Philips-CDR-775-Service-Manual-2电路原理图.pdf

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1、Faultfinding Guide GB 59CDR779 8.8.2 Circuit description of the current mode power supply8.2.1 BlockdiagramFigure 8-10 8.2.2 Function descriptionMOSFET 7125 is used as a power switch controlled by the controller IC 7110. When the switch is closed, energy is transferred from mains to the transformer.

2、 This energy is supplied to the load when the switch is opened. Through control of the switched-on time, the energy transferred in each cycle is regulated so that the output voltages are independent of load or input voltage variations. The controlling device UC3842 is an integrated pulse width modul

3、ator. A clock signal initiates power pulses at a fixed frequency. The termination of each output pulse occurs when a feedback signal of the inductor current reaches a threshold set by the error signal. In this way the error signal actually controls the peak inductor current on cycle-by cycle basis.8

4、.2.3 Description of UC3842The input voltage Vcc(pin 7) is monitored by a comparator with hysteresis, enabling the circuit at 16V and disabling the circuit below 10V. The error amplifier compares a voltage Vfb(pin 2) related to the output voltage of the power supply, with an internal 2.5V reference.

5、The current sense comparator compares the output of the error amplifier with the switch current Isense(pin 3) of the power supply. The output of the current sense comparator resets a latch, which is set every cycle by the oscillator. The output stage is a totem pole, capable of driving a MOSFET dire

6、ctlyFigure 8-11 8.2.4 Start up sequencet1: Charging the capacitor at VccC2129 wiil be charged via R3123 and R3134, C2133 and C2111 via R3129. The output is switched off During t1.t2: Charging of output capacitorsWhen the input voltage of the IC exceeds 14,5V, the circuit is enabled and starts to pro

7、duce output pulses. The current consumption of the circuit increases to about 17mA, depending on the external loads of the IC. At first, the 7201713162206250624062306210513171252643StartProtectionOvervoltageREGULATIONEMIFILTERMAINS+5V+5V+12V+12V-8VVFTDVDC2VDC10VRQSCLOCK+-VsenseRsensevt2.5VErrorAmpli

8、fierVerrorPWMcomparatorlatchVccVccOutputIsenseCompVfbLightningProtectionRectifierCircuitCONTROL2579CL 06532151_018.eps271100Figure B : Blockdiagram UC3842682.5VERROR AMP I SENSE COMPSR7516V4OSCRt/ctGNDVI2VfbCOMPOUTPUTVref1LATCHI sense132RR1V-+-+6V+BIASS/R5V2.5VREFCL 06532151_019.eps271100Faultfindin

9、g GuideGB 60 CDR7798.capacitor at the Vcc pin will discharge because the primairy auxiliary voltage, coming from winding7-9 is below the Vcc voltage. At some moment during t2, the primary auxiliary voltages reaches the same level as Vcc.This primary auxiliary voltage now determines the Vcc voltaget3

10、: regulationThe output voltage of the power supply is in regulationt4: overloadWhen the output is shortened, the supply voltage of the circuit will decrease and after some time drop below the lower threshold voltage. At that moment, the output will be disabled and the process of charging the Vcc cap

11、acitor starts again. If the output is still shorted at the next t2 phase, the complete start-and stop sequence will repeat. The power supply comes in a hiccup mode.Figure 8-12 8.2.5 RegulationFigure 4 shows the most relevant signals during the regulation phase of the power supply.The oscillator volt

12、age ramps up and down between V1 and V2. The voltage at the current sense terminal is compared every cycle with the output of the error amplifier Vcomp. The output is switched off when the current sense level exceeds the level at the output of the error amplifier.TimeON phase : A drain current will

13、flow from the positive supply at pin 1 through the transformers primary winding, the MOSFET and Rsense to ground. As the positive voltage at pin 1 of the transformer is constant, the current will increase linearly and create a ramp dependent on the mains voltage and the inductance of the primary win

14、ding. A certain amount of energy is stored in the transformer in the form of a magnetic field. The polarity of the voltages at the secundary windings is such that the diodes are non-conducting.TimeDIODE phase : When the MOSFET is switched off, energy is no longer supplied to the tranformer. The indu

15、ctance of the tranformer now tries to maintain the current which has been flowing through it at a constant level. The polarity of the voltage from the transformer therefore becomes reversed. This results in a current flow through the tranformers secondary winding via the diodes, electrolytic capacit

