Arcam AVR400 service manual

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It communicates with the Input Board via CN101 and a 31 way ribbon cable. Other connectors comprise CN94 which connects to two secondaries of the main power transformer and the hard wired BN93 which connects up the daughter board.

There are two associated break off boards. One houses the front panel mounted single pole mains switch plus its suppression capacitor C901 and a connector BN502. The second is mounted on the power amplifiers’ heatsink and is used to route power to the cooling fans and also to guide the 31 way ribbon cable.

The VFD draws AC filament power from a centre tapped winding of the power transformer connected to pins 1, 2, and 3 of CN94. The centre tap connects to ground via the zener diodes D901/2 and C903 to provide the filament with its required DC offset. Pins 4 and 5 connect to a relatively high voltage transformer secondary which is half wave rectified by D916 and smoothed by C907 and C960. The zener diodes D903 and D904 in series with R906 generate +40V which is then coupled to the emitter follower Q901 to provide a nominal regulated 40V HT power rail for the VFD.

The VFD’s internal driver IC and external data bμFfer IC901 run from the main +5V supply generated in the Power Supply board and routed onwards through the Input Board. The drive signals (data, clock, chip select and reset) come directly from the system microprocessor via CN101.

The 12 front panel switches are arranged in 2 blocks of 6 with resistive divider chains connected to two ADC inputs on the system micro. These have 10K pull-up resistors at the system μP end to complete the potential divider chains. The pnp switching transistors Q906 and Q907 turn on the 3V3 supply from the system μP via another 10K pull-up resistor at the μP end to provide interrupt control.

The power status LED D905 is a tri-colour type. The green side indicates power on and the red side standby. A high signal on the LED net turns on Q902 and Q903. This turns off the npn Q913 to disable the red LED and turns on the pnp Q912 to enable power to the green LED. The reverse is true when the LED line is low. Pulling the STB(LED) line low when the LED line is also low powers both LEDs and gives a yellow light to show when the unit is booting up. Note that the power supply is STBY+5V to allow the red LED to operate in standby mode.

RC901 is a Kodenshi KSM603TH5B encapsulated infra red receiver for processing commands from an external IR remote control. It is designed to work with the 36-38kHz carrier frequencies associated with the Philips RC5 protocol. Note that it operates from the ST+5V rail to enable the AVR400 to be woken up. It does not demodulate the IR – this is done by the system microprocessor.

The headphones amplifier IC902 drives external headphones directly via the 330μF series capacitors C935 and C936. IC902 has a gain of about 4, meaning that the headphones output will be about 4V rms when the volume control is set to clip the L and R main power amplifiers (equivalent to about 120WPC into 8 ohms). IC902 is a JRC NJM5556AL capable of driving 7V rms into150 ohm loads and about +/- 100mA peak current into lower impedances. Mute transistors Q904/905 in series with 100R resistors are fitted in front of its input to minimize switching transients and it is powered from the +/-15V supplies generated on the Power Supply Board.

The L and R headphones outputs go via BN93 to the Headphones Board, after passing through relay RL902 which is normally off. A positive voltage from the μP at the emitter of pnp Q911 turns on Q911 and generates the same positive voltage at the base of the npn transistor Q909. Because its emitter is connected to the -15V rail this pulls the relay on.

The FRONT AUX and MIC inputs come from the Headphones Board and through the microphone relay RL901. When the relay is off the AUX line level L and R signals are switched through to the unity gain bμFfer IC904 and then on to the Input Board via pins 3 and 1 of CON101. When the relay is closed (in

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Contents Issue AVR400 Main Assembly Transformer Power Power PCBs + Feet Rear Panel + PCBs AVR400 Power Amplifier Circuit Description Page AVR400 Main Power Supplies Circuit Description AVR400 Front Panel Board Circuit Description Page Analogue inputs, volume control and outputs AVR400 Input Board Circuit DescriptionSpdif inputs, ADCs, DACs and Audio DSPs Page System Control Microprocessors AVR400 RS232 board AVR400 Hdmi Input/Output Board Page Page AVR400 Analogue Video Board Vfdrst CN101Vfdclk 25 27 29 24 26 28Page Page Page Page 8V Total 904.33mA TTL Output ADV7844Hdmi 24/30/36Bit Change Value 33ohm--0ohm FLI30336 Worst Measured CurrentsConnect pin3 OE1 OE2 S1 S0Input Output GNDSCALER&AnalogREG Adcreg 1.8/3.3VFRONTHDMIOption Schematic Diagram SBL IC83 IC81NJW1321FP1 LC74763M+15V 8CH Lch JK79 8CH Rch8CH SLch 8CH SRch 8CH Cch JK78 15VScrew Mark
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AVR400 specifications

The Arcam AVR400 is a high-performance AV receiver designed to provide an immersive home theater experience. As part of Arcam’s esteemed lineup, the AVR400 combines advanced technology with exceptional sound quality, catering to audiophiles and home cinema enthusiasts alike.

At the heart of the AVR400 is its impressive power amplification, providing 100 watts per channel across 7 channels, ensuring a robust performance capable of driving a wide range of speakers. This power output is complemented by a high-current design, which means the receiver can handle dynamic audio passages without distortion, offering clarity in both subtle and explosive soundtracks.

One of the standout features of the AVR400 is its support for various surround sound formats, including Dolby TrueHD and DTS-HD Master Audio. This allows for an unparalleled audio experience, transporting users right into the heart of the action. Additionally, the AVR400 is equipped with the latest HDMI inputs, ensuring compatibility with a multitude of high-definition sources, including Blu-ray players, gaming consoles, and streaming devices.

The AVR400 also boasts advanced video processing capabilities, supporting 4K pass-through as well as upscaling of lower-resolution content to 4K. This makes it an ideal choice for users looking to future-proof their home theater setup, as it can seamlessly integrate with modern 4K televisions while enhancing the quality of older content.

User-friendliness is another essential characteristic of the Arcam AVR400. It comes equipped with an intuitive on-screen menu system that simplifies the setup process. The inclusion of an automatic calibration system helps optimize speaker settings in accordance with the room acoustics, ensuring users achieve the best sound possible from their setup.

Furthermore, the network features of the AVR400 allow for streaming audio from various online services and wireless devices. Built-in support for DLNA enables users to access their media library wirelessly, while the USB input allows for direct playback from flash drives or external hard drives.

In terms of build quality, the Arcam AVR400 embodies the brand’s commitment to excellence. With a sleek design, high-quality materials, and an engineered chassis that minimizes vibration and interference, the AVR400 is not only visually appealing but also built to deliver performance over time.

In summary, the Arcam AVR400 is a feature-rich AV receiver offering a perfect blend of power, precision, and versatility. Whether for movie nights or music listening, it stands out as a reliable choice for those seeking high-quality audio and video reproduction in their home entertainment systems.
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