sang thang o DC v o trn hai u t lc, nu in p thp hoc cha c , bn cn kim tra cu Diode, Nu c in p ra => B ngun hot ng tt.
Lu : Khi kim tra ngun bn tm thi tho rc cm in t b ngun sang my c lp b ngun. Tng K cng sut - Audio Amply Ni dung : Tng khuch i cng xut dng Transistor, Phn tch nguyn l hot ng, Tng khuch i cng xut s dng IC, c im v tr khng v in p trn cc chn IC, Phng php xc nh IC v cc chn quan trong, Phng php o kim tra loa v tng khuch i cng xut. 1. Tng khuych i cng sut dng Transistor S tng khuych i cng sut s dng Transistor Nhim v ca cc linh kin : Q3 : l Transistor tin khuch i v o pha tn hiu. Q4 : l Transistor cng sut khuch i bn chu k m Q5 : l Transistor cng sut khuch i bn chu k dng Volume : l Trit p iu chnh m lng C8 : l t ni tng cho tn hiu m tn qua, ngn p mt chiu li C9 : l t ra loa R9 v R10 l in tr nh thin cho n Q3, ng thi l mch hi tip m, hi tip tn hiu u ra tr li u vo, nhm tng cng tnh n nh cho mch cng sut R8 l in tr gnh ca n Q3 , ng thi nh thin cho n cng sut Q5
[email protected] C7 : l t lc ngun cho tng cng sut C6 : l t lc ngun cho cc tng pha sau R7 : l in tr cp ngun cho cc tng pha sau D1 v D2 c phn cc thun to ra s st p khong 1,2V phn cc cho hai n cng sut
Phn tch nguyn l hot ng ca tng cng sut Tn hiu m tn ra khi mch Equalizer c a vo u trit p Volume, tn hiu ly ra im gia trit p c bin thay i tu theo mc iu chnh ca ngi s dng => tn hiu c a qua t C8 i vo n Q3 khuch i, Q3 l n khuch i v bin in p, Q3 c nh thin sao cho UCE ca Q3 0,5Vcc ( t c gi tr ny ngi ta iu chnh R10 ) Hai n cng sut c mc y ko khuch i cho hai na chu k ca tn hiu, tn hiu vo B ra E do hai n cng sut khuch i v cng dng in Tn hiu ly ra t chn E ca hai n cng sut c cng mnh c ghp qua t C9 a ra loa Ngun nui ca mch trn c th thay i t 6V n 12V, khi thay i ngun nui ta ch vic thay i R10 thu c UCE ca hai n cng sut cn bng. Cc bn c th lp mch trn theo cc thng s ghi trong phn t lp Cassette.
2. Tng khuch i cng sut dng IC Khi nim v IC cng sut : IC l vit tt ca t Intergated Circuit ngha l mch tch hp : l mch in t gm nhiu linh kin tch hp trong mt khi duy nht thc hin mt hay nhiu chc nng , th d IC cng sut m tn th lm chc nng khuch i cng sut m tn, IC tng trong Ti vi mu c th thc hin hng chc cc chc nng khc nhau.
IC khuch i cng sut m tn trong Cassette Vi mch s dng IC khuch i cng sut ta cn nm c cc im chnh sau : Chn cp ngun Vcc cho IC Chn nhn tn hiu vo Audio in Chn a tn hiu ra loa Audio out
c im v in p v tr khng ca cc chn IC IC cng sut m tn thc cht l mt t hp Transistor c mc theo kiu trc tip, trong hai n cng sut c mc y ko v vy in p u ra loa ( Chn s 2) lun c gi tr = 1/2 Vcc Nu ta o tr khng ( bng thang x1) gia chn cp ngun vi Mass th chiu o thun ( que en vo +Vcc, que vo mass) phi c tr khng ln , khi o li => c tr khng nh. Khi cp ngun, nu dng tay cm Tvt chm vo chn Audio in phi c ting loa.
Tri vi cc c im trn l du hiu ca IC cng sut b hngPhng php x nh IC cng sut v cc chn quan trng IC cng sut l IC c to nhit . L IC c ng lin lc ra loa.