16、ors and the load. This current is also ramp shaped but decreasing.TimeDEAD phase : when the stored energy has been supplied to the load, the voltage from the secondary windings falls below the output voltage(held constant by the electrolytic capacitors) plus the threshold voltage of the diodes. The

17、current in the secondary winding stops flowing. At this point, the drain voltage of the MOSFET is not yet zero because C2609 between drain and source contains a certain charge. This charge will start a sine-shaped ringing together with the transformers self-induction. The oscillator will start a nex

18、t cyclus which consists of the described three phases. The time of the different phases depends on the mains voltage and the load.TimeDEAD is maximum at an input of 400VDC and minimum load, it will be zero at an input of 100VDC and overload.Figure 8-13 Figure C : Start-up sequence1mAt1Vo0OUTPUTt2 t3

19、 t4shortVccVc2134Icc20mA0V10V16V12VCL 06532151_020.eps271100VoscIdiodesVgateVdrainIdrainVsenseVcomp0V2V1Ton Tdiode TdeadCL 06532151_021.eps271100Faultfinding Guide GB 61CDR779 8.8.2.6 OscillogramsFigure 8-14 8.2.7 Circuit descriptionInput circuitThe input circuit consists of a lightning protection c

20、ircuit and an EMI filter.The lightning protection comprises R3120, gasarrestor 1125 and R3124.The EMI filter is formed by C2120, L5120, C2125 and R3124. It prevents inflow of noise into/from the mains.Primary rectifier/smoothing circuitThe AC input is rectified by rectifier bridge 6102 and smoothed

21、into C2121. The voltage over C2121 is approximately 300V. It can vary from 100V to 390V.Start circuit and Vcc supplyThis circuit is formed by R3123, R3134, C2129, D6129, R3129, R3111, C2133 and C2111.When the power plug is connected to the mains voltage, the stabilised voltage over D6129(24V) will c

22、harge C2133 via R3129. When the voltage reaches 14,5V across C2111, the control circuit of IC7110 is turned on and the regulation starts. During regulation, Vcc of IC7110 will be supplied by the rectified voltage from winding 7-9 via L5132, D6132 and C2133.Control circuitThe control circuit exists o

23、f IC7110, C2102, C2104, C2107, C2109, C2110, R3102, R3103, R3104, R3107, R3108, R3109 and R3110. C2102 and R3110 define the frequency of the oscillator.Power switch circuitThis circuit comprises MOSFET 7125, Rsense 3126, 3127 and 3128, R3125, C2127, L5125, R3112 and R3113. R3125 is a pull-down resis

24、tor to remove static charges from the gate of the MOSFET.Regulation circuitThe regulation circuit comprises opto-coupler 7200 which isolates the error signal from the control IC on the primary side and a reference component 7201. The TL431(7201) can be represented by two components: a very stable an

25、d accurate reference diodea high gain amplifierFigure 8-15 TL431 will conduct from cathode to anode when the reference is higher than the internal reference voltage of about 2.5V. If the reference voltage is lower, the cathode current is almost zero.The cathode current flows through the LED of the o

26、pto-coupler. The collector current of the opto-coupler flows through R3106, producing an error voltage, connected to voltage feedback pin 14 of IC7110.Overvoltage protection circuitThis circuit consist of D6114, C2114, R3115and R3116.OscillogramsPM3394Bch2ch3ch1CH1 2CH2CH3 2 V ALT MTB5.00us- 0.90dv

27、ch1-123Tch1 : Drain voltagech2 : Drain currentch3 : Gate voltagePM3394Bch3ch1CH1 1CH3 50mV ALT MTB5.00us- 0.90dv ch1-13Tch1 : Drain voltagech2 : Oscillator voltagePM3394Bch3ch1CH1 1CH3 20mV ALT MTB5.00us- 0.90dv ch1-13Tch1 : Drain voltagech3 : Sense voltageCL 06532151_022.eps301100A2.5VRKCL 06532151

28、_023.eps271100Faultfinding GuideGB 62 CDR7798.When the regulation circuit is interrupted due to an error in the control loop, the regulated output voltage will increase (overvoltage). This overvoltage is sensed on the primary winding 7-9. When an overvoltage longer than 2.0s is detected, the output

29、is disabled until Vcc is removed and then re-applied. The power supply will come in a hiccup mode as long as the error in the control loop is present.Secondary rectifier/smoothing circuitThere are 5 rectifier/smoothing circuits on the secondary side. Each voltage depends on the number of windings of

