Arcam CD player 5.5-6 free download

File name 5.5+6 Alpha service manual.pdf

ARCAM ALPHA 5 CD PLAYER SERVICE MANUAL 1 ALPHA 5 CD SERVICE MANUAL ALPHA 5 CD PLAYER SERVICE MANUAL Issue 1 Serial No. 30000 Paul Newton/Andy Howe August '93 Arcam Drawing No. H04/0022 CONTENTS CIRCUIT DESCRIPTION Audio Board ... 2 Mono Board ... 2 Photo diode signal & Radial Error Processors ...2 Microcontroller & Decoder ...2 Display & Keyboard ...4 Mute Circuit ...4 Power Supply ...5 DISASSEMBLY FOR SERVICING ... 6 CHANGE OF MAINS VOLTAGE ... 7 LIST OF DIAGRAMS ... 7 3 ALPHA 5 CD SERVICE MANUAL CIRCUIT DESCRIPTI ON Audio Board The audio board contains the digital filter, DAC, audio output stages and associated power supplies. The required signals from the main board are passed to the audio board via the 18 way connector. This connector carries DAAB, CLAB, WSAB, DEEM, OV, ATSB XSYS, EFAB and +5V line. The DAC requires 3 supply rails to function, +5V, -5V and -15V and also a series of averaging capacitors, (C1-7,C101-107), for the bit switches in each channel of the DAC for good linearity and low distortion. The +5V supply is filtered by RC network R216, C219, C220 and the -15V supply L201 and C224, C225. The output of the DAC is fed to Z1 to convert the output current to a voltage and provide gain. The second ic, Z2, with its associated components forms a low pass 2 pole filter, which combined with the first stage forms a 3 pole Bessel filter. Transistor Q1 is used to switch in additional components if the de-emphasis flag DEEM goes high. This is done automatically when a disc recorded with pre-emphasis is played. The digital output (DOBM) is derived from pin 14 of the digital filter (Z206) and is formed by isolating transformer T201 and associated circuitry. The "Kill" line to mute the audio outputs, with transistors Q2, 102, comes in on the 4th pin of socket SK202 which also carries the dc supplies for the audio board. The audio board is supplied with smoothed +/- 25v D.C via a 4 way connector, SK202. R201,C205 and R202,C206 provides additional filtering before the regulators. There are 4 regulators, +/15V and +/- 5V formed by adjustable regulators Z201,2