Philips-MCM-8-Service-Manual(1) 电路图 维修手册.pdf

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1、CLASS 1 LASER PRODUCT Service Manual MCM8/21/22/25/30/37 TABLE OF CONTENTS Page Location of pc boards fr Reparaturen sind Original-Ersatzteile zu verwenden. Sicherheitsbauteile sind durch das Symbol ! markiert. I Le norme di sicurezza esigono che lapparecchio venga rimesso nelle condizioni originali

2、 e che siano utilizzati i pezzi di ricambio identici a quelli specificati. Componenty di sicurezza sono marcati con ! GB After servicing and before returning set to customer perform a leakage current measurement test from all exposed metal parts to earth ground to assure no shock hazard exist. The l

3、eakage current must not exceed 0.5mA. DISMANTLING INSTRUCTIONS Dismantling of the Cover Cassette and Universal Loader 1) Remove the Cover Cassette (pos 150) in the direction as shown in Figure 1. 2) Loosen 4 screws to remove the Cover Top (pos 240) by sliding it out towards the rear before lifting u

4、p. - 2 screws on the rear - 1 screw each on the left it is a dual-frequency oscillator with ceramic resonators 5300 and 5302, which resonate at 500kHz and 425kHz respectively.The resonators are switched by transistors 7309 and 7316, controlled by the OZ_SW line from the port expander 7406. The reaso

5、n for 2 frequencies is to avoid tuner disturbances in the AM-band. The oscillator signal is shaped to square wave with 7312-2, afterwards buffered and fed to the amplifier modulators (ROZ to the right channel, LOZ to the left). One channel gets inverted clock to balance supply loading. Modulator The

6、 modulator forms the pulse width modulated signal. For each channel a seperate modulation is required. Power FETs The FETs require drivers which supply the gates. One for the high-side-FET and one for the low-side-FET. Because of the different supply voltages also an additional level shifter is nece

7、ssary per driver. Output filter The output filter is necessary to block the 500kHz square wave signal from the speaker. Refers to the left channel in schematic diagrams. It consists of a series-mode coil 5101 and a capacity of approx. 550nF (2116, 2134), which forms a Chebycheff filter with 40kHz cu

8、t-off frequency at 6 load. For EMC reasons both, the speaker output and the return ground are fed through a common mode coil (5102).The filter is further improved by splitting the output capacity into 2116 before and 2134 after the common mode coil. All above mentioned circuitries are located inside

9、 the metal shielding box. LF Analog Audio Signal Modulated Digital Audio Signal +VL -VL +VL 0 0 -VL t Duty cycle 9:1 (DC value nearly +VL) Amplitude pos. max. Duty cycle 1:1 (DC value is zero) Amplitude zero Duty cycle 1:9 (DC value nearly -VL) Amplitude neg. max. Class-D Circuit Description (BASED

10、ONPOWER2003 MODULE75-150W CLASSD) V1L+7,5V+AMPV1L+7,5V V1L -37V +5V -45V -37V -45V -AMP-45V OFF ON OFFON Analog Pre-amp. Modulator Driver Power-amp. Level shifter Level shifter Square wave Oscillator analog audio signal f= 20Hz .20kHz amplified analog audio signal f= 20Hz .20kHz square wave 500kHz d

11、uty cycle 1:1 square wave 500kHz variable duty cycle 0V 5V 0V 5V square wave 500kHz variable duty cycle -45V +52V square wave 500kHz variable duty cycle -45V +45V square wave 500kHz variable duty cycle -45V -39V output filter Blockdiagram Class D 2002 04 05 Blockdiagram Class D 11-211-2 Functional D

12、escription: Refers to the left channel in schematic diagrams. The first stage of the modulator is an error integrator which compares the input to the (24 dB amplified) output signal of the power stage.The difference is leading to a current, which loads the integrator 7122-A.The second stage (7122-B)

13、 adds the 500kHz rectangular oscillator signal, creates high gain and low distortion and is again integrating.The output signal leads to a triangle wave form (see oscillogram E).The DC value of this triangle signal is floating, dependent on the amplitude of the analog input signal.The next stage is