30、 the transformer. The -8V supply is regulated by voltage regulator 7249.On/off circuitIn off mode pin 1 and pin 2 of connector 0206 are connected. The high voltage (-8V, +12V) over opto coupler 7200 forces this one to conduct . IC 7110 is switched off8.2.8 Troubleshooting PSU CDR3-ECOFigure 8-16 Fau

31、ltfinding diagramTROUBLE SHOOTING POWER SUPPLYpower supply OKCheck DC voltages+5V +12V -8V VFTD(-38V) VDC1-VDC2(3V8)OKYESYES5V OK5V NOKNOKNOKNOKNOKOKNOKNOKDisconnect the power supply from the MAIN BoardConnect a dummy load resistor 6,8 ohm 10W (min 5W)on the 5V andpower supply OKcheck - main board-

32、front board- modem boardOKNONO (Vsource = +- 0.8V)OKOKOKOKCheck the +5Vcheck 6210-2210-2253-5210check the fault voltage pathconnect the mains inlet to a mainsisolated variacturn input voltage up and check acrossC2121 the voltagethis voltage should be +/- 1,41 x Vin accheck the functionality of the f

33、ollowing components:1120-2121-2125-2126-2127-6102-7125check oscillator on pin 4 IC7110is the osc +- 30kHz working ?check Vcc on pin 7 IC7110Vcc = 12V. 16Vis power supply ticking?check the load on the secundairy outputcheck overload circuit 6141-7141-7150check 2121-2133-2134-3123-3134-6130-6132replac

34、e 7110check:3201-3202-3203-3204-32053206-3207-3208-7131-7201replace 7110check circuit around Ic7110check 3125-3126-3127-3128replace 7125check 2102 - 3102replace 7110check the voltage on the source of 7125Vsource = 1,3V ?Disconnect diode 6150start variac from 0V and turn-up slowlymeasure the 5V outpu

35、tIf the 5V becoming higher than 5V, the regulatorcircuit are damagedAfter the power repaired check the 3,3VCheck DC voltages+5V +12V -8V VFTD(-38V) VDC1-VDC2(3V8)CL 06532151_024.eps271100GB 36CDR779 5.Block diagrams, Circuit diagrams and PWBsPSU CDR3-ECUVVF213 B12F214 B12F215 E7F216 F7F217 G7F218 G7

36、F219 G7F220 B11F221 B11F222 B11F223 A9F224 A10F230 A107253 D97254 D97260 B99122 A4F100 A2F101 A2F102 B2F103 B2F104 A5F105 A6F106 A6F107 B6F108 B4F109 D3F110 E5F111 B6F112 B6F121 D2F122 F3F125 D4F201 A9F202 A9F203 B10F204 B10F205 C9F206 C9F207 C11F208 C12F209 D11F210 D11F211 E10F212 E115226 E95230 B1

37、05240 C95250 C115255 C76100 A46101 A56102 A56106 B46107 C46129 D46130 D56132 D66133 E56141 E26150 F36201 C106202 D106210 A86220 D86230 B86240 C86250 C87110 E57125 B67131 F67141 F37150 F37201 G77249 B87251 C107252 C103142 E23150 F23151 F33201 E73202 F83203 F73204 F83205 F83206 G83207 F73208 F73220 D1

38、13221 E103222 D103223 E93224 D93225 C93229 C113230 B83232 C113233 D113234 D103235 B103236 C115120 A45121 A45125 B65130 D65131 A65210 A95220 D115225 D92232 B92234 B92240 C82242 C92243 C92250 D82252 C112253 A82260 A103102 F53103 E53104 E43105 F43106 F43109 G43110 D53111 D43112 D63113 E53117 A33119 B33

39、120 A23122 A43123 B43124 A43125 C53126 C63127 C63128 C63129 D43134 C43141 E30260 A71120 B22102 G42104 E42106 F32109 G42111 G52119 A32120 A32121 B62125 A52126 B52127 C62128 A52129 D32130 D62131 A72133 D52134 D52141 E32142 E42150 F22161 G52201 E72202 F72210 A82213 A92220 D82221 E72222 D102230 B82231 B

40、9345678910112ABCDEFGHABCDEFGH0101 A20125 B50205 A120206 G70207 A110208 A10USAReservedCU15D3ReservedReserved ReservedReservedJumper47u31229122512051212121 100u 220uCU15D3UF1922P1234567891011212F1082R7ReservedJumper*: Reserved Item Numbershould be YK typeBZX84-C2468uEuro WW0101 Unpolarized Unpolarized

