AvalonMiner 1246 Maintenance & Repair Guide

Introduction

The Canaan AvalonMiner 1246 is a serious piece of Bitcoin mining hardware that represented a significant step forward for the Avalon lineup when it launched. Pushing 90 TH/s of SHA-256 hashrate at 38 J/TH, the 1246 brought Canaan firmly into the competitive territory of high-performance mining — territory that had been largely dominated by Bitmain’s Antminer S19 series. For home miners, small operators, and anyone who appreciates hardware diversity in the Bitcoin mining ecosystem, the AvalonMiner 1246 is a machine worth understanding inside and out.

What makes the 1246 architecturally interesting is its A3210 ASIC chip — Canaan’s proprietary silicon fabricated on a 16nm process. Each unit packs 114 chips across three hashboards, all coordinated through Canaan’s AUC3 (Avalon USB Converter 3) controller architecture. This is a fundamentally different design philosophy from Bitmain’s approach. Instead of a single control board with an embedded web interface per miner, the Avalon architecture uses an external controller module — the AUC3 — that can manage multiple miners from a single Raspberry Pi or similar host running the AvalonMiner Controller software. For operators running multiple units, this is elegant engineering. For repair technicians, it means a different diagnostic workflow than what you are used to with Antminers.

This guide is your complete field manual for keeping the AvalonMiner 1246 running at peak performance. We cover everything from routine dust cleaning to hashboard-level diagnostics and repair. Whether you are running a single 1246 heating your garage in a Canadian winter or stacking a dozen of them behind an AUC3 daisy chain, this guide gives you the knowledge to maintain your hardware like a Bitcoin Mining Hacker — which is exactly what we are at D-Central Technologies.

Technical Specifications

Before you crack open the chassis, know what you are working with. The AvalonMiner 1246 has a unique architecture compared to Antminers — the external AUC3 controller, the integrated PSU, and the daisy-chain topology all affect how you diagnose and maintain the machine. Study these specs. They will save you time and prevent mistakes.

Avalon 12-Series Family

The 1246 is part of Canaan’s 12-series lineup. While this guide focuses on the 1246, much of the maintenance knowledge transfers across the family:

The 1246 is the most efficient unit in this generation, thanks to the A3210 chip — a refined iteration of the A3206 that squeezes more hashes per watt out of the same 16nm process. If you are choosing between Avalon models in this class, the 1246 is the one you want.

Before You Begin

Safety Warnings

Summary of safety rules:

1. Power off and unplug before any maintenance. Wait 5 minutes for capacitor discharge.
2. Wear an ESD wrist strap grounded to the miner chassis whenever handling hashboards.
3. Let the miner cool for 10+ minutes after shutdown before touching heatsinks.
4. Work in a clean, dry environment — no liquids near the miner, no metal shavings, no conductive debris.
5. Never operate the miner with the cover removed — airflow direction is critical for cooling.
6. Document everything — photograph cable positions and connector orientations before disconnecting anything.

Routine Maintenance

Prevention is cheaper than repair — always. A disciplined maintenance schedule extends the life of your 1246, maintains peak hashrate, and prevents the kind of catastrophic failure that turns a profitable miner into a very expensive doorstop. The A3210 chips are designed for continuous operation, but they demand clean air, proper cooling, and stable power in return.

Recommended Maintenance Schedule

Visual Inspection

Start every maintenance session with a visual once-over. You are looking for early warning signs of problems that will become expensive if ignored:

• Dust accumulation — The 1246 moves a serious volume of air through its four fans. Dust accumulates on fan blades, heatsink fins, and the intake grill. Heavy buildup restricts airflow, raises chip temperatures, and forces fans to spin faster — louder operation and shorter fan lifespan. In dusty environments (garages, basements, workshops), double your cleaning frequency.
• Discoloration on hashboards — Brown or yellow discoloration around components indicates localized overheating. This is a red flag. Check for blocked airflow, failed fans, or degraded thermal paste immediately.
• Corrosion on connectors — Green or white residue on the CAN bus connectors, power connectors, or flat cable pins indicates moisture exposure. Clean with 99% IPA and evaluate your operating environment’s humidity control.
• Physical damage — Bent heatsink fins, cracked PCB traces, loose screws, damaged fan blades. Shipping damage is more common than you think — always inspect a new unit before first power-on.
• Cable condition — Check the flat ribbon cables connecting hashboards to the internal control circuitry. These are fragile. A cable that has been pinched, bent at a sharp angle, or pulled can cause intermittent hashboard detection failures that will drive you crazy during diagnosis.
• PSU area — The integrated PSU sits inside the enclosure. Look for any signs of bulging capacitors, burn marks, or unusual discoloration on the PSU board. A failing PSU can take hashboards with it.