[email protected] Chn cp ngun Vcc l chn ni vi cc dng ca t lc ngun (t ho to nht khu vc cng xut ) Chn ra loa : xc nh chn ra loa, ta phi d ngc t Loa v qua t ra loa . Chn Audio in : Ta c th xc nh chn ny bng cch d t im gia ca trit p Volume qua t i vo chn Audio in ca IC
IC khuch i cng sut m tn Phng php kim tra loa v tng khuch i cng sut Hng loa : Biu hin ca hng loa l khng c ting hoc ting b d.
Kim tra : ng h thang x1 qut qut vo hai u mi hn trn loa, nu c ting st st v o thy tr khng bo t 4 - 8 l loa cn tt . Trng hp loa b d => thng do loa b chm cn, ta th bng cch n nh tay ln mng loa, nu loa b chm cn th nghe c ting st ct.. Hng IC cng xut : IC cng sut thng hng hai trng hp : Chp chn cp ngun ( c th lm hng theo b ngun ) in p chn ra loa b lch.( thng thng chn ra loa = 1/2 Vcc ) Biu hin => Mt ting ra loa hoc ting b nght mi.
Cc bc kim tra tng cng sut : Xc nh ng IC cng sut (l IC duy nht c to nhit trong my) Xc nh ng chn cp ngun Vcc cho IC cng sut ( da vo t lc to nht cnh IC cng sut, in p Vcc i qua cc dng ca t lc. ng h thang x1, o tr khng gia chn Vcc vi mass, nu c hai chiu o kim ng h ln = 0 l IC b chp. Nu chiu o thun (que en vo dng , que vo mass) kim ln mt cht, o chiu que o, kim khng ln => l IC c tr khng bnh thng. Nu IC c tr khng bnh thng th cp ngun v kim tra in p.
[email protected] o chn Vcc so vi mass phi c 9 - 12V ( bng in p quy nh ca my ), nu chn Vcc khng c in th kim tra li ngun, chuyn mch Function, cng tc SW trn b c. Nu chn Vcc c in p, ta kim tra chn ra loa ( ti IC ) phi c in p = 50% Vcc, th d Vcc = 12V th chn ra loa phi c 6V, nu in p ny lch qu 10% l hng IC.
Tt c cc in p o u bnh thng th ta tng Volume ln v dng t vt nh g vo im gia trit p Volume phi c ting ra loa => Nu khng c ting ng cng l hng ICMch chnh m sc Equalizer Ni dung : Nhim v ca mch Graphic Equalizer, Mch iu chnh Bass - Treec, Mch Equalizer 5 cn gt, Phng php kim tra sa cha tng Equalizer 1. Nhim v ca mch Graphic Equalizer Equalizer l mch iu chnh s cn bng tn hiu gia cc tn s trong gii tn m thanh, cn gi l mch iu chnh m sc, n gin nht ca mch Equalizer l mch Bass Treec vi hai nm chnh, thng thng mch Equa lizer c 5 cn gt chnh cho 5 vng tn s l 100Hz, 300Hz, 1KHz, 3KHz v 10KHz. T kin thc vt l PTTH ta bit rng, m thanh con ngi nghe c c gii tn t 20Hz n 20KHz v gi l tn hiu m tn, tn s nh hn 20Hz gi l h tn, tn s t 20KHz n 30KHz gi l sng siu m, cn tn s trn 30KHz l sng cao tn. Gii tn m thanh m con ngi c th cm nhn t 20Hz n 20 KHz nhng cc thit b m thanh thng b hn ch v mt tn s. Th d i Cassette thng ch truyn t c gii tn t 50Hz n 10 KHz, in thoi di ng ch truyn t c gii tn t 300Hz n 3KHz, cc thit b cho di tn tt l u a CD, my nghe nhc k thut s.
Di tn s m con ngi s dng trong lnh vc in t. 2. Mch iu chnh Bass - Treec
[email protected] tn s ca nm chnh Bass - Treec Gii tn m thanh con ngi nghe c l minh ho bng ng mu tm t 20Hz n 20KHz. Gii tn m thanh m Radio - Cassette c th t c minh ho bng ng mu , t khong 50Hz n khong 12KHz Nm Bass l chnh li cho vng tn s khong 100Hz., y l vng tn s ca cc m trm nh ting trng, ting m m.. Nm Treec l chnh li cho vng tn s khong 10KHz , y l vng tn s ca cc m bng nh ting xng ..