41、 PolarizedF102HEATSINK012531271R-8Vr1K53150470R3124F101HCS0528010112314110K+12V0208F10510K311032023K3100n21613119F112F2242n221311K23222F216F21368R322510R31427253BC327-25F223F2031243F214F218UF1922P45120Vfb8Vref2232UC3842A71101COMP5GND3Isense6OUTPUT4RtCt7VCC2F1215130+5Vr6101BZX79-C15BZX79-C15610032011

42、0R2240 220u3K3323531091K390R3223BYD33D62204u721290260HEATSINK+12Vr100u21332142 100n226010nF125311222R22u2234+12V32071K680K3117BYD33D2242 100u624032063K3F2041n82102+5V222147nF12231061K100u2134VDC2100n215021262n27141BC857B72602GND1IN3OUT3128 1R5315156K470R3208VFTDVFTDSB3606210UDZ-20B61413113 270R22312

43、120 220n+12V33n212852106u82u25230232259331206230BYW98-2002213VDC252264u7UDZ-22B6201VDC1330p2109F2301N40066107470p21276250BYD33JF10623456F104F209EH-B02071F215F202F21022301m+5Vr7201TL431CLP2131n21042210 2m2F1033123 18K+5V1SS35561307125STP3NB60FP6150UDZ-4.7B311168R2201 100n310415K2253F221220222nF205310

44、333R3203 100R7131CQY80NG2130225210uF206F2192250 100u7150BC847B-8VBC857B7252512583R323632301K2119522010u100u2222UDZ-2.7B6202111314151617182579F2125131CT283D310F110+12Vr-8VrF21112K3232+5V31222R710K2121 100uF111312932211K2F2225K632294n7210618K31347254BC847BVDC1-8V+5V22437249L7908GND1IN2OUT3312510K52501

45、0u61331SS355-8VT2.0A H 250V1120524010u31261R9122F2083205 220R310222K32203452254u768R3224F1075121CU15D31 2310515KF220122111 100nF1000206EH-B10KBYD33D61322n2212532043K33234F217F201S1NB8061024312470R52551uF207323361061N40062u22141T2220 330uBC337-407251F109110112345678961290205EH-BPOWER SUPPLY UNIT CDR3

46、-ECOCL 06532151_013.eps241100Block diagrams, Circuit diagrams and PWBs GB 37CDR779 5.Layout PSU CDR3-ECOPOWER SUPPLY UNIT CDR3-ECO - TOP VIEWPOWER SUPPLY UNIT CDR3-ECO - BOTTOM VIEWCL 06532151_014.eps241100Spare parts list GB 77CDR779 10.Headphone boardc1032100 4822 126 14585 100nF 10% 50V2101 4822

47、124 81151 22F 50V2102 4822 126 14585 100nF 10% 50V2103 4822 124 81151 22F 50V2104 5322 126 10511 1nF 5% 50V2105 5322 126 10511 1nF 5% 50Vc1023100 5322 117 11726 10 5%3101 5322 117 11726 10 5%3102 4822 051 20008 0 jumper . (0805)3104 4822 051 20008 0 jumper . (0805)3106 4822 117 11503 220 1% 0.1W3107

48、 4822 117 11503 220 1% 0.1W3108 4822 051 20122 1k2 5% 0.1W3109 4822 051 20122 1k2 5% 0.1Wc99c1017102 4822 209 82362 NJM4556D7103 4822 130 42615 BC817-407104 4822 130 42615 BC817-40PSU CDR3 ECOMiscellaneous0025 4822 492 63524 FIX. TRANSISTOR0060 4822 492 63524 FIX. TRANSISTOR0101c104 4822 265 31015 H

49、SC05281120c104 4822 070 32002 218002.(2A)1121 4822 265 11253 FUSE HOLDER 2Pc1032102 2238 861 15182 50V 1N8 PM5 R2104 5322 122 31647 1nF 10% 63V2106 5322 126 10223 4.7nF 10% 63V2109 5322 122 31863 63V 330pF PM52111 4822 126 14585 100nF 10% 50V2120c104 4822 121 10697 220nF 20% 275V2121 8222 675 05480 EL 47F /400V YK KC RUBYCOnF2127 4822 122 50116 470pF 10% 1KV2128 4822 121 70141 33nF 5% 400V2129 4822 124 40769 4.7F 20% 100V2131c104 4822 126 14497 2.2nF 20% 250V2133 4822 124 42084 100F 20% 35V2134 4822 124 42084 100F 20% 35V2141 4822 1