The Blackmagic Design Spares - ATEM Constellation 8K - Mezzanine PCB 2 is a high-density I/O (Input/Output) expansion board found within the internal "stack" of the Constellation 8K.
In a massive switcher like the Constellation 8K, the Main PCB handles the switching fabric and processing, while the Mezzanine boards act as the physical and electrical interface for the 40x 12G-SDI inputs and 24x 12G-SDI outputs. Mezzanine 2 specifically manages a secondary bank of these high-bandwidth connectors.
Core Responsibilities
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12G-SDI Interface: Processes the high-frequency signals for its designated bank of BNC ports. It performs re-clocking to ensure signal integrity over long cable runs.
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8K Data Pathing: In 8K mode, this board handles a portion of the "Quad Link" signals, ensuring that four 12G-SDI inputs are perfectly synchronized to form a single 8K image.
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Tally & Protocol Data: Manages the embedding/de-embedding of tally and camera control data (CCU) for the SDI paths on this board.
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Voltage Regulation: Features localized power conversion to step down the main PSU voltage for the sensitive 12G-SDI transceivers.
When to Replace Mezzanine PCB 2
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Localized Port Failure: A specific block of BNC ports (e.g., Inputs 11–20 or a specific set of Aux outputs) is dead or displaying "digital snow," while the rest of the unit operates normally.
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BNC Mechanical Failure: If the BNC connectors on the back of the unit have become loose or have been sheared off due to cable strain, the entire board is typically replaced to ensure broadcast-level reliability.
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Sync/Timing Issues: Signals on these specific ports fail to "lock" or experience intermittent dropping, indicating a failure of the re-clocking chips on this board.
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System Log Errors: The ATEM Setup Utility reports a "Hardware Error" specifically pointing to "I/O Module 2."
Technical Installation Note
Repair Level: 5 (Expert). 1. Removing Rear Hardware: You must remove the silver hex nuts and washers from every BNC port associated with this board on the rear panel. A $14\text{mm}$ deep-well socket is required.
2. Vertical Extraction: This board is connected to the Main PCB via high-density multi-pin "inter-board" connectors. Warning: You must lift the board perfectly vertically. Tilting it while the pins are still engaged can bend the pins on the motherboard, which is often an unrepairable failure.
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Thermal Management: The 12G-SDI processing chips generate significant heat. Ensure that the thermal pads on the underside of the Mezzanine 2 board are intact and making firm contact with the internal heatsinks or the chassis floor.
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Static Protocol: Work on an anti-static mat with a grounded wrist strap. The transceivers on this board are highly susceptible to ESD damage.
Diagnostic: Mezzanine 2 vs. Main PCB
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It is Mezzanine 2 if: The issue is isolated to a specific bank of SDI ports, but the Multiview, front panel, and software control are all working.
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It is the Main PCB if: The entire unit is unresponsive, won't connect to the network, or the Multiview output shows garbled video across all source windows.
Expert Advice: If you are experiencing signal loss, first use the ATEM Software Control to "Reset" the switcher to factory defaults. Occasionally, internal routing logic can "hang," making a hardware port appear dead when it is actually a software logic error.
Are the errors occurring on a specific set of BNC ports, or are you seeing a "Power Supply" or "System" error on the front LCD?