Vng tn s t 1KHz n 3KHz t thay i khi ta chnh Bass treec, y l vng tn s ca ging ht ca s, ging pht m ca con ngi.
S mch iu chnh Bass - Treec
S nguyn l ca mch iu chnh Bass - Treec Tn hiu m tn t tng Radio hoc tng Khuch i u t a sang i vo tng Equalizer theo ng Audio Input Cc tn s cao i qua t 1nF i vo trit p Treec, cc tn s thp b t cn li, nh vy tn hiu i vo trit p Treec ch c thnh phn tn s cao, T 10nF sau trit p Treec gi li tn s thp u ra khng b u tt xung mass. Mt phn tn hiu i qua R22K i vo trit p Bass, cc tn s cao thot qua t 0,1F v khng i vo trit p Bass, nh vy tn hiu i vo trit p Bass ch c thnh phn tn s thp. Tn hiu u ra ly t im gia ca hai trit p c tp trung li v a sang trit p chnh m lng Volume, sau c a sang tng cng sut khuych i .
[email protected] Bn c th t lp mch Bass - treec nh cc thng s ca s trn, Cc trit p Bass - Treec bn mua loi 100K nh hnh di
Trit p 100K dng lp mch Bass treec v trit p Volume 3. Mch Equalizer c 5 cn gt. c th iu chnh c nhiu vng tn s hn , ngi ta thng lp mch Equalizer c 5 cn gt .
Di tn iu chnh ca mch Equalizer 5 cn gt.
S mch Equalizer 5 cn gt s dng IC Bn c th thit k mch Equalizer 5 cn gt nh cc thng s ca s trn, sau bn c th s dng vo tng m hoc b kch cho loa thng.., ngun in nui Vcc cho IC l 6V DC. 4. Phng php kim tra sa cha tng Equalizer Khi hng tng Equaizer thng sinh ra cc hin tng nh . Mt m thanh ra loa trong khi bng vn quay, hoc m thanh ni nh, hoc iu chnh cc cn gt t tc dng. Kim tra : Khi kim tra Equalizer bn cn kim tra Loa v tng khuch i cng sut trc, v chc chn rng tng cng sut hot ng tt Dng xng hoc l RP7 st vo cc trit p Bass -Treec hoc cc cn gt, loi tr bnh khng tip xc. o kim tra Vcc cho IC mch Equalizer, thng thng IC ny nm ngay cnh cc cn gt iu chnh tn s, chn Vcc l chn c t ho 47F hoc t 100F lc ngun, in p ny phi c 6V DC Nu mt Vcc cho IC Equalizer bn cn d ngc li theo ng in p ny v pha IC cng sut tm ra mch n p gm 1 n v 1 diode zenner, bn hy kim tra n v Diode zener ny .
Cui cng nu in p c th bn hy u tt t u tn hiu vo Audio in n u ra Audio out ca mch Equalizer, nu c m thanh th l do hng IC Equalizer.
Nguyn l pht sng AM, FM Ni dung : Khi nim v tn hiu m tn, Cao tn, sng in t, Qu trnh iu ch sng AM v x l tn hiu i pht, u nhc im ca sng pht thanh AM, Qu trnh iu ch FM v x l pht sng FM, u v nhc im ca pht thanh trn sng FM 1. Nguyn l pht thanh trn sng AM a) Khi nim v tn hiu m tn ( Audio ) : Tn hiu m tn l tn hiu ca sng m thanh sau khi c i thnh tn hiu in thng qua Micro. Sng m thanh l mt dng sng c hc truyn trong khng gian, khi sng m thanh va chm vo mng Micro lm cho mng Micro rung ln, lm cho cun dy gn vi mng Micro c t trong t trng ca nam chm dao ng, hai u cun dy ta thu c mt in p cm ng => chnh l tn hiu m tn .
Micro i sng m thanh thnh tn hiu m tn (Audio) Tn hiu m tn c gii tn t 20Hz n 20KHz v khng c kh nng bc x thnh sng in t truyn trong khng gian, do truyn tn hiu m tn i xa hng trm, hng ngn Km. Ngi ta phi gi tn hiu m tn cn truyn vo sng cao tn gi l sng mang, sau cho sng mang bc x thnh sng in t truyn i xa vi vn tc nh sng.
