Philips DVDR1000/001 Service Manual page 160

GB 160 9. DVDR1000 /0x1 /691
9.2.3 IR Receiver and Signal Evaluation
The IR receiver [7140] contains a selectively controlled
amplifier as well as a photo-diode. The photo-diode changes
the received transmission (approx. 940nm) in electrical
pulses, which are then amplified and demodulated. On the
output of the IR receiver [7140], a pulse sequence with TTL-
level, which corresponds to the envelope curve of the
received IR remote control command, can be measured. This
pulse sequence is input into the controller for further signal
evaluation via input IRR [7156, pin 2].
9.2.4 Motor Driver Flap
The flap-motor is controlled via the 2 Port-Pins (MD1, MD2)
of the P (7156, Pin 12, Pin 100). The motor driver part is
constructed as a bridged dual power operational amplifier.
Between the IC outputs (7120, Pin1, Pin3) and a Boucherot
circuit (2121, 3126) suppresses a spurious 3MHz oscillation
from the output stage. The two ports-pins (MD1, MD2) of the
P are PWM-outputs and are controlled in the following way:
Flap Motor:
MD1
off H
open H
close L
Duty Cycle 50% for OPEN and CLOSE
Duty Cycle app. 10% for CLOSE
Duty Cycle app. 10% for OPEN
Figure 9-3
For the detection of the end-positions of the flap there are two
switches (1178, 1179) installed and the information is
evaluated from the P via the signals SW_1178 and
SW_1179.
Flap Switches:
SW1
open L
closed H
moving H
error L
Circuit-, IC Descriptions and List of Abbreviations
MD2
L
PWM(H)
PWM(L)
CL 16532095_112.eps
150801
SW2
H
L
H
L
9.2.5 Bi-Color LED (Standby and ON)
The STBY-LED is a red/green bi-color-LED and is controlled
via the STBYLED-signal of the P (7156 Pin 10) in the
following way:
Colour of STBY LED Status of the Set
red
green
9.3 Analogue Board Europe
9.3.1 Microprocessor TMP93C071F
The microcontroller „AIO" TMP93C071F is a 16bit
microcontroller with internal ROM and 8kB RAM. It includes
the following functions:
• A/D converters
• composite sync input
2
• I C bus interface
Following connection to the mains, a positive pulse on the
reset input on the P is generated by the reset-IC TL7705
(Pos.7900). The system clock is generated with the 20MHz
quartz (Pos. 1994).
9.3.2 Bus Systems
The communication between the P and the other functional
2
groups is via the I C-bus (SDA, SCL). The clock rate is
approx. 95kHz.
Functional groups on the I
2
• E PROM ST24E16 (Pos. 7815)
• Tuner (Pos. 1705)
• Matrix-switch STV6410 (Pos. 7507)
• Audio IC / MSP (Pos. 7600)
• Display board (Pos. 1987)
• VPS-IC (Pos. 7990).
2
9.3.3 E PROM
2
The E PROM ST24E16 (Pos. 7815) is an electric erasable
and programmable, non-volatile memory. The E
stores data specific to the device, such as the AFC-reference
value, clock-correction-factor, etc. The data is accessed by
2
the P via the I C-bus.
9.3.4 VPS, PDC, Teletext (Europe Only)
The STV5348 (Pos. 7990) is a VPS, PDC, and Teletext
Decoder with an external 13,875Mhz quartz.
The following data formats are identified:
• VPS (Timer data and station name)
• PDC Format 2 (Timer data and station name)
• PDC Format 1 (station name and time)
• TXT header line (time for „time download")
9.3.5 FOME
The FOME-circuit compares the video signal coming from
the tuner and the one coming from the Scart-plug 1. If the
video-signals are identical the output of the FOME-circuit is
low.
9.3.6 Fan Control
The fan control circuit is necessary to control the speed of the
cabinet fan (Pos. 1984) according to the requirements in
temperature and noise. The temperature is measured via an
NTC on the display board (Pos. 3145). When the
temperature is lower than 25°C the fan-voltage is approx. 5V
STBY
ON
2
C bus:
2
PROM