PHILIPS DVD763A
Manual de Servicio

EN 68

9.

DVD763SA

Circuit Descriptions and List of Abbreviations 9.3 Loader/Mono Board
Loader

K R
DVDalas2+ Loader-interface

2.5V A
CL 96532065_071.eps 130799

HF Buffer

Iguana (front-end processor)

Program Memory

Figure 9-2 TL431
I2S S2B

This reference component has two functions: � A very stable and accurate reference diode � A high gain amplifier. When the output voltage increases (due to a reduction in the load), the voltage across RSENSE-2 (R3290/R3291) increases to above the internal reference voltage of 2.5V. The TL431 will conduct and the current through the opto-coupler will increase. This results in an increase of the voltage at pin 4 of IC1, which will reduce the 'on' time of Q1 (FET 7125). In the event of an output voltage decrease (due to an increase in the load), the control circuit will operate in the opposite way. Primary Current Sensing The current through FET Q1 will result in a voltage drop across RSENSE-1 (R3120-23). This line goes to pin 11 of IC7130, which is the current sense input. The higher the input voltage, the more the primary current is limited. In this way, the maximum output power of the power supply is limited. Under-voltage Protection If the supply voltage at pin 13 of IC7130 drops below 7.2V (typical), e.g. due to a shorted secondary voltage or excessive load, the drive pulse at pin 12 is disabled and the controller will switch 'off'. Over-voltage Protection An internal over-voltage protection circuitry continuously monitors the Vcc pin. If, after start-up, this voltage exceeds 40V, the internal latch circuit is triggered, the output buffer is disabled, and the SMPS goes into over-voltage protection. Now a complete restart sequence is required. Note: If the event of the over-voltage situation remains present, the SMPS will go in sequence of protection, start-up, protection and the cycle repeats. This effect is highly audible.

HF STi55XX (back-end processor) PCM FURORE 2 Audio

SMI (SDRAM) EMI (FLASH)

Video

Others

BACK-END FRONT-END

Module Interface
CL 26532053_022.eps 260402

Figure 9-3 Block Diagram Loader/Mono board The SD4.00_SA_CH (SACHI_4) is the 2nd generation Philips Architectural Standard Design of SACD mono board based on Furore 2, and will be used in the new generation of SACD players. It is designed in a multi-task way so that it can support the following optional main functions: � SD4.00_SA_CH: Support SACD player with 5-disc changer. � SD4.00_SA: Support SACD player with single-disc. � SD4.00_CH: Support DVD player with 5-disc changer but without SACD playback. � SD4.00_SA_I2C: Support SACD player with single-disc and I2C slave. The SD4.00_SA_CH (SACHI_4) module consist of the following key components: 1. OPU: Mercury 2 Loader VAL6011/14 (slim type) for a single-disc SACD player, or DVD VAM6001/14 mechanism for a 5-disc SACD changer. 2. Front-end: M2 Basic Engine. 3. Back-end: DVD Host Processor STi55xx and Furore 2 SACD DSD/DST decoder. 4. Power supply: To convert the PSU voltages to the correct values. 5. Reset circuit: This circuit that the booting of the several devices on the mono board takes place in the correct order. 9.3.1 The Optical Pick-up Unit (OPU) The Mercury 2 Loader has an optical unit consisting of two lasers: � One for CD with a wavelength of 780 nm. � One for DVD with a wavelength of 650 nm. The TZA1033 (item 7105) controls the data from these lasers, and the supply to them. 9.3.2 Front-end: the Servo Part The front-end consists of: � The Loader interface � The Servo Processor/Decoder