Cleaning Procedures

Dust is the number one enemy of every ASIC miner. Here is how to clean the 1246 properly:

1. Power off and unplug the miner completely. Wait 5 minutes for capacitor discharge and 10 minutes for cool-down.
2. Move the miner to a well-ventilated area — you are about to blow a significant amount of dust into the air. Outdoors or in a garage with the door open is ideal.
3. External cleaning first — Use compressed air (or a DataVac electric blower) to blow dust from the intake and exhaust grills. Work from the exhaust side toward the intake to push dust back the way it came in.
4. Remove the chassis cover — Unscrew the top cover screws (typically 4-6 Phillips screws). Set them aside in a magnetic tray so you do not lose them.
5. Clean the fan blades — Hold each fan blade steady with a finger (to prevent the motor from spinning freely during air blasting, which can damage bearings) and blow compressed air through the blades. Clean both sides.
6. Clean the heatsink fins — Blow compressed air through the heatsink channels, working in the same direction as normal airflow. This dislodges dust that has settled between the fins. For stubborn buildup, use a soft-bristle anti-static brush first, then compressed air.
7. Clean the hashboards — Gently blow compressed air across the hashboard surfaces. Pay attention to the spaces between components and around the flat cable connectors. Never use liquid on the hashboards.
8. Clean the PSU area — The integrated PSU collects dust too. Blow it out carefully, paying attention to the area around the power input connector.
9. Reassemble — Replace the cover, tighten screws, and reconnect power and CAN bus cables. Power on and verify normal operation on the AUC3 controller dashboard.

Thermal Paste Replacement

Thermal paste degrades over time, especially under the sustained heat loads of continuous mining. On the AvalonMiner 1246, degraded thermal paste manifests as gradually rising chip temperatures while ambient conditions remain unchanged. If your chip temps have crept up by 5–10°C over several months, thermal paste replacement is likely overdue.

1. Power off, unplug, wait, cool down — the standard safety protocol.
2. Remove the chassis cover and carefully remove the heatsinks from the hashboards. The heatsinks are secured with screws — remove them in a diagonal pattern to avoid warping the boards.
3. Clean old thermal paste — Use 99% IPA and lint-free cloths to thoroughly remove all old paste from both the chip surfaces and the heatsink contact surfaces. Take your time. Residual old paste degrades the performance of new paste.
4. Apply new thermal paste — Apply a thin, even layer to each chip surface. The A3210 chips are relatively small, so a small dot in the center of each chip (which will spread when the heatsink is pressed down) works well. Do not over-apply — excess paste can squeeze out and create short circuits between components.
5. Reinstall heatsinks — Press down evenly and tighten screws in a diagonal pattern with consistent torque. The goal is even pressure across all chips.
6. Reassemble and test — Power on and monitor temperatures for the first hour. You should see a noticeable drop in chip temperatures — typically 5–15°C improvement with fresh high-quality paste.

Fan Maintenance

The AvalonMiner 1246 uses four 120mm × 38mm fans — two intake on one side and two exhaust on the other. Fan failure is one of the most common issues with any ASIC miner, and on the 1246 a single failed fan can cause the entire machine to thermal throttle or shut down.

• Listen for bearing noise — A healthy fan hums smoothly. A failing bearing produces a grinding, clicking, or rattling sound. This noise typically worsens over time and predicts complete failure within weeks to months.
• Check RPM readings — The AUC3 controller software reports fan speeds. All four fans should be running within 10% of each other at the same temperature. A fan running significantly slower than the others is failing.
• Keep blades clean — Dust-caked fan blades are unbalanced blades, and unbalanced blades destroy bearings faster. Monthly blade cleaning extends fan life significantly.
• Fan replacement — The 1246’s fans connect via standard connectors. To replace, power off and unplug the miner, remove the chassis cover, disconnect the fan cable from the board, unscrew the fan from its mounting position, install the replacement, and reconnect. Always use fans with matching specifications — mismatched fans create airflow turbulence that reduces cooling efficiency.

