Hitachi C28W40TN, Service Manual

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The Z02201 provides comprehensive and flexible tone generation and detection. This includes all tones required to establish a
circuit connection and to set-up and control a communication session. The tone generation furnishes the DTMF tones for PTSN auto
dialling, and the supervisory tones for call establishment.
The Z02201 communicates with the controller via a parallel interface, and also allows retrieval of modem/line status, control data
and programmable coefficients.
The controller Z02205 communicates to the MPEG processor via a 5V RS232 interface, using the Hayes AT command set.
The Z02205 controls the registers and memory of the data pump via a parallel interface, allowing DTMF dialling, circuit connection,
and data transfer.
The Z02205 controls the Off-hook line to the DAA, and checks the cadence of the Ringing detect pulses for a valid ringing signal
which is communicated to the MPEG processor.
The DTR and CTS signal lines on PL809 (provisions to and from the modem) are tied low with resistor links (R781, R782) to allow
the TTL level RS232 communication to operate between the modem and CPU without handshakes being needed.
TEST POINTS ON COFDM PCB
Test Point ID Net Name Function
A001 5v tuner filtered 5V supply to tuner
A002 9v tuner filtered 9V supply to tuner
A003 9v unfiltered 9V supply to tuner
A090 30v unfiltered 30V supply to tuner
A009 30v tuner filtered 30V supply to tuner
A235 30v 1st intermediate 30V current limiting point
A234 30v 2nd intermediate 30V current limiting point
A006 RF AGC in RF AGC line tuner front can
A004 IF 1 in / out IF1 IN/OUT loop through
A008 IF 2 out IF2 OUT front can
A011 IF2 in IF2 IN rear can
A013 ADD Tuner I2C address select
A018 RF AGC out RF AGC OUT rear can
A033 Tuner out-07 Tuner ADC data out bit 7
A032 Tuner out-05 Tuner ADC data out bit 5
A031 Tuner out-04 Tuner ADC data out bit 4
A030 Tuner out-03 Tuner ADC data out bit 3
A029 Tuner out-02 Tuner ADC data out bit 2
A028 Tuner out-01 Tuner ADC data out bit 1
A027 Tuner out-00 Tuner ADC data out bit 0
TP803 Clock out Unused 18 MHz clock out from tuner
A239 18MHz Clock-in 18 MHz clock to OFDM
A005 SDA-Tuner Tuner I2C data
A012 SCL-Tuner Tuner I2C clock
A238 SDA-Tuner-SW Ungated tuner I2C data
A237 SCL-Tuner-SW Ungated tuner I2C clock
TP801 /Clock-EN active low 18.288 MHz clock enable
A236 CONTROL 18.288 MHz clock enable
A026 18MHz-Clock
TP802 IC800 spare gate unused gate IC800
TP891 IC800 spare gate unused gate IC800
A231 10 Bit-ADC
A050 INT-ADC
A051 10 Bit-ADC
A047 10 Bit-ADC
A063 REF-TF
A080 REF-TF
TP804 STBYAD10
TP805 ENDA10
TP876 DRVss
A194 3v3-COFDM 3V3 COFDM supply line
TP877 EX-AD9 External ADC data bit 9/ tuner ADC data bit 7 link through
TP878 EX-AD8 External ADC data bit 8/ tuner ADC data bit 6 link through
TP879 EX-AD7 External ADC data bit 7/ tuner ADC data bit 5 link through
TP880 EX-AD6 External ADC data bit 6/ tuner ADC data bit 4 link through
TP881 EX-AD5 External ADC data bit 5/ tuner ADC data bit 3 link through
TP882 EX-AD4 External ADC data bit 4/ tuner ADC data bit 2 link through
TP883 EX-AD3 External ADC data bit 3/ tuner ADC data bit 1 link through