[email protected]) Khi nim v tn hiu cao tn v sng in t. Tn hiu cao tn l cc tn hiu in c tn s trn 30KHz, tn hiu cao tn c tnh cht bc x thnh sng in t. Th d trn mt dy dn c tn hiu cao tn chy qua , th dy dn c mt sng gy can nhiu ra xung quanh, chnh l sng in t do dng in cao tn bc x ra khng gian. Sng in t : L sng truyn dn trong khng gian vi vn tc bng vn tc nh sng, c tn s t 30KHz n hng ngn MHz, cong ngi s dng sng in t trong cc lnh vc thng tin , v tuyn in , truyn thanh, truyn hnh, trong Radio l lnh vc truyn thanh chim gii tn t 30KHz n khong 16MHz vi cc sng iu ch AM, v t 76MHz n 130MHz vi cc sng iu ch FM. c) Qu trnh iu ch AM ( Amplitude Moducation : iu ch bin ) iu ch AM l qu trnh iu ch tn hiu tn s thp( nh tn hiu m tn, tn hiu video ) vo tn s cao tn theo phng thc => Bin i bin tn hiu cao tn theo hnh dng ca tn hiu m tn => Tn hiu cao tn thu c gi l sng mang.
Tn hiu vo v ra ca mch iu ch AM Tn hiu m tn c th ly t Micro sau khuch i qua mch khuch i m tn, hoc c th ly t cc thit b khc nh i Cassette, u a CD .. Tn hiu cao tn c to bi mch to dao ng, tn s cao tn l tn s theo quy nh ca i pht. Tn hiu u ra l sng mang c tn s bng tn s cao tn, c bin thay i theo tn hiu m tn. d) Qu trnh pht tn hiu i pht
Qu trnh pht sng Radio AM Tn hiu sau khi iu ch thnh sng mang c khuch i ln cng xut hng ngn Wat sau c truyn ra Anten pht . Sng in t pht ra t Anten truyn i trong khng gian bng vn tc ca nh sng, sng AM c th truyn i rt xa hng ngn Km v chng truyn theo ng thng, v cng c cc tnh cht phn x, khc x nh nh sng. e) ng truyn t i pht n my thu cch na vng tri t. Vi cc i pht xa cch chng ta na vng tri t nh i BBC pht t Anh Quc, sng in t truyn theo ng thng gp tng in ly chng phn x xung tri t ri li phn x ngc ln nhiu ln mi n c my thu, v vy tn hiu i ti my thu rt yu v sng khng n nh c th truyn tn hiu i xa, cc i pht thng pht bng sng ngn c tn s sng mang t 4 MHz n khong 23 MHz
ng truyn sng ca cc i pht xa my thu f) u v nhc im ca pht thanh trn sng AM u im : ca sng AM l c th truyn i xa ti hng nghn Km Nhc im : ca sng AM l d b can nhiu, di tn m thanh b ct sn do c im ca mch tch sng iu bin, do cht lng m thanh b hn ch. 2. Nguyn l pht thanh trn sng FM FM l vit tt ca ( Fryquency Moducation : iu ch tn s ) l iu ch theo phng thc lm thay i tn s ca tn hiu cao tn theo bin ca tn hiu m tn, khong tn s bin i l 150KHz Sng FM l sng cc ngn i vi tn hiu Radio, sng FM thng pht di tn t 76MHz n 108MHz a) Mch iu ch FM
iu ch FM ( Fryquency Moducation : iu ch tn s ) Vi mch iu ch tn s th sng mang c bin khng i, nhng tn s thay i theo bin ca tn hiu m tn, khi bin tn hiu m tn tng th tn s cao tn tng, khi bin m tn gim th tn s cao tn gim. Nh vy sng mang FM c tn s tng gim theo tn hiu