14、a comparator, which compares the integrated voltage with the internal switching levels - thus creating a voltage controlled duty cycle. 7122 C and D improve the shape of the pulses. For details see oscillograms A-F. At pin 8 of IC7122 there is a square wave with the same frequency and duty cycle as

15、the desired output. The next task is to feed this information to the output FETs. Both FETs are n-channel types, so they are modulated by feeding the gate in respect to the source connection. Inverters 74LV14 are used as drivers.The driver for the low- side FET (7121) is supplied by the negative sup

16、ply -VL2 and a voltage +VL (generated by 7115 and 6113), which is 7.5V higher than -VL2.The digital signal is level-shifted by 7128 to the low side driver stage. 3142, 6111 and 2126 together form a delay circuit for rising edges by approx. 100ns for the low side FET. 3154, 6109 and 2137 delay the ri

17、sing edge by 50ns for the high side FET.This to compensate the switch-off delay of the FETs and ensures that both FETs are not conducting at the same time. The high-side FET (7109) is controlled by the inverted signal taken from pin 2 of 7118, which is level-shifted by transistor 7119.The driver for

18、 the high-side FET is supplied by a floating voltage between the amplifier output -V1L and +V1L, created by the charge pump 6110, 2114 regulated by 7114 and 6114 to a 7.5V higher level.The pump is additionally supplied (via 3151) by +45V to ensure supply at start-up (no signal).The last stage in the

19、 gate driver consists of three gates in parallel for increased output current for the capacitive load of the FET. For additional increase of the switching speed push/pull transistors 7132/7111 are added. Protection Circuits: The amplifier is protected against low load impedance (including short circ

20、uit). Current is sensed by shunts 3101, 3130 in both supplies. Overcurrent at the positive supply is then sensed by 7104, the negative supply overcurrent triggers 7117, which then also triggers 7104.The collector current in turn triggers the monoflop 7122-5 and -6, giving a High pulse at pin 10.This

21、 shuts off level-shifter 7128 and blocks transistor 7129 and 7131, which draws current into the emitter resistor 3134 of level-shifter 7119. It is now also shut off. So, both FETs are shut off within approx. 0,2 sec. The monoflop can be reset by: - switching mains off and on again - pressing Standby

22、 button and afterwards any source button - plugging headphone in for a short moment When a headphone is used the amplifier is shut off.This is done by pulling pin 13 of 7122 via signal line AMP_OFF and transistor 7130 to high level.The line AMP_OFF is controlled by the port expander 7406 which detec

23、ts the headphone via signal line HP_DET. The loudspeakers are protected against DC voltages resulting e.g. from defective FETs.Voltages higher than 2V are detected by 7110 respectively 7112.The transistors conduct and pull the DC_PROT line down, blocking transistor 7243 which in turn disables speake

24、r relay 1201. Adjustments: The gain of the class-D amplifier is 24dB, adjusted by the feedback resistors 3155, 3136, 3149 and the input resistors 3139, 3340.The input reference voltage for 7122-A is approx. half the supply, therefore 3144, 3148 are used for offset compensation.This compensation has

25、to be fine- tuned with trimpotentiometers 3306 and 3307 to obtain 1mV DC output. Service Hints: The analog part of the Combi Board can be repaired without opening the metal shielding box. In case of a Class D problem it is advised to disassemble the board first, desolder the metal bottom cover of th

26、e shielding box and assemble the board again.This takes a few minutes only. To de-solder the metal bottom cover proceed as follows: 1)Remove top cover of shielding box to reduce heat flow 2)Do not use de-solder wick 3)Simply hold the board upright down as shown in picture 1. Heat up solder joints an

27、d move tip of soldering iron slowly along the edge of the metal frame. Solder will flow along the soldering tip and rest on the metal plate. A small amount will drop off. A small gap will become visible as indication that the solder connection is released. When all solder joints are released the cov

28、er can be removed by help of a screwdriver. Begin at the corner indicated by an arrow see picture 2. To re-mount the metal bottom cover proceed as follows: 1)The solder connections are not distributed evenly. Therefore the cover has to be mounted in that way that the arrow indicator on the cover is

29、positioned in line with the arrow printed on the printed board see picture 3. put a screwdriver underneath the plate and lift it desolder 2 solder will rest on the metal plate desolder 1 Class-D Circuit Description (BASED ONPOWER2003 MODULE75-150W CLASSD) 2)Press the metal cover smoothly down until