Diagnostics & Troubleshooting

The AvalonMiner 1246’s diagnostic workflow is different from Antminers because all monitoring flows through the external AUC3 controller. You do not SSH directly into the miner — you connect to the Raspberry Pi (or host device) running the AvalonMiner Controller software. Understanding this architecture is critical for effective troubleshooting.

LED Status Indicators

The AvalonMiner 1246 has an LED indicator located on the front panel near the Ethernet/CAN bus connector. This is your first diagnostic signal — learn to read it:

AUC3 Controller Diagnostics

All meaningful diagnostics on the AvalonMiner 1246 happen through the controller interface. Here is how to access it and what to look for:

# Connect to the Raspberry Pi hosting the AUC3 controller
ssh root@<raspberry-pi-ip>

# Check CGMiner (AvalonMiner Controller) status
screen -r cgminer

# If no screen session, check the process
ps aux | grep cgminer

# View CGMiner API output for device status
echo '{"command":"devs"}' | nc localhost 4028 | python3 -m json.tool

# View per-module statistics
echo '{"command":"estats"}' | nc localhost 4028 | python3 -m json.tool

# Check specific miner in a daisy chain (module 0 = first miner)
echo '{"command":"asccount"}' | nc localhost 4028

The estats command output is your most valuable diagnostic tool. It reports per-module data including:

• MMID — Module ID (identifies which miner in the daisy chain)
• DNA — Unique hardware identifier for each hashboard
• Temp — Chip temperature readings for each hashboard
• TMax — Maximum temperature recorded
• Fan — Fan speed percentages
• GHSmm — Hashrate per module in GH/s (should be approximately 30,000 GH/s or 30 TH/s per hashboard)
• ASIC status string — A sequence of characters representing each chip. “o” means working, “x” means failed/missing

# Healthy hashboard — all 38 chips reporting:
# oooooooooooooooooooooooooooooooooooooo

# Hashboard with 2 dead chips:
# ooooooooooxooooooooooooooooxooooooooo
#            ^                ^  = dead A3210 chips

# Hashboard not detected:
# (no entry in estats output for that module)

Common Error Codes & Conditions

Hashboard Testing

When the controller reports a missing or underperforming hashboard, systematic testing identifies whether the problem is the hashboard itself, the flat cable, the power connection, or the control circuitry:

1. Swap flat cables — Move the suspect hashboard’s flat cable to a slot used by a known-good hashboard. If the problem follows the cable, replace the cable. If the problem stays with the slot, the issue is upstream.
2. Swap hashboard positions — If cables check out, physically move the suspect hashboard to a different position in the chassis. If the problem follows the board, the hashboard itself is faulty.
3. Check power delivery — Use a multimeter to verify voltage at the hashboard power connector. You should see the expected DC voltage (typically around 12V). Low voltage indicates a PSU issue. No voltage indicates a blown fuse or broken trace on the power distribution board.
4. Visual PCB inspection — Under good lighting (and preferably with a magnifying glass), inspect the suspect hashboard for burn marks, cracked solder joints, bulging or leaking capacitors, and corrosion. Pay close attention to the voltage regulator area and the connector pins.
5. Individual chip identification — The ASIC status string from estats tells you exactly which chip positions are failing. Cross-reference with the physical chip layout on the hashboard to identify the specific A3210 chips that need attention.

Common Repairs

This section covers the repairs you are most likely to encounter with the AvalonMiner 1246. We start with the simple and work toward the complex. Know your limits — some of these repairs require professional equipment and experience. There is no shame in sending a hashboard to a professional repair shop when the alternative is making the problem worse.

Fan Replacement

Fan failure is the most common repair on any ASIC miner, and the 1246 is no exception. The four 120mm fans are consumable parts — they have bearings that wear out, especially when running at high RPM in dusty environments.