[email protected] tn v gii hn tng gim ny l +150KHz v -150KHz , nh vy tn s sng mang iu tn c di thng l 300KHZ. Th d nu i ting ni vit nam pht trn sng FM 100MHz th n truyn i mt di tn t 99,85 MHz n 100,15 MHz. b) Qu trnh pht sng FM Qu trnh pht sng FM tng t nh pht sng AM, sng mang sau khi iu ch cng c khuch i ri a ra An ten pht x truyn i xa c) u v nhc im ca sng FM . Sng FM c nhiu u im v mt tn s, di tn m thanh sau khi tch sng iu tn c cht lng rt tt, cho m thanh trung thc v c th truyn m thanh Stereo , sng FM t b can nhiu hn s vi sng AM. Nhc im ca sng FM l c ly truyn sng ngn, ch truyn c c ly t vi chc n vi trm Km , do sng FM thng c s dng lm sng pht thanh trn cc a phng. Nguyn l thu Radio AM, FM Ni dung : Nguyn l thu sng Radio AM, Phn tch s khi Radio bng AM, mch K trung tn AM, mch tch sng AM, Nguyn l thu sng bng FM, Phng php kim tra sa cha khi Radio. 1. Nguyn l thu sng Radio bng AM a) S khi ca Radio bng AM :
[email protected] khi mch Radio bng AM Bn a tr chut vo s xem ch thch. Xung quanh my thu thanh c v s cc sng in t t cc i pht khc nhau gi ti, nhim v ca my thu l chn ly mt tn s ri khuych i , sau tch sng ly ra tn hiu m tn. Mch thu sng Radio AM c cc mch nh sau : Mch cng hng v khuch i cao tn (RF Amply) thu tn hiu t mt i pht bng nguyn l cng hng, sau khuch i tn hiu cho mnh cung cp cho mch i tn . Mch dao ng ni ( OSC ) to dao ng cung cp cho mch i tn . Mch i tn ( Mixer ) trn hai tn hiu RF v tn hiu OSC to ra tn hiu trung tn IF, IF l tn hiu c tn s c nh bng 455KHz Mch khuch i trung tn ( IF Amply ) : Khuch i tn hiu IF ln bin ln cung cp cho mch tch sng . Mch tch sng ( Detect ) Tch tn hiu m tn ra khi sng mang cao tn .
b) Mch cng hng cao tn, dao ng ni v i tn.
Mch cng hng RF, dao ng OSC & i tn Mixer Bn a tr chut vo s xem ch thch. Ch thch : Mch cng hng cao tn (RF Amply) bao gm : T xoay C1 u song song vi cun dy L1 qun trn thanh ferit to thnh mnh mch dao ng LC, mch thu sng theo nguyn l cng hng, c rt nhiu sng mang c tn s khc nhau t cc i pht cng i ti my thu, khi tn s dao ng ca mch trng vi sng mang ca mt i pht th tn hiu sng mang ca i pht c cng hng v bin tng ln
[email protected] nhiu ln, tn hiu ny c thu vo thng qua cun th cp ca cun dy v c khuch i qua n Q1, sau a sang mch i tn, C1 l t xoay c th thay i gi tr, khi ta chnh nm Tuning chnh l chnh t xoay C1 lm tr s C1 bin i => tn s cng hng ca mch thay i . Mch OSC gm t xoay C2 u song song vi cun L2 to thnh mch dao ng, t xoay C2 c gn chung vi t C1 v hai t ny c chnh thay i gi tr ng thi, dao ng ni c tn s lun lun thp hn tn s cng hng RF mt lng khng i. Mch i tn : n Q2 lm nhim v i tn, tn hiu cao tn RF c a vo cc B, tn hiu dao ng ni c a vo cc E , tn hiu ly ra trn cc C gi l IF ( tn hiu trung tn) c gi tr khng i bng 455KHz IF = RF - OSC c) Mch chuyn bng Bng sng AM thng c chia ra lm hai hoc ba bng l - Bng sng trung MW c di tn t 526,5KHz n 1606,5KHz - Bng sng ngn 1 : SW1 c di tn t 2,3MHz n 7,3MHz - Bng sng ngn 2 : SW2 c di tn t 7,3MHz n 22MHz Di y l s mch chuyn bng, khi ta chuyn gia cc bng sng, t xoay s tip vo cc im c u vi cun dy c s vng dy khc nhau => lm cho tn s cng hng thay i.
