Arcam-DivaDT81-tun-sm维修电路原理图.pdf
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1、DT81 DiVA DT81 Digital Radio Tuner Service Manual ARCAMARCAM Issue 1.0 RadioFans.CN 收音机爱 好者资料库 Contents List ! Contents list ! Circuit description ! Service guide ! Circuit diagrams ! Component overlays ! Circuit board parts list ! General assembly parts list RadioFans.CN 收音机爱 好者资料库 DT81 Circuit Des
2、cription Summary The L918 forms the basis of the DT81 DAB tuner. All the circuitry of the tuner is on the same board, with the exception of the front panel PCB. The tuner is based on the Roke Manor gold card which provides the RF receiver and DAB decoding. To accompany this module the DAB motherboar
3、d has various power supplies, a Hitachi H8 microcontroller, a D-A converter with output buffer, and an SPDIF transmitter. Power supplies and muting The mains transformer T1 is used for 230V and 115V operation, the voltage selection is done by fitting different fuses. F1 160mA is fitted for 230V and
4、F2 250mA for 115V. The front panel board is powered from the 7.5V unregulated supply (it has its own regulator). The digital supplies are switched by SW3, while the analogue supplies are on all the time while the mains is connected. Regulated supplies P15V, N15V. +/-15V for the output buffer and DAC
5、 5V regulator. P5VDAC. +5V supply for DAC. P5VDAB. 5V supply for DAB module. P5V. +5V supply for digital circuits - Micro and SPDIF transmitter. P10V. +10V supply for DAB module. P7V5_UR. Unregulated 7.5V supply goes to front panel. Z9 is a Toshiba TA7317. This controls the muting/bypass relay. The
6、same relay is used for power on/off muting and also FM tuner bypass mode. The muting circuit has a time constant of 2.5 seconds, so there is always a 2.5 second delay when un-muting the output. The FM tuner bypass switch is shown on this sheet (SW2) and is accessed from the front of the unit. Micro,
7、 DAB module, SPDIF Z204 is a Hitachi H8/3048F 16 bit microcontroller. It has FLASH program memory, and is programmed via header SK1. Z202 is a 64kbit parallel EEPROM used for storing multiplex data. this is where the system stores data about the multiplexes it finds when it does a search, and other
8、information (presets, compression level, sort type, display mode). Z205 is a 3 pin reset generator IC. SW1 is a latching push switch accessed from the rear of the unit. If the switch is pushed in, RDI_ON will be low. This has the effect of removing data services from the list of services. If the swi
9、tch is left out, RDI_ON will be high and the data services can be seen. SK3 is used to connect to the front panel, communication is done via the I2C bus. Power for the front panel comes in the form of P7V5_UR. Note that although P5V connects to the front panel, it is not used for power. Its purpose
10、is to light the front panel LED green. DAB module: JP1 is a 50 way SAMTEC connector which provides the interface to the Roke DAB module. All the I/O to the module is on this connector apart from the aerial input which has a cable going straight from the rear panel to the module. Communication betwee
11、n the micro and the DAB module is done via the serial port of each device on TX_DAB/RX_DAB. The digital audio output from the module comprise of MCLK (12.288MHz master clock), LRCK (48kHz left/right clock), SCLK (serial data clock) and SDATA (serial data). These signals go to the D-A converter, and
12、also to the SPDIF transmitter Z201. Z201 is the SPDIF transmitter. Each one of the differential ouputs is used separately. SPDIF_OP is for the optical output, SPDIF_CX is for the coax output. DAC Z101 is a CS4327 D-A converter, followed by filter/buffer Z102. This is followed by ac coupling capacito
13、rs. The relay RLY1 is the last stage before the phono output connectors. 2 stereo outputs are provided on SK101. SK102 is an input which gets routed through the relay when the relay is off. An external FM tuner can be connected to this, in order to avoid taking up an extra input on the amplifier. Wh
14、en the tuner is off or in bypass mode, the FM tuner is routed to the output. The digital audio outputs are also shown on this sheet. TX101 and associated components provide an isolated unbalanced SPDIF output on SK103, and Z4 produces an optical output. Software notes The system has non volatile sto
15、rage in the form of the EEPROM, Z202. The following information is stored there and is remembered at power up:- Service data - all the IDs and static prog types of the services available in the ensembles found in the last search. This is the information viewed when turning the knob. Service selected
16、 - last service selected. Display mode - prog type, dynamic label, data rate or signal quality. Display brightness - off, dim or bright. Compression level - off or 1-5. The following parameters are NOT remembered:- Engineering mode. If the unit is turned off while in engineering mode (or test mode),
17、 it will default back to user mode on power up. Bypass mode - the unit will always power up not in bypass mode. Secondary services - if a secondary service is selected when it is switched off, it will power up with the parent service selected. Erasing the EEPROM - to erase the EEPROM, go into engine
18、ering mode (SELECT +8), then hold down preset buttons 1,4,5,8. The display will say ERASING EEPROM followed by PASSED EEPROM TEST then EEPROM ERASED. If you switch the power off and on again, it will come on with all the parameters reset. Display mode - prog type Display brightness - bright Compress
19、ion - off. Selection Mode manual Test mode If you hold in the bypass button while powering up, this will put the unit in test mode. When the bypass button is released, the software version will be displayed. Pressing the front panel buttons will cause a message to be displayed. Turning the knob cloc
20、kwise or anticlockwise will cause a message to be displayed. Any RC5 remote commands will also be displayed, with command and system codes, and an asterisk for the toggle bit. Fault mode On switch on if the Roke module is not fitted, or if there is a problem with the RX or TX communication signal be
21、tween the module and the H8, the unit displays ERROR CIP FAILURE. DT81 Service Guide Fault diagnostics Fault Action No power Check mains fuse Check power supply rails No Audio output Check for digital output Check analogue power supply voltages Check DAC IC Fails to respond to commands Check supply
22、voltages Check DAB module No Display Check flex foil cable Check for dry joints on micro and display Spurious display readout Check for dry joints on display board Display reads “ERROR CIP FAILURE” DAB module not communicating with main micro replace DAB module Display reads “NO SERVICE FOUND” DAB m
23、odule not receiving signal check connections to DAB module/ replace DAB module Power supply test points Position Voltage TP1 0 volt reference TP2 +5 volts - DAB module TP3 +10 volts - DAB module TP4 +5 volts - DAC TP5 +15 volts TP6 -15 volts TP7 +5 volts Hints & tips ! No analogue signal - measure b
24、etween the junction of D10, D11 and D8, D9 for the secondary supply feed from the transformer, this should be 40 VAC. If this is low or missing the transformer will require replacing. ! Not responding to front panel controls check the processor is ok by pressing the bypass button, if the bypass rela
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