30、the gap between cover and printed board becomes a minimum. This is important for proper shielding. 3)Heat up the residual solder on the metal cover.The solder will flow back to the solder areas. If necessary apply additional new solder. 4)Take care that all solder joints are re-soldered again. Atten

31、tion: Poor soldering of the metal shielding box results in disturbance of the tuner. In most cases the FETs 7109 and/or 7121 for the left channel, respectively 7218 and/or 7231 for the right channel will be defective.This can easily be checked with an ordinary Ohm-meter. LEFTCHANNEL: In case 7109 is

32、 defect replace following parts: 7109, 7111, 7132, 7105, 7119, 7104, 3101, 3103 and 2106 In case 7121 is defect replace following parts: 7121, 7113, 7133, 7118, 7117, 3129, 3130 and 2118 RIGHTCHANNEL: In case 7218 is defect replace following parts: 7218, 7221, 7244, 7209, 7228, 7208, 3205, 3209 and

33、2206 In case 7231 is defect replace following parts: 7231, 7210, 7245, 7235, 7227, 3241, 3243 and 2220 Attention: Do not forget to adjust the DC-offset after replacing the FET! If none of the FETs is defective the fault is most probably located in the modulator.To check the operation - follow the gi

34、ven signals. General description of Oscilloscope setup: The following signals are measured on condition: AUX in = 500mV/1kHz, Volume = -28dB Load = 2 x 6 Measuring point Acan be found on circuit diagram 3. All other measuring points are shown on circiut diagram 4 respectively 5. Measuring point A: O

35、utput pre-amplifier Normal analog signal measured (1kHz- Timebase 1s). If this signal cant be measured - the fault is outside the shielding box. Measuring point B: Input Modulator The 1kHz signal is not visible anymore. Reducing the timebase to 1s shows the oscillogram below. Y-Deflection CH1 = 20V/

36、DIV Ground Ch1 & Ch2 Y-Deflection CH2 = 20V/DIV Timebase = 1s Triggerlevel =-33,6V Triggered on Ch1 press metal cover down until gap is a minimum align arrows gap Service Hints pict. 1 pict. 2 pict. 3 11-311-3 Measuring point C: The first stage of the modulator is an integrator. An integrated rectan

37、gle results in a triangle. Measuring point D: The oscillator signal (squarewave) is fed to the second integrator (7122-B). Measuring point E: The integrated rectangle results in a triangle. 7122-C works as a comparator. 7122-D improves the shape of the pulses. Measuring point F: Output modulator In

38、this pulse width modulated square wave the analog Audio signal is included. Measurements with an analog scope will show a jitter on the falling edge. The modulator frequency is still fixed to 500kHz. Similar to a frequency modulation - in this case the amplitude of the analog audio signal varies the

39、 pulse width, the frequency defines the speed. Measuring point G: The low-side driver signal (Ch2) is the modulator output level-shifted by transistor 7128.The high-side driver signal (Ch1) is the inverted low-side driver signal level-shifted by transistor 7119. Service Hints Measuring point H: gate

40、-signal of the FETs Ch1 = H1, CH2 = H2 Measuring point I: Digital output signal. Measuring point J: The following three signals are measured after output filter 5101 with different timebases. Measuring point K: After common mode coil 5102 - the audio signal is restored. Service Hints 11-411-4 SOURCE

41、 SELECTOR PARTOSCILLATOR & PRE-AMPLIFIER PARTAMPLIFIER PART LEFT CHANNEL AMPLIFIER PART RIGHT CHANNEL AUDIO FREQUENCY & LOGIC PART Inputs: AUX Tape / USB / Sound Agent Tuner CD Source Selector IC + sound processing Data generation for spectrum analyzer Digital Out (provisional only) Overvoltage prot

42、ection for: +AMP -AMP +5V6 +12V_A Control Lines Generation of following supplies: +12V_A, +12V_M +5V6 +5V_AMP Pre-Amplifier + mute circuit Adjustment of offset 500kHz Square wave Oscillator Headphone Amplifier Subwoofer out (provisional only) Port Expander (shift register) Generation of +5V_CD Fan c