Chuyn bng gia cc bng sng Radio AM d) Mch khuch i trung tn ( IF Amply)
Mch khuch i trung tn IF Amply a tr chut vo s xem ch thch Sau khi i tn, tn hiu IF c khuch i qua hai tng khuch i c cng hng, cc bin p trung tn T1, T2, T3 cng hng tn s 455KHz ng thi lm nhim v ni tng v phi hp tr khng . cc bin p ny c vt iu chnh nhm iu chnh cho bin p cng hng ng tn s . e) Mach tch sng AM
Mch tch sng AM Sau khi tn hiu IF c khuch i qua hai tng khuch i trung tn, tn hiu IF c a sang mch tch sng Mch tch sng bao gm Diode D1 tch ly bn k dng ca tn hiu sau c mch lc RC ( R1, C1, C2) lc b thnh phn cao tn , u ra ta thu c tn hiu m tn l ng bao ca tn hiu cao tn. Chnh mch lc RC ca mch tch sng AM loi b mt cc thnh phn tn s cao ca tn hiu m tn, do cht lng m thanh b gim.
[email protected]. Nguyn l thu sng Radio bng FM
Mch Radio s dng IC x l cho c hai bng sng AM (mu ) v FM( mu xanh) Bng sng FM c mch RF v OSC tng t bng sng AM , tuy nhin tn s ca bng FM cao hn rt nhiu bng sng AM v vy cc cun dy cng hng cho bng sng FM thng khng c li ferit, mch IF ca bng FM s dng thch anh cng hng tn s 10,7 MHz 3. Phng php sa cha khi Radio . Mt pan bnh c th kt lun hng tng Radio l thng thng m phn Casset vn hot ng bnh thng, khi chuyn sang Radio c th khng c ting hoc ting nh hoc khng thu c bng FM Cc bc sa cha khi Radio : Xc nh ng hin tng l h hng thuc khi Radio ( Thng thng sa mch Radio sau khi m bng casset c m thanh nhng Radio b hng ) Xc nh mch Vcc ( ng in p nui ) cho khi Radio : xc nh mch Vcc ta da vo t ho lc ngun to nht khu vc, ngun Vcc i qua cc dng ca t. Xc nh t xoay, cc thch anh cng hng trung tn cho bng FM.
nh chp khi Radio Bn a tr chut vo linh kin xem ch thch. Kim tra khi Radio: Trc khi sa khi Radio cn chc chn rng cc khi Equalizer, cng xut hot ng bnh thng ( nu Equalizer v cng xut tt th g tvit vo u vo khi Equalizer s c ting ra loa ) o Vcc cho khi Radio xem c 6V khng ? ( o trn t ho lc ngun to nht trong khu vc Radio) Nu c in p Vcc th g tvit vo chn t xoay xem c ting ku to loa khng. Nu g vo t xoay m c ting ku to loa th cn kim tra cun dy qun trn thanh ferit xem c b t khng, thay th cc thch anh 455MHz mch trung tn . Nu g vo t xoay m khng c ting ku ( c Vcc) th thng do hng IC.
Nu mt Vcc cho khi Radio , ta ln ngc theo mch in v pha chuyn mch Function kim tra, kim tra tr khng ca khi Radio bng cch o bng thang x1 vo hai u t lc, nu 1 chiu o ln kim, 1 chiu o khng ln kim => l tr khng bnh thng, c hai chiu kim ln = 0 l b chp, thng thng l chp IC, ( Hy xem li s cp in ca mch ngun) Nguyn tc ghi & pht bng Cassette Ni dung : Ngun tc ghi, xo v pht bng Cassette, Cu to v hot ng ca u t, Mch khuch i u t, Phng php kim tra v thay th u t 1. Tm lc cc nguyn tc hot ng ca Cassette a) Nguyn tc ghi bng Cassette
B c v bng t Bn a tr chut vo xem ch thch. H c ko bng trong hp cassette di chuyn vi tc u ngang qua hai u t, hai u t p st vo bng t, bng t di chuyn qua u xo trc ri mi qua u ghi. C hai loi u t xo l u xo bng nam chm vnh cu v u xo s dng dng cao tn xo, sau khi xo bng xong u ghi mi phng t thng ln mt bng t ho lp oxyt st v ghi bng di dng t d, u ghi trong qu trnh ghi cn nhn thm dng cao tn phn cc bng, mc ch lm cho tn hiu ghi khng b mo dng sinh ra sai ging.
a tr chut vo s xem ch thch
[email protected] khuch i u t ch ghi m t Micro, tn hiu t Micro i qua chuyn mch ghi v c khuch i qua tng Head Amply sau i qua chuyn mch Function tip nhn thm tn hiu t Radio, sau vng tr li qua chuyn mch ghi a v u t Ghi/c ghi ln bng t.
