Pioneer cx 3268 service manual
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Extracted text from pioneer cx 3268 service manual (Ocr-read)
Page 1
CX-3268 2 1234 1234 C D F A B E 1. CIRCUIT DESCRIPTIONS DV5U Chip (MN2DS0018MAUB : IC1501) 2.2 2.2 2.2 2.2 14 24 25 103 104 105 106 2.2 2.2 2.2 2.2 CDMPD DVDMP 78 LD (CD) 65 LD (DVD) 15 MN2DS0018MAUB is 1-chip LSI for DVD-Player. The DVD-Player system can be\ constructed by connecting this LSI with driver IC, SDRAM, Flash-ROM, and Audio-DAC etc. This LSI has the front end part (SODC / FE) for carrying out RF signal\ processing / servo processing / decode processing, the AV decoder part (backend / BE) for carrying out video \ decode processing of MPEG1 / MPEG2 / JPEG etc. and audio decode processing of DVD-Audio / Dolby Dijital2 / DT\ S / MP3 etc., and the system controller for controlling the system built-in. The front end part realizes various processing such as optical head sign\ al arithmetic processing, RF signal processing, digital signal processing of DVD standard-compliant DVD-ROM play (16-8 \ demodulation, error correction), digital signal processing of CD-DA / CD-ROM (error correction), AV decoder tra\ nsfer, servo control, spindle motor control, and seeking control. With MN2DS0018MAUB, the waveform of servo system of front end such as FE\ , TE, AS cannot be seen in a same way as DVD mechanism module (LS1) CX-3250. Keep it in mind. 1.1 Analog block (MN2DS0018MAUB : IC1501) 1 Front end part (MN2DS0018MAUB : IC1501) The functions of analog block are as below: 1. Reference power supply circuit 2. SERVO system / DPD system signal processing circuit Gain switching amplifier and Low Pass Filter (LPF) 3. RF signal processing circuit RF adder circuit, in-lining circuit, Variable Gain Amplifier (VGA) cir\ cuit 4. Laser power control (LPC) circuit 5. A/D converter for SERVO (10bit), DPD system comparator, PWM 1.1.1 APC circuit The optical output of laser diode (LD) has a large negative temperatur\ e character. Consequently, if LD is driven at the rated current, a constant optical o\ utput cannot be obtained. APC circuit is the circuit for controlling the current so that the outpu\ t becomes constant for the monitor diode (MD). MN2DS0018MAUB has two types of APC circuit for DVD and CD built-in. In case of DVD (CD), the LD current can be obtained by dividing the vo\ ltage measurement value between DVDLD1 (CDLD1) and 5 V by 8.8 ohm (2.2 ohm x 4 = 8.8 ohm). In case o\ f DVD (CD), the LD current becomes approximately 45 mA (40 mA). The voltage difference between DV\ DLD1 (CDLD1) and 5 V will be 396 mV (352 mV). PU unit
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CX-32683 5 678 56 7 8 C D F A B E After 10bit ADC 12 11 FE2 FE1 CN1101 115 116 VIN7 VIN8 Selector LPF 50k Hz Input AMP Buffer LPF LPF 50k Hz G=0dB Buffer AMP ADC drive AMP Gain switching 6/7.5/9/10.5/ 12/13.5/15/ 16.5/18/19.5d ADC Selector ADC Gain switching 3dB, 9dB Gain switching -6dB, 0dB, 9 5dB DV5U Chip FE1 FE2 FE signal generation circuit + - 1+Pfbal0,1/0x0100 1-Pfbal0,1/0x0100 Offset cancel Fbal coarse adjustment value FE AMP DV5U Chip 1.1.2 FE generation circuit Focus error (FE) generation circuit The signals FE1 and FE2 from PU are AD-converted in IC1501 and imported.\ Then, the differential is taken by taking the offset cancel into account and it becomes FE. FE = (FE1) - (FE2)