1. Power off and unplug the miner. Wait for cool-down.
2. Remove the chassis cover by unscrewing the top panel screws.
3. Identify the failed fan — match the fan position to the RPM data from the controller. The intake fans are on one side, exhaust on the other.
4. Disconnect the fan cable from its connector on the board. Note the connector orientation.
5. Unscrew the fan from its mounting position (typically 4 screws per fan).
6. Install the replacement fan — ensure the airflow direction arrow on the fan housing matches the original orientation. Intake fans pull air in, exhaust fans push it out. Reversing a fan creates a dead zone in the heatsink that will cook your chips.
7. Secure with screws, reconnect the cable, reassemble the chassis, and power on.
8. Verify on the controller that the new fan is reporting correct RPM and that chip temperatures are normal.

Power Supply Issues

The AvalonMiner 1246’s integrated PSU is one of its defining design features — and also one of the trickiest components to troubleshoot because it is inside the chassis, not a separate external unit like the Antminer’s APW series.

Symptoms of PSU problems:

• Miner does not power on at all — no LED, no fan spin
• Miner powers on but cannot reach full hashrate — voltage drops under load
• Intermittent shutdowns — PSU thermal protection tripping
• Audible buzzing or clicking from the PSU area
• Burn smell from inside the chassis

Diagnostic steps:

1. Check wall power — Use a multimeter to verify your wall outlet is delivering within the 176–264V AC range. Low input voltage is a common cause of PSU-related hashrate drops, especially in areas with unstable grid power.
2. Inspect the power cord and connector — Look for heat damage, melted plastic, or loose connections at the plug. A poor connection generates heat, which creates more resistance, which generates more heat — a destructive feedback loop.
3. Check DC output voltage — With the miner powered on but under light load (one hashboard connected), measure the DC output voltage at the hashboard power connectors. It should be approximately 12V DC. Significant deviation indicates PSU failure.
4. Listen and smell — A buzzing PSU is usually failing. A burning smell means stop immediately, unplug, and inspect for damage.

Hashboard Issues

Hashboard problems range from simple (loose cable) to complex (failed ASIC chips requiring BGA rework). Start with the simple causes and work your way up:

Hashboard not detected:

1. Reseat the flat ribbon cable at both ends — the hashboard connector and the control board connector.
2. Try a different flat cable (if you have a spare or can borrow from a known-good connection).
3. Check the hashboard power connector — a loose power connection can prevent the hashboard from initializing even though it has data connectivity.
4. Visually inspect the hashboard connector pins for bent or corroded pins.
5. If the hashboard is detected in a different position, the original position’s control circuitry may be damaged.

Low hashrate on a single hashboard:

1. Check the ASIC status string from estats to count working versus failed chips.
2. If only 1–2 chips are marked “x”, the hashboard is still usable but underperforming. The failed chips will not recover on their own.
3. Check chip temperatures — if specific areas are running hot, thermal paste may have failed in that zone.
4. Inspect the voltage regulator components on the hashboard for signs of failure (burn marks, bulging capacitors).
5. If multiple chips are failing in a chain pattern, this often indicates a signal chain issue — the CK (Clock), C (Clock Transmit), R (Reset), or D (Data) signal path may be interrupted by a single failed component.

Understanding the A3210 signal chain:

The ASIC chips on each hashboard are organized in series-connected groups. Four key signals flow through the chain:

• CK (Clock) — 25 MHz working clock for each chip. Drives the hashing operations.
• C (Clock Transmit) — 5 MHz synchronization clock transmitted between chips to keep the chain coordinated.
• R (Reset) — Reset signal for chip initialization. A broken reset chain prevents downstream chips from starting.
• D (Data) — Data bus for mining work distribution and nonce results. A break here means downstream chips receive no work.

When a chip fails in the signal chain, all chips downstream of it in that particular series group may also stop functioning — even though the downstream chips themselves are healthy. This is why a single failed chip can kill the hashrate contribution of an entire chain segment. Identifying the first failed chip in the chain is critical for efficient repair.

Network & Controller Issues

Because the AvalonMiner 1246 relies on the external AUC3 controller, network and controller problems are a distinct failure category:

AUC3 not detecting miners:

1. Check the USB connection between the AUC3 and the Raspberry Pi. Try a different USB port. Try a different USB cable.
2. Check the CAN bus cable between the AUC3 and the first miner in the daisy chain. These cables are the lifeline of the Avalon architecture — a single bad cable breaks communication to every miner downstream of it.
3. Verify the AvalonMiner Controller software (CGMiner) is running on the Raspberry Pi. Restart it if necessary.
4. If using a daisy chain of multiple miners, disconnect all but one miner to isolate the problem. Reconnect them one at a time to find the unit or cable causing the issue.