Minh ho qu trnh ghi bng t Micro b) Nguyn tc pht bng
a tr chut vo s xem ch thch Bng ghi, trn mt bng b t ho s gm nhng nam chm nh li ti xp nm ni tip nhau, khi pht bng nhng nam chm phng t thng vo khe st ca u c, t thng tp trung vo li st non ca u t to ra trn cun dy sc in ng cm ng tc l tn hiu m tn, tn hiu ny i qua chuyn mch ghi vo tng khuch i u t v qua cc tng Equalizer, khuch i cng xut ri a ra loa. c) Nguyn tc xo bng.
[email protected] th xo bng ( lm mt cc vt t ho trn mt bng) theo ba cch Dng mt nam chm vnh cu lm u xo . Dng in mt chiu a vo cun dy ca u xo. Dng dng cao tn t 30KHz n 160KHz a vo u xo.
2. u t v mch khuch ai u t ( Head & Head Amply)
Cu to ca u t C 3 loi u t : Ghi - Pht v u t xo , nhng cu to th ging nhau cng gm Cun dy, li st non v khe st m ng cho t thng vo hoc ra khi li st. u ghi v u pht thng chung nhau, ring u xo phn bit vi u ghi - pht do b rng khe st rng hn.
Nguyn l hot ng ca u t Mch khuch i u t :
Hnh dangh thc t
Mch khuch i u t Tn hiu c ra t u t thng rt yu cn c khuch i nng bin ln ln trc khi a sang tng K cng xut, mch khuch i u t c th s dng hai n 3 tng K bng Transistor, hoc s dng IC, mch K u t lm hai nhim v : Ki tn hiu t u t trong qu trnh pht bng v Ki tn hiu t Micro trong qu trnh ghi m. 3. H hng thng gp ca u t v mch khuch i u t . u t mn : Sau mt thi gian s dng khong 1000 gi pht bng th u t ht tui tho do b mi mn bi bng t trong qu trnh pht bng, biu hin ta thy trn b mt u t mn thnh mt dnh rng bng si bng, khi pht bng m thanh nh v trm, khi ta cn thay mt u t mi.
Thay u t : Hin nay c rt nhiu loi u t khc nhau, tt nht khi mua u t bn nn mang theo u t c so snh, hoc bn nh chng loi my . Khi thay u t, bn cn chnh li c chnh phng v, l c bt u t c m l so, sau khi thay bn m cho bng chy v chnh li c phng v thu c ting nghe thanh nht. Hng tng khuch i u t : Khi kim tra tng khuch i u t, bn cn kim tra cc tng pha sau trc v chc chn rng t tng Equalizer hot ng tt. Bt Play v g vo chn u t, nu c ting to loa l tng khuch i u t vn bnh thng, nu khng c ting l hng tng khuch i u t.
[email protected] tng khuch i u t : - Dng xng hoc du RP7 lau chuyn mch ghi - Kim tra ngun Vcc cho tng K u t ( o trn t lc ) - Thay IC K u t ( nu c ) B c v M t ko bng Ni dung : Cc chi tit trn b c Cassette, Phng php kim tra v sa cha b c, M t v mch n tc, phng php kim tra v thay th m t 1. B c v m t. a) Cc chi tit trn b c a tr chut vo cc chi tit xem ch thch
Pha trc b c a tr chut vo cc chi tit xem ch thch
b) Cc h hng thng gp ca b c . Bnh 1 : My c in vo, Radio vn hot ng, m bng khng quay Nguyn nhn : Hng M t t dy culoa Cng tc trn b c khng tip xc
Khc phc : Kim tra v thay dy culoa nu b trng o in p cp cho M t, nu c in m m t khng quay th thay m t. Kim tra v lm v sinh cng tc trn b c nu khng c ngun cp vo Mt
Bnh 2 : Bng thng xuyn b ri, hoc trc thu bng khng quay Nguyn nhn : t hoc b trng dy culoa ph ko bnh trung gian Bnh rng trong gian b mn, b st mt s rng hoc b d
Khc phc : Kim tra v thay dy culoa ph ko trc qun bng Kim tra v thay cc bnh rng trung gian
Bnh 3 : Ting b mo nghe d r lc nhanh lc chm Nguyn nhn:
[email protected] Mt b hng mch n tc Dy culoa b trng Bnh t p bng b kt
Khc phc : Kim tra v thay cc dy culoa Kim tra v thay bnh t cao su Thay M t ny dy culoa v bnh t tt.
