Philips-CDR-775-Service-Manual-2 电路图 维修手册.pdf

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1、Faultfinding GuideGB 59CDR7798. 8.2Circuit description of the current mode power supply 8.2.1Blockdiagram Figure 8-10 8.2.2Function description MOSFET 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 modula

3、tor. 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、.2.3Description of UC3842 The 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、ctly Figure 8-11 8.2.4Start up sequence t1: Charging the capacitor at Vcc C2129 wiil be charged via R3123 and R3134, C2133 and C2111 via R3129. The output is switched off During t1. t2: Charging of output capacitors When the input voltage of the IC exceeds 14,5V, the circuit is enabled and starts to

7、 produce output pulses. The current consumption of the circuit increases to about 17mA, depending on the external loads of the IC. At first, the 7201 7131 6220 6250 6240 6230 6210 5131 7125 2643 Start Protection Overvoltage REGULATION EMI FILTER MAINS +5V +5V +12V +12V -8V VFTD VDC2 VDC1 0V RQ S CLO

8、CK + + - - Vsense Rsense v t2.5V Error Amplifier Verror PWM comparator latch Vcc Vcc Output Isense Comp Vfb Lightning Protection Rectifier Circuit CONTROL 2 5 7 9 CL 06532151_018.eps 271100 Figure B : Blockdiagram UC3842 6 8 2.5V ERROR AMPI SENSE COMP S R 7 5 16V 4 OSCRt/ct GND VI 2 Vfb COMP OUTPUT

9、Vref 1 LATCH I sense 1 3 2R R1V - + + - - + 6V + BIAS S/R 5V 2.5V REF CL 06532151_019.eps 271100 RadioFans.CN 收音机爱 好者资料库 Faultfinding GuideGB 60CDR7798. capacitor at the Vcc pin will discharge because the primairy auxiliary voltage, coming from winding7-9 is below the Vcc voltage. At some moment dur

10、ing t2, the primary auxiliary voltages reaches the same level as Vcc. This primary auxiliary voltage now determines the Vcc voltage t3: regulation The output voltage of the power supply is in regulation t4: overload When the output is shortened, the supply voltage of the circuit will decrease and af

11、ter some time drop below the lower threshold voltage. At that moment, the output will be disabled and the process of charging the Vcc capacitor 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

12、. Figure 8-12 8.2.5Regulation Figure 4 shows the most relevant signals during the regulation phase of the power supply. The oscillator voltage 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 outp

13、ut is switched off when the current sense level exceeds the level at the output of the error amplifier. TimeON phase : A drain current will 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 transf

14、ormer is constant, the current will increase linearly and create a ramp dependent on the mains voltage and the inductance of the primary winding. 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 th

15、at the diodes are non-conducting. TimeDIODE phase : When the MOSFET is switched off, energy is no longer supplied to the tranformer. The inductance 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 transfor

16、mer therefore becomes reversed. This results in a current flow through the tranformers secondary winding via the diodes, electrolytic capacitors 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

17、secondary windings falls below the output voltage(held constant by the electrolytic capacitors) plus the threshold voltage of the diodes. The 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

18、 a certain charge. This charge will start a sine-shaped ringing together with the transformers self-induction. The oscillator will start a next 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 i

19、nput of 400VDC and minimum load, it will be zero at an input of 100VDC and overload. Figure 8-13 Figure C : Start-up sequence 1mA t1 Vo 0 OUTPUT t2t3t4 short Vcc Vc2134 Icc 20mA 0V 10V 16V 12V CL 06532151_020.eps 271100 Vosc Idiodes Vgate Vdrain Idrain Vsense Vcomp 0 V2 V1 TonTdiode Tdead CL 0653215

20、1_021.eps 271100 RadioFans.CN 收音机爱 好者资料库 Faultfinding GuideGB 61CDR7798. 8.2.6Oscillograms Figure 8-14 8.2.7Circuit description Input circuit The input circuit consists of a lightning protection circuit and an EMI filter. The lightning protection comprises R3120, gasarrestor 1125 and R3124. The EMI

