Pioneer cx 3212 service manual
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Extracted text from pioneer cx 3212 service manual (Ocr-read)
Page 1
CX-3212 2 1234 1234 C D F A B E 1. CIRCUIT DESCRIPTIONS 1. Front end section (MN2DS0016AAUB : IC1501) MN2DS0016AAUB is a 1 chip LSI for DVD-Player. A DVD-Player system can be constructed by connecting this LSI, driver IC, SDRAM, Flash-ROM, Audio-DAC, etc. This LSI includes a front end (SODC/FE) which executes RF signal processing, servo processing and decode processing, a back end (AV decoder/BE) which executes video decode processing such as MPEG1/MPEG2/JPEG and audio decode processing such as DVD-Audio/Dolby Digital /DTS/MP3, and a system controller which controls the system. The front end section realizes optical head signal computation processing and RF signal processing, digital signal processing (16-8 demodulation, error correction) for DVD-ROM playback according to the DVD specifications, digital signal processing of CD-DA/CD-ROM (error correction), AV decoder transfer, servo control, spindle motor control and seek control. In the case of MN2DS0016AAUB, the front end servo system waveforms, such as FE, TE and AS, are not observed as in the case of DVD mechanism module (MS4) CX-3183. Please pay attention. 1.1 Analog block (MN2DS0016AAUB : IC1501) The functions of the analog block are as described below. 1. Reference power circuit 2. SERVO system/DPD system signal processing circuit Gain switching amplifier and Low Pass Filter (LPF) 3. RF signal processing circuit RF adding circuit, circuit to make inline, Variable Gain Amplifier (VGA) circuit 4. Laser power control (LPC) circuit 5. A/D converter for SERVO (10 bit, DPD system-4ch), PWM 1.1.1 APC circuit The optical output of the laser diode (LD) has a large negative temperature characteristic. Therefore, if the LD is driven by a constant current, a constant optical output cannot be obtained. APC circuit is a circuit to control the current so that the output at the monitor diode (MD) will be constant. MN2DS0016AAUB includes 2 types of APC circuit, one for DVD and the other for CD. The LD current can be obtained by dividing the measured voltage between DVDLD1 (CDLD1) and 5 V by 6 Ω (1.5 Ω x 4=6 Ω), in the case of DVD (CD). It will be approximately 50 mA (45 mA) in the case of DVD (CD). The potential difference between DVDLD1(CDLD1) and 5 V is set to approx. 300 mV(270 mV). DVN Chip (MN2DS0016AAUB : IC1501) CDMPD14 DVDMPD PU UNIT 2
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CX-3212 3 5 678 567 8 C D F A B E 1.1.2 FE forming circuit Focus error (FE) forming circuit The signal from PU, FE1 and FE2, are AD converted inside IC1501 and captured. After that, a differential is obtained by taking the offset cancellation into consideration, and FE is obtained. FE = (FE1) - (FE2) 12 11 FE2 FE1 CN1101 136 137 VIN5 VIN6Input AMP Gain switching -6 dB, 0 dB, 9.5 dBLPF 50 k/100 kHzLPFBuffer LPF 50 k/100 kHzG=0 dBBuffer AMP Selector Selector Gain switching 3 dB, 9 dB DVN Chip ADC driving AMP Gain switching 6/7.5/9/10.5/ 12/13.5/15/ 16.5/17/19.5 dBADC ADC After 10 bit ADC FE signal forming circuit 1+Pfbal0,1/0x0100 1-Pfbal0,1/0x0100 Offset cancelFbal coarse adjustment value FE AMP DVN Chip FE1 FE2+ -