Intermittent connectivity:

• CAN bus cables are susceptible to EMI (electromagnetic interference). Route them away from power cables and other sources of electrical noise.
• Corroded CAN bus connectors cause intermittent drops. Clean with 99% IPA and a small brush.
• In large daisy chains (10+ miners), signal degradation can occur toward the end of the chain. If the last few miners in the chain are unreliable, shorten the chain or add a second AUC3.

Firmware & Software

The AvalonMiner 1246’s firmware lives on the miner’s internal memory, but all firmware management happens through the controller. Canaan also provides the FMS (Farm Management System) software for large-scale deployments.

Firmware Updates

Canaan releases firmware updates to improve performance, fix bugs, and address security issues. Here is how to update:

1. Download the latest firmware from Canaan’s official website. Always verify you are downloading from the legitimate Canaan site — firmware from unofficial sources can contain malware that redirects your hashrate to someone else’s wallet. Trust no one. Verify everything.
2. Verify the firmware file matches your specific model — AvalonMiner 1246. Do not flash firmware intended for other Avalon models.
3. Access the AvalonMiner Controller web interface on the Raspberry Pi (typically at the Pi’s IP address on port 4028 or via the web UI).
4. Navigate to the firmware upgrade section and upload the firmware file.
5. Select the target miners — you can upgrade individual miners or batch-upgrade all miners connected to the AUC3.
6. Wait for the upgrade to complete — the LED on the miner will flash blue during the process. Do not interrupt power or disconnect cables during a firmware flash. A bricked miner from an interrupted flash is a real and expensive possibility.
7. Verify the upgrade — check the firmware version reported in the controller software after the miner reboots.

Batch Upgrades Using FMS

For operators managing many AvalonMiners, Canaan’s FMS (Farm Management System) software is the right tool for firmware management:

1. Download and install the latest FMS from Canaan’s website.
2. Connect your computer to the same network as your AUC3 controllers.
3. Launch FMS and let it scan the network — it will discover all AvalonMiners via the AUC3 controllers.
4. Select the miners you want to upgrade (you can filter by model and current firmware version).
5. Upload the firmware file and initiate the batch upgrade.
6. FMS handles the sequencing automatically — it will not overload your network by upgrading all miners simultaneously.

Factory Reset

When configuration issues are causing problems and you cannot resolve them through the controller interface, a factory reset returns the miner to its default state:

1. Power off the miner and disconnect the power cable.
2. Locate the reset button on the back of the miner, near the Ethernet/CAN bus port.
3. Press and hold the reset button for 5 seconds, then release.
4. Reconnect power and turn the miner on.
5. Wait approximately 4 minutes for the factory reset to complete. The LED will flash blue during this process.
6. Reconfigure the miner through the AUC3 controller — pool URLs, worker names, and performance settings will all need to be re-entered.

Configuration Best Practices

Optimizing your AvalonMiner 1246 configuration is the difference between running at 90 TH/s reliably and fighting constant instability:

• Set multiple mining pools — Configure at least three pools (primary, secondary, tertiary) in the controller. If your primary pool goes down, the miner automatically fails over to the next pool. Zero-pool downtime means zero wasted hashrate.
• Use stratum+tcp protocol — Ensure your pool URLs use the stratum protocol for optimal communication efficiency.
• Monitor temperature thresholds — The default temperature limits in the controller software are reasonable, but if you are running in a controlled environment (like a dedicated mining room), you can tighten them to catch problems earlier.
• Keep firmware current — Check for updates quarterly. Canaan periodically releases performance improvements and security patches.
• Document your configuration — Keep a text file or spreadsheet with every miner’s configuration: IP address, pool settings, firmware version, physical location. When you have 20 miners on a single AUC3, this documentation saves hours during troubleshooting.

Component Deep Dive — Hashboard Architecture

For those who want to understand what they are looking at when they open up a 1246 hashboard, this section covers the internal architecture. This knowledge is invaluable for advanced diagnostics and makes you a more effective communicator when describing problems to a repair technician.