Bnh 4 : Bng b nh qun mp Nguyn nhn : Bnh t cao su b trai khng cn s n hi
Khc phc : Lau sch b mt bnh t cao su bng cn Thay bnh t cao su mi
Bnh 5 : m thanh nghe trm v nh Nguyn nhn : u t c b bn , hoc u t c b mn. u t chnh sai c phng v
Khc phc : Lau sch u t bng cn nu bn Chnh li c phng v ( c bt u t c l so ) Thay u t mi.
2) M t v mch n tc. - M t l ng c ko bng trong qu trnh Play v tua i tua li - Hin nay c nhiu loi 6V, 9V , 12V , M t quay ngc k hiu trn thn ch L, m t quay thun k hiu ch R. - Khi thay m t bn cn thay ng in p v ng chiu quay. - Chnh li c chnh tc pha sau M t nu tc quay cha ng. Mch n tc Mch n tc c nhim v gi cho tc quay bng khng i trong qu trnh Play, mch n tc c gn sau m t, tc m t ph thuc vo in p cung cp cho mt, v vy mch n tc chnh l mch n p tuyn tnh.
Mch n tc cho m t. Q1 l n cng xut Q2 l n s sai R1 v Dz to ra p chun a vo chn E R2 v VR1 to ra p ly mu VR1 l bin tr chnh tc Hng Mt ch yu l do hng mch n tc, biu hin l bng quay nhanh nh tua v chnh tc khng tc dng hoc bng khng quay mc d ngun cung cp c.
Nguyn l hot ng ca mch n tc tng t nguyn l hot ng ca mch n p tuyn tnh.( Xem li phn mch n p Thc hnh lp rp Cassette Ni dung : Hng dn chi tit cc bc lp hon chnh mt chic Cassette n gin, S mch v cc thng s linh kin, a ch mua linh kin ng gi T lp Cassette Bn c hy t lp mt chic Cassette theo s mch di y, sau khi lp thnh cng bn s t rt ra cho mnh c nhiu kinh nghim b ch. S mch di y tc gi lp v chy th nghe rt hay, nu bn lp m m thanh nh hoc b d th cn i chiu li vi s cho chnh xc gi tr cc linh kin, tng gi thnh ca mch ht khong 50.000VN (cha k loa v bng th) Sau khi lp xong , nu bn thay u t bng mt chic Micro th bn s c mt chic tng m nho nh, v bn cng hiu rng Amply cng xut ln cng c nguyn l tng t, ch khc l ngun cung cp cao hn, tng cng xut lp cc n c cng xut ln hn m thi.
S Cassette n gin - Ngun 12V DC Bn a tr chut vo s bt thm thng tin Bng thng s v gi thnh cc linh kin ca s mch trn
K hiu Q1 Q2 Q3 Q4 Q5
Tn linh kin / Tr s Transistor C828 Transistor C828 Transistor C828 Transistor B562 Transistor D468
Gi tin VN 300 300 300 1.000 1.000
[email protected] R2 R3 R4 R5 R6 R7 R8 R9 R10 R11 VR1 D1 D2 D3 C1 C2 C3 C4 C5 C6 C7 in tr 1,5 K in tr 3,3 K in tr 100 K in tr 470 K in tr 4,7 K in tr 100 K in tr 470 K in tr 4,7 K in tr 470 in tr 100 in tr 100 K Trit p 50 K Cu Diode dt Diode tch sng Diode tch sng T ho 2200F/25V T ho 100F/16V T ho 4,7 F T ho 4,7 F T ho 4,7 F T ho 4,7 F T ho ra loa 470 F/16V 30 30 30 30 30 30 30 30 30 30 30 1.000 1.000 200 200 1.500 500 200 200 200 200 800
[email protected] p B c Mch in Khc Bin p ngun 1A B c c sn u t v mt Mch in hn linh kin Thic hn + dy ni Tng cng Tng cng ht nm mi ngn ng 14.000 21.000 2.000 3.000 50.000 VN
