Philips DVDR1000/001 Service Manual page 55

5.5 Loop Tests
The following loops can be distinguished:
• Loops performed on the digital board only
• User Dealer loops performed on the digital and analogue
board
• System loops performed via an external connection:
outputs are looped back to the inputs.
5.5.1 Nucleus 900: Digital Audio Loop
This nucleus tests the audio path through the digital board
NUCLEUS 900: AUDIO LOOP DIGITAL
ANALOGUE BOARD
DIGITAL BOARD
7552
VIP_ICLK: 27MHz
VIP
AUDIO ENCODER
GND
Figure 5-9
Diagnostic Software and Faultfinding Trees
7202
STI 5505
7703
7100
VSM
7410
EMPIRE
CL 16532095_075.eps
DVDR1000 /0x1 /691
5.5.2 Nucleus 901: Audio User Dealer Loop
A PCM audio sine of 12kHz is generated in the Sti5505 for a
while and sent to the analogue board. The signal coming
from the analogue board is encoded again and sent to the
memory of the host decoder for comparison. This nucleus
tests the components on the audio signal path:
• Host decoder Sti5505
• Flex connection between connector 1602 (digital board)
and connector 1900 (analogue board)
• DAC
• Op-amp
• Scart switch STV6410
• ADC
• Audio Encoder
• VIP
• VSM
ANALOGUE BOARD
DIGITAL BOARD
VIP
150801
5.
NUCLEUS 901: AUDIO USER DEALER LOOP
7507
STV6410
7002
7004
ADC
connector
1900
connector
1602
I2S
7552
7703
AUDIO ENCODER
7410
EMPIRE
Figure 5-10
GB 55
7100
DAC
connector
1900
connector
1602
I2S
7202
STI 5505
7100
VSM
CL 16532095_076.eps
150801