A3210 ASIC Chip Layout

Each of the three hashboards in the AvalonMiner 1246 carries 38 A3210 ASIC chips, totaling 114 chips per miner. The chips are organized into groups connected in series, with multiple chips running in parallel within each group. This series-parallel topology means:

• A single chip failure in a series group can take out the entire group’s contribution to hashrate.
• Parallel groups provide some redundancy — losing one group reduces hashrate proportionally but does not kill the entire hashboard.
• The signal chain (CK, C, R, D) flows through the series connections, so a chip failure that breaks the signal chain has cascading effects downstream.

Power Delivery Architecture

The power delivery system on the 1246’s hashboards uses multiple voltage rails:

• Vcore — The core voltage that drives the A3210 hashing engine. This is the most power-hungry rail and the one most affected by voltage regulator failures.
• VTOP — Top-side voltage for chip I/O and communication circuits.
• VDDIO — I/O voltage for the data communication bus between chips.

Each voltage rail is supplied by dedicated voltage regulators on the hashboard. These regulators (typically MOSFET-based buck converters) are the second-most-common point of failure after fans. Signs of regulator failure include:

• Burn marks or discoloration around the MOSFET area
• Bulging or cracked capacitors near the voltage regulators
• A section of chips all going dead simultaneously (they share the same regulator)
• Abnormal power draw reported by the controller

Management Module (MM) Board

The MM board is a small circuit board on each hashboard that acts as the communication bridge between the hashboard’s ASIC chips and the AUC3 controller. The MM board handles:

• Work distribution from the mining pool to the ASIC chips
• Nonce collection from chips that find valid hashes
• Temperature monitoring and fan speed regulation
• Firmware storage and execution

MM board failures are relatively rare but cause the entire hashboard to disappear from the controller. If a hashboard is not detected and you have ruled out cables and power, the MM board is the next suspect.

Operating Environment Optimization

The AvalonMiner 1246 is rated for operation between −5°C and 35°C at 5–95% relative humidity (non-condensing). But “rated for” and “optimal for” are different things. Here is how to set up your environment for maximum performance and longevity:

• Temperature sweet spot: 15–25°C ambient — In this range, the fans run at moderate speed (quieter, longer lifespan), chips operate at optimal efficiency, and you have plenty of thermal headroom before throttling kicks in.
• Airflow is everything — The 1246 needs clear intake and exhaust paths. Do not push miners against walls. Leave at least 30cm clearance on the intake and exhaust sides. For rack deployments, hot-aisle/cold-aisle separation dramatically improves cooling efficiency.
• Humidity control — Below 30% RH, static electricity risk increases. Above 70% RH, condensation risk increases during temperature swings. Aim for 40–60% RH. In Canadian winters, indoor air is often very dry — a humidifier in your mining space protects against ESD.
• Dust filtration — If your mining environment is dusty, consider adding intake filters. A 20 PPI reticulated polyurethane foam filter on the intake side dramatically reduces internal dust buildup. Replace or clean filters monthly.
• Power stability — The integrated PSU handles a wide voltage range (176–264V AC), but voltage fluctuations still stress components. If your grid power is unstable, consider a line conditioner or UPS. Clean, stable power extends the life of every component in the miner.

Frequently Asked Questions

When to Call a Professional

This guide covers a lot of ground, but some repairs require professional equipment, training, and experience. Here is when to stop DIY and call D-Central:

• Dead ASIC chips — Replacing A3210 chips requires BGA rework stations, thermal profiling, and precision soldering. One wrong move and you damage the PCB traces, turning a chip-level repair into a board-level replacement.
• Voltage regulator failure — MOSFET driver replacements require identifying the correct component values and precise soldering. The wrong component or a bad solder joint can cause the entire hashboard to short.
• PSU internal repair — The integrated PSU handles high-voltage AC. Internal PSU repair is dangerous and requires isolation equipment and high-voltage test gear.
• Multiple hashboard failures — If more than one hashboard is failing simultaneously, the root cause may be the PSU, the power distribution board, or an environmental issue that needs professional diagnosis.
• Firmware corruption — If a factory reset does not recover normal operation and the miner will not accept firmware updates, professional JTAG or serial recovery may be required.

Interactive Hashboard Schematic

Explore the AVALONMINER 1246 hashboard layout below. Toggle layers to isolate voltage domains, signal chains, test points, key components, and thermal zones. Hover over any region for quick specs — click for detailed diagnostics, failure modes, and repair guidance.