21、filter is formed by C2120, L5120, C2125 and R3124. It prevents inflow of noise into/from the mains. Primary rectifier/smoothing circuit The AC input is rectified by rectifier bridge 6102 and smoothed into C2121. The voltage over C2121 is approximately 300V. It can vary from 100V to 390V. Start circu

22、it and Vcc supply This 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 charge C2133 via R3129. When the voltage reaches 14,5V across C2111, the control circuit of IC7110

23、 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 circuit The control circuit exists of IC7110, C2102, C2104, C2107, C2109, C2110, R3102, R3103, R3104, R3107, R3108, R3109 and R3110

24、. C2102 and R3110 define the frequency of the oscillator. Power switch circuit This circuit comprises MOSFET 7125, Rsense 3126, 3127 and 3128, R3125, C2127, L5125, R3112 and R3113. R3125 is a pull-down resistor to remove static charges from the gate of the MOSFET. Regulation circuit The regulation c

25、ircuit 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 and accurate reference diode a high gain amplifier Figure 8-15 TL431 will conduct from cathod

26、e 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 opto- coupler. The collector current of the opto-coupler flows through R3106, producing a

27、n error voltage, connected to voltage feedback pin 14 of IC7110. Overvoltage protection circuit This circuit consist of D6114, C2114, R3115and R3116. Oscillograms PM3394B ch2 ch3 ch1 CH1 2 CH2 CH3 2 V ALT MTB5.00us- 0.90dv ch1- 1 2 3 T ch1 : Drain voltage ch2 : Drain current ch3 : Gate voltage PM339

28、4B ch3 ch1 CH1 1 CH3 50mV ALT MTB5.00us- 0.90dv ch1- 1 3 T ch1 : Drain voltage ch2 : Oscillator voltage PM3394B ch3 ch1 CH1 1 CH3 20mV ALT MTB5.00us- 0.90dv ch1- 1 3 T ch1 : Drain voltage ch3 : Sense voltage CL 06532151_022.eps 301100 A 2.5V R K CL 06532151_023.eps 271100 RadioFans.CN 收音机爱 好者资料库 Fau

29、ltfinding GuideGB 62CDR7798. 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 is disabled until

30、 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 circuit There are 5 rectifier/smoothing circuits on the secondary side. Each voltage depends on the number of windings of the transforme

31、r. The -8V supply is regulated by voltage regulator 7249. On/off circuit In 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 off 8.2.8Troubleshooting PSU CDR3-ECO Figure 8-16 Faultfinding di

32、agram TROUBLE SHOOTING POWER SUPPLY power supply OK Check DC voltages +5V +12V -8V VFTD(-38V) VDC1-VDC2(3V8) OK YES YES 5V OK 5V NOK NOK NOK NOK NOK OK NOK NOK Disconnect the power supply from the MAIN Board Connect a dummy load resistor 6,8 ohm 10W (min 5W) on the 5V and power supply OK check - mai

33、n board - front board - modem board OK NO NO (Vsource = +- 0.8V) OK OK OK OK Check the +5V check 6210-2210-2253-5210 check the fault voltage path connect the mains inlet to a mains isolated variac turn input voltage up and check across C2121 the voltage this voltage should be +/- 1,41 x Vin ac check

34、 the functionality of the following components: 1120-2121-2125-2126-2127-6102-7125 check oscillator on pin 4 IC7110 is the osc +- 30kHz working ? check Vcc on pin 7 IC7110 Vcc = 12V. 16V is power supply ticking? check the load on the secundairy output check overload circuit 6141-7141-7150 check 2121

35、-2133-2134-3123-3134-6130-6132 replace 7110 check:3201-3202-3203-3204-3205 3206-3207-3208-7131-7201 replace 7110 check circuit around Ic7110 check 3125-3126-3127-3128 replace 7125 check 2102 - 3102 replace 7110 check the voltage on the source of 7125 Vsource = 1,3V ? Disconnect diode 6150 start vari

