The Blackmagic Design Spares - ATEM Constellation 8K - Mezzanine PCB 3 is one of the specialized high-density I/O (Input/Output) expansion boards within the Constellation 8K chassis.
Because the Constellation 8K is a massive 40-input, 24-output switcher, Blackmagic uses a "stacked" mezzanine architecture. While the Main PCB handles the core 8K switching fabric, the Mezzanine 3 board is specifically tasked with managing a localized bank of 12G-SDI connectors on the rear of the unit.
Core Responsibilities
-
12G-SDI Signal Processing: Manages the physical BNC interface for a specific bank of inputs and outputs. It handles signal re-clocking and equalization to ensure 8K data integrity.
-
8K Quad-Link Aggregation: In 8K mode, this board works in tandem with the other mezzanine boards to group four 12G-SDI signals into a single 8K feed.
-
Sub-Switching Logic: Acts as a "pre-processor" for video signals before they are passed to the Main PCB's central crosspoint.
-
BNC Structural Integrity: Provides the physical mounting point for the rear-panel BNC jacks.
When to Replace Mezzanine PCB 3
-
Bank-Specific Failure: Inputs or outputs located in the specific sector managed by "Mezz 3" are showing "No Signal" or digital "sparkles/snow," while all other ports on the switcher work perfectly.
-
Physical BNC Damage: If a cable was tripped over and sheared a BNC connector off the back of the unit, the entire board must usually be replaced to restore those ports.
-
8K Sync Errors: The switcher works fine in HD and Ultra HD, but fails to "lock" onto 8K signals that require the specific ports on this board.
-
Thermal Shutdown: The board's localized voltage regulators or 12G-SDI chips have overheated and failed, often indicated by a specific "I/O Board Error" in the system logs.
Technical Installation Note
Repair Level: 5 (Expert). 1. Chassis Deep-Dive: The Constellation 8K is a 2RU unit packed with boards. To reach Mezzanine 3, you typically have to remove the top cover, the internal cooling shroud, and potentially other mezzanine boards depending on the stacking order.
2. Hex Nut Removal: You will need to remove the silver hex nuts and washers for every BNC connector associated with this board on the rear panel before it can be lifted. A $14\text{mm}$ deep-well socket is recommended.
3. High-Pin Density Connectors: This board connects to the Main PCB via massive multi-pin "bridge" connectors. You must lift the board perfectly vertically. Any tilt during removal or installation will bend the pins on the motherboard, which is often an unrepairable failure.
4. Thermal Pad Replacement: 12G-SDI processing generates immense heat. You must ensure the thermal pads on the chips are replaced or correctly seated against the internal heatsinks or the chassis.
Diagnostic: Mezzanine 3 vs. Main PCB
-
It is Mezzanine 3 if: Only a specific group of BNC ports (e.g., ports 21–30) are failing, but the Multiview and Software Control are functioning normally.
-
It is the Main PCB if: The entire unit won't boot, won't connect to the network, or if the Multiview output is showing garbled video across all windows.
Expert Advice: Before ordering this board, check for bent pins inside the BNC connectors. Sometimes a "No Signal" error is just a damaged center pin in the jack that can be straightened with a needle, saving you a very expensive and complex board swap.
Are the failures occurring on a specific group of BNC ports, or is the entire switcher struggling to process 8K signals?
