If you work with an Allen & Heath Avantis console long enough, you may encounter the dreaded MCU communication error, typically shown as:

“Unable to connect to main board” error.

This message can be alarming—especially during a show. Below is a practical, technician-friendly guide to understanding the issue, addressing the common causes, and preventing it from happening again.

What the MCU Error Actually Means

On the Avantis, the MCU is the main audio PCB which is responsible for audio processing. Without the board, the desk cannot perform any audio processing.

This is typically caused by:

Firmware mismatch
Corrupted firmware
Hardware failure on the main board itself

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Step-by-Step Troubleshooting Guide

1. Power-Cycle the Console (The Right Way)

A simple restart can clear temporary MCU communication faults.

Power down from the touchscreen, if possible, not by unplugging.
Wait 30 seconds.
Power back up.

If the error reappears immediately after boot, continue below.

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2. Check Your Firmware Version

Firmware mismatches are one of the most common causes of MCU errors—especially after an incomplete update.

Look up the current firmware on Allen & Heath’s website.
Compare it with the console version (if you can access menus).
If you cannot access the UI because of the error, move straight to the USB firmware reload.

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3. Perform a Clean Firmware Reinstallation (USB Boot)

A corrupted or partially written firmware package can cause MCU handshake failures.

How to do a clean reinstall:

Download the latest firmware from Allen & Heath.
Follow the firmware update instructions from Allen and Heath’s website.

Tip: Don’t remove power or USB during the update. Interrupting the process is one of the main causes of MCU corruption.

Tip: Use a FAT32 formatted USB disk if your desk is not reading the firmware update file.