36、ac from 0V and turn-up slowly measure the 5V output If the 5V becoming higher than 5V, the regulator circuit are damaged After the power repaired check the 3,3V Check DC voltages +5V +12V -8V VFTD(-38V) VDC1-VDC2(3V8) CL 06532151_024.eps 271100 GB 36CDR7795.Block diagrams, Circuit diagrams and PWBs

37、PSU CDR3-ECU V V F213 B12 F214 B12 F215 E7 F216 F7 F217 G7 F218 G7 F219 G7 F220 B11 F221 B11 F222 B11 F223 A9 F224 A10 F230 A10 7253 D9 7254 D9 7260 B9 9122 A4 F100 A2 F101 A2 F102 B2 F103 B2 F104 A5 F105 A6 F106 A6 F107 B6 F108 B4 F109 D3 F110 E5 F111 B6 F112 B6 F121 D2 F122 F3 F125 D4 F201 A9 F202

38、 A9 F203 B10 F204 B10 F205 C9 F206 C9 F207 C11 F208 C12 F209 D11 F210 D11 F211 E10 F212 E11 5226 E9 5230 B10 5240 C9 5250 C11 5255 C7 6100 A4 6101 A5 6102 A5 6106 B4 6107 C4 6129 D4 6130 D5 6132 D6 6133 E5 6141 E2 6150 F3 6201 C10 6202 D10 6210 A8 6220 D8 6230 B8 6240 C8 6250 C8 7110 E5 7125 B6 7131

39、 F6 7141 F3 7150 F3 7201 G7 7249 B8 7251 C10 7252 C10 3142 E2 3150 F2 3151 F3 3201 E7 3202 F8 3203 F7 3204 F8 3205 F8 3206 G8 3207 F7 3208 F7 3220 D11 3221 E10 3222 D10 3223 E9 3224 D9 3225 C9 3229 C11 3230 B8 3232 C11 3233 D11 3234 D10 3235 B10 3236 C11 5120 A4 5121 A4 5125 B6 5130 D6 5131 A6 5210

40、A9 5220 D11 5225 D9 2232 B9 2234 B9 2240 C8 2242 C9 2243 C9 2250 D8 2252 C11 2253 A8 2260 A10 3102 F5 3103 E5 3104 E4 3105 F4 3106 F4 3109 G4 3110 D5 3111 D4 3112 D6 3113 E5 3117 A3 3119 B3 3120 A2 3122 A4 3123 B4 3124 A4 3125 C5 3126 C6 3127 C6 3128 C6 3129 D4 3134 C4 3141 E3 0260 A7 1120 B2 2102 G

41、4 2104 E4 2106 F3 2109 G4 2111 G5 2119 A3 2120 A3 2121 B6 2125 A5 2126 B5 2127 C6 2128 A5 2129 D3 2130 D6 2131 A7 2133 D5 2134 D5 2141 E3 2142 E4 2150 F2 2161 G5 2201 E7 2202 F7 2210 A8 2213 A9 2220 D8 2221 E7 2222 D10 2230 B8 2231 B9 3456789101112 A B C D E F G H A B C D E F G H 0101 A2 0125 B5 020

42、5 A12 0206 G7 0207 A11 0208 A10 USA Reserved CU15D3 Reserved ReservedReserved Reserved Jumper 47u 3122 9122 5120 5121 2121100u220u CU15D3 UF1922P 123456789101112 12 F108 2R7 Reserved Jumper *: Reserved Item Number should be YK type BZX84-C24 68u EuroWW 0101UnpolarizedUnpolarized Polarized F102 HEATS

