the necessary level shifting. IC73 includes internal charge pumps to convert CMOS logic level inputs to +/-5V RS232 level outputs and +/-25V tolerant RS232 inputs to CMOS logic level outputs. Maximum rated speed is 300kb/sec.

JK73 is a dual mono 3.5mm jack socket providing two +12V trigger outputs Z_1 and Z_2. The series pass transistors Q712/715 are pnp T0-92 types with emitters referred to the +12V rail via the paralleled 4.7R resistors R714/715 and R711/712. In conjunction with the pairs of diodes D711/712 and D714/715 this provides current limiting at approximately 200mA if the trigger outputs are inadvertently shorted to ground.

JK72 is a dual 3.5mm mono jack socket providing inputs for two modulated infra-red remote control signals. These are connected to the opto-isolators IC72 and IC71. Note the use of the standby power supply ST+5V for the subsequent logic.

AVR400 HDMI Input/Output Board

The HDMI Board is described on pages 6 – 10 of the schematics diagrams. Note that it has components fitted to both sides of the PCB. HDMI stands for High Definition Multimedia Interface. The AVR400’s system supports certain parts of the HDMI 1.4a specification (3D video compatibility and Audio Return Channel)

The HDMI Board has 5 type A HDMI input sockets and one type A HDMI output socket, which are flush with the back panel. It gets its power via the hard wired connector and ribbon cable CN61 and com- municates with the Input Board via two flex foil cables attached to connectors CN104 (17 ways) and CN105 (19 ways). It is fitted with a 30 way socket BN301 which attaches to a daughter board handling all analogue video I/O signals (the Analogue Video Board).

The HDMI Board contains 10 separately regulated local power supplies, mostly derived from the unregulated but hum filtered +15V supply on the Power Supply Board. This is input on pins 3 and 4 of the hard wired connector CN61 for +15V and pins 5, 6 and 7 for the ground returns. Pins 1 and 2 are not used. See page 10 of the schematic diagram for all but the last of these supplies, as described below.

IC923, IC927 and IC930 are all Sanken SI-8005Q 3.5 Amps step-down switching regulators operating at 500kHz +/-10% and drawing power from the +15V line. They are used to generate +3.3VDD, +1.8VDD and +1.8VH1 (video processor supply) respectively. The potential dividers in their outputs (R839+R844/ R847, R838+852/R851 and R841+843/840) are used to set the required voltages.

All other local power supplies use linear SM 3-terminal regulators.

IC922 and IC929 provide +2.5VH1 and +2.5VH2 for the two DDR memory chips supporting the video processor. The source supply is +3.3VDD.

IC925 is a KIA7809 generating +8VA from the system’s +15VA line (NOT the unregulated +15V used elsewhere on the board). This is further dropped to +5VA by IC924, a KIA1117S50. Inductor L860 provides decoupling for the +5VH1 line. The video processor digital power supply lines +3.3VH1, +3.3VH2 and +1.8VH2 are sourced from the +3.3VDD and +1.8VDD lines via L-C decoupling.

The video ADC’s analogue supplies, +3.3VA and +1.8VA, are generated from the +5VA line via IC926 (NJM2845DL133) and IC928 (NJM2845L118) respectively.

The 10th regulator, IC917, an NJU7754 found on sheet 9 of the schematic, is used to provide +5V to the HDMI output socket. It is enabled via SW_P+5V and derives its input from the +8VA supply described abov

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Arcam service manual AVR400 Hdmi Input/Output Board
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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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