43、ontrol Modulator Driver + Level shifter Power FETs Protection circuits Modulator Driver + Level shifter Power FETs Protection circuits Speaker relay p Chapter 11-5 Signal flow Chapter 11-7 Chapter 11-8 Chapter 11-9 Chapter 11-6 Power 2003 75 - 150W Class D Combi Board Circuit Diagram Overview P2003

44、Class D Drawing Overview 2003 11 18 12 3 4 5 11-511-5 1 1 1 1 VOLUME I RIGHT SUR. SOURCE SUPPLY POWER SELECTOR TREBLE LEFT VOLUME II LOGIC LEFT REC IIC BUS BASS ALC BASS LEFT VOLUME I LEFT SUR. TREBLE RIGHT VOLUME II RIGHT BASS RIGHT 1 1 Pos 3501,3502 1R0 1010 B15 AMP+ AMP+ AMP- 75 Watt only N.C. 1K

45、 for 12367 SILD/uP CLK GND_D SICL/PORE/uP DATA -VKK 5V6 ECO LOW_PWR_CTRL 5678 SICL/PORE/uP DATA 5K6 for 1112 F1 SILD/uP_CLK B C D E F G H 1002 A15 1005-1 A1 1005-2 A1 1006 A15 Only for digital out GND not used GND_A GND_D 45 I2C_CLK NTC 89101112131415 1234 75 Watt only NTC GND_D F2 910 1028-B A8 250

46、0 A3 131415 A B C D E F G H A +5V_CD OUT +5V6_CON(ECO) GND 2537 C3 2538 B12 2539 B11 2540 C3 GND_D CD_RIGHT 2543 D8 2546 D8 SICL/RAB/uC RESET CD_LEFT 1011 C15 1012 G15 1013 D1 1015 F1 1018 F1 1020 D1 1022 B1 1026 E15 1027 G1 1028-A B1 LINE OUT TU_DATA TU_CLK FROM/TO FRONT TU_ENAB/MPX F1 PWR_DWN 2562

47、 G5 2563 G5 2501 A8 2519 B1 2520 A2 2526 A13 2527 A14 2528 A3 2529 A12 2531 A2 2532 A13 2533 B13 2534 B3 2535 B3 only DIGITAL COAX 2536 B10 +10V/+12V/+A +3V/COAX1 LOW_PWR_CTRL 2541 D6 2542 D7 2578 H7 2579 H10 2547 D10 2550 D8 2551 D9 2552 E9 2553 E3 2554 D10 2555 E6 2556 E3 2557 F3 2558 F11 2559 F3

48、2560 G4 SPDIF for LINE OUT only for tape deck LINE OUT 2593 H9 3500 A2 3501 C3 TU_ENAB 2561 G5 3506 E12 3507 E12 2564 G5 2565 G5 2566 G6 2567 G6 2568 G13 2569 H8 2570 G10 2571 G11 2572 H9 2574 H9 2576 H8 2577 H8 +SPDIF GND GND_A 3523 B2 3524 A10 3525 B3 3526 B10 TU_STEREO CLIP 3529 B9 3530 B13 2581

49、D13 2582 D13 2583 G8 2584 D8 2585 F6 2586 A5 2587 A7 2588 A7 2589 A6 2590 B6 2591 A7 2592 A7 5DTC RAB/SICL/uC RESET GND_D -Vkk 3502 C3 3504 A2 3508 F2 3509 F2 3510 F3 3511 F3 3514 A3 3515 A13 3517 A14 3518 A2 3519 A2 3520 A3 3521 A11 3522 B2 for TAPE DECK or SPDIF GND TU_LEFT Pos 3525,2527 27K SA R,TP_REC_RIGHT TU_RIGHT +11V_A 3527 B3 3528 B11 3563 G6 3564 G6 3531 B9 3532 B10 3533 C2 3534 C5 3535 C8 3536 C8 3539 D9 3542 D7 3543 D9 3544 D10 3545 D3 3549 E6 MICROPHONE CD_SH_CLK/Tray IRQ for TAPE DECK only POWER_DOWN OVER VOLTAGE PROTECTION CIRCUIT -CMOS 3578 H9 3579 H10 358