43、INK 0125 3127 1R -8Vr 1K5 3150 470R 3124 F101 HCS0528 0101 1 2 3141 10K +12V 0208 F105 10K 3110 3202 3K3 100n 2161 3119 F112 F224 2n2 2131 1K2 3222 F216 F213 68R 3225 10R 3142 7253 BC327-25 F223 F203 12 43 F214 F218 UF1922P4 5120 Vfb 8 Vref 2232 UC3842A 7110 1 COMP 5 GND 3 Isense 6 OUTPUT 4 RtCt 7 V

44、CC 2 F121 5130 +5Vr 6101 BZX79-C15 BZX79-C15 6100 3201 10R 2240 220u 3K3 3235 3109 1K 390R 3223 BYD33D 6220 4u7 2129 0260 HEATSINK +12Vr 100u 2133 2142 100n 2260 10n F125 3112 22R 22u 2234 +12V 3207 1K 680K 3117 BYD33D 2242 100u 6240 3206 3K3 F204 1n8 2102 +5V 2221 47n F122 3106 1K 100u 2134 VDC2 10

45、0n 2150 2126 2n2 7141 BC857B 7260 2 GND 1 IN 3 OUT 3128 1R5 3151 56K 470R 3208 VFTD VFTD SB360 6210 UDZ-20B 6141 3113 270R 2231 2120 220n +12V 33n 2128 5210 6u8 2u2 5230 2322593 3120 6230 BYW98-200 2213 VDC2 5226 4u7 UDZ-22B 6201 VDC1 330p 2109 F230 1N4006 6107 470p 2127 6250 BYD33J F106 2 3 4 5 6 F

46、104 F209 EH-B 0207 1 F215 F202 F210 2230 1m +5Vr 7201 TL431CLP 2 1 3 1n 2104 2210 2m2 F103 3123 18K +5V 1SS355 6130 7125 STP3NB60FP 6150 UDZ-4.7B 3111 68R 2201 100n 3104 15K 2253 F221 2202 22n F205 3103 33R 3203 100R 7131 CQY80NG 2130 2252 10u F206 F219 2250 100u 7150 BC847B -8V BC857B 7252 5125 83R

47、 3236 3230 1K 2119 5220 10u 100u 2222 UDZ-2.7B 6202 11 13 14 15 16 17 18 2 5 7 9 F212 5131 CT283D3 10 F110 +12Vr -8Vr F211 12K 3232 +5V 3122 2R7 10K 2121 100u F111 3129 3221 1K2 F222 5K6 3229 4n7 2106 18K 3134 7254 BC847B VDC1 -8V +5V 2243 7249 L7908 GND 1 IN 2 OUT 3 3125 10K 5250 10u 6133 1SS355 -8

48、V T2.0A H 250V 1120 5240 10u 3126 1R 9122 F208 3205 220R 3102 22K 3220 3 4 5225 4u7 68R 3224 F107 5121 CU15D3 1 2 3105 15K F220 1 2 2111 100n F100 0206 EH-B 10K BYD33D 6132 2n2 2125 3204 3K3 3234 F217 F201 S1NB80 6102 43 1 2 470R 5255 1u F207 3233 6106 1N4006 2u2 2141 T 2220 330u BC337-40 7251 F109

49、1 10 11 2 3 4 5 6 7 8 9 6129 0205 EH-B POWER SUPPLY UNIT CDR3-ECO CL 06532151_013.eps 241100 Block diagrams, Circuit diagrams and PWBsGB 37CDR7795. Layout PSU CDR3-ECO POWER SUPPLY UNIT CDR3-ECO - TOP VIEW POWER SUPPLY UNIT CDR3-ECO - BOTTOM VIEW CL 06532151_014.eps 241100 Spare parts listGB 77CDR77910. Headphone board ? 21004822 126 14585 100nF 10% 50V 21014822 124 81151 22F 50V 21024822 126 14585 100nF 10% 50V 21034822 124 81151 22F 50V 21045322 126 10511 1nF 5% 50V 21055322 126 10511 1nF 5% 50V ? 31005322 117 11726 10 5% 31015322 11