Circuit- And Ic Description; Front Board; Analog Board - Philips DVDR3355 Service Manual

8.

Circuit- and IC description

8.1. Front Board (Panel – Display + Key)
8.1.1. General
This board consists of the following parts:
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Slave μP
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Frontend (Audio & Video)
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VFD Heater voltage Generator
8.1.2. Slave μP (IC 7105: UPD16316GB)
The core element of the Front Display + Keyboard is the slave
μP. It runs on a 5V supply and is responsible for the following
functions:
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Interface with the Domino chip on the Digital Board
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Evaluation of the keyboard matrix within Front board
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Decoding the remote control commands from the infra-red
receiver
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Activation and control of the display
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Timer Wake-up activation
It runs on two clock frequencies namely:
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5MHz for normal operation
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32.768KHz for the real time clock
8.1.3. Interface to the Domino chip
It communicates with the Domino Host on the Digital board
via a 6-wire synchronous serial interface. The Host is always
the master to generate the communication clock to the slave
μP irrespective of the direction of data transfer.
8.1.4. Evaluation of the keyboard matrix
A key matrix is used on the Front board. The slave μP does
the key scanning with FIP9 - FIP24 (pin 23-26 and 29-40) as
output and KEY_A - KEY_C (pin 41-43) as input. Each key is
assigned a key code based on the output and input ports, and
the slave μP will do the evaluation by getting the key codes.
8.1.5. IR receiver and signal evaluation
The IR receiver on the Front Board contains a selectively
controlled amplifi er as well as a photodiode. The photo-diode
changes the received infrared transmission to electrical
pulses, which are then amplifi ed and demodulated. On the
output of the IR receiver, a pulse sequence with TTL-level,
which corresponds to the envelope curve of the received
IF remote control command can be measured. This pulse
sequence is fed into the slave μP for further processing via
pin 13.
8.1.6. Vacuum Fluorescent Display [1203: HUV-08SS65T]
The VFD is fully controlled and driven by the slave μP.
8.1.7. VFD Heater Voltage Generator
The oscillator circuit provided by [5100, 2101, 2102 & 7100]
provides the necessary sine wave signal transistors [7101,
7102 & 7103] to generate the 50% duty-cycle 48KHz AC
square-wave signal for the fi lament of the VFD.
8.1.8. Timer Wake-up activation
During the Standby mode, the slave μP provides a wakeup
service (POWER_CTL-line switches to high) to Domino Host
on the Digital Board. It will then starts up and asks for the
wake-up reason.
Circuit- and IC description
8.2.

Analog Board

8.2.1. General
The pcba consist of the following parts:
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8.2.2. Fan Control (OPTION)
To avoid unwanted temperatures inside the set (especially
the Laser on the OPU of the drive is very sensitive) a fan is
located at the rear of the Basic Engine. The fan is ON when
the set is in ACTIVE Mode, and OFF when the tray opens.
When the set is in STBY Mode, the fan is switched off.
8.2.3. Power Supply Unit
This power supply functions on a circuitry combination
of a SMPS control IC [7400], switching FET [7401] and
transformer [5400] as a switched-mode power supply
(SMPS).
Feedback control is provided by the IC 7404, which compares
the 5V-output voltage via voltage dividers [3421, 3422 &
3423] with an internal 2.5V reference voltage. The output
voltage is fed to an optocoupler [7403] that provide the
insulation between the primary and secondary parts as a
current value into pin 3 of the IC 7400.
The following are the various supply lines provided:
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Standby modes:
In Standby mode, STBY control line is low, switching off
3V3SW, 5V, 5N (provision), 5VE, 12V and 12VE supply
reducing the power consumption.
3139 785 30981
Fan Control (OPTION)
Power Supply Unit
Tuner Frontend
Audio ADC/DAC
3V3SW to CU, DAC_ADC, Digital Board
5V to IOA, IOV, CU, MSP, DIGIO and FV
5N to MSP (provision only) and Digital Board
(provision only)
5VE to Basic Engine
5V_BE to Digital Board
5NSTBY to IOA, IOV, DAC_ADC
5VSTBY to IOA, IOV, FV, MSP, DAC_ADC, Front
Board
8VSTBY to MSP
12V to Digital Board
12VSTBY to CU, IOV, DAC_ADC, Front Board
12VE to Basic Engine and Digital Board (provision
only)
33VSTBY to FV
VGNSTBY to Front Board, CU
8. EN 51