Antminer S21 Pro Repair — Professional ASIC Repair by D-Central
The Bitmain Antminer S21 Pro pushes SHA-256 mining to 234 TH/s at a remarkable 15 J/TH efficiency — a significant step up from the standard S21. Powered by 195 BM1370 ASIC chips across three hashboards (65 chips per board, organized into 13 domains of 5 chips each), the S21 Pro delivers more hashrate from fewer, more advanced chips. That engineering achievement comes with trade-offs: higher thermal density per chip, tighter operating margins, and repair complexity that demands specialized expertise.
D-Central Technologies has been Canada’s go-to ASIC repair facility since 2016. As the Bitcoin Mining Hackers, we invest in the tools, training, and parts inventory required to service every new generation of mining hardware — including the BM1370-based S21 Pro platform. Our technicians have hands-on experience with the S21 Pro’s hashboard architecture, domain voltage characteristics, and the specific failure patterns that emerge from its high-efficiency design.
Antminer S21 Pro Specifications
| Specification | Details |
|---|---|
| Algorithm | SHA-256 (Bitcoin, Bitcoin Cash) |
| Hashrate | 234 TH/s |
| Power Consumption | 3,510W (±5%) |
| Efficiency | 15 J/TH |
| ASIC Chip | BM1370 (65 chips per hashboard) |
| Total Chips | 195 (3 hashboards x 65) |
| Domain Layout | 13 domains per hashboard, 5 chips per domain |
| Control Board | Amlogic A113D |
| Temperature Sensors | 2 per hashboard |
| Input Voltage | 220–277V AC |
| Cooling | Air-cooled (dual fan) |
| Noise Level | 76 dB |
| Dimensions | 450 x 219 x 293 mm |
| Weight | 18.5 kg |
| Operating Temperature | -20°C to 45°C |
Common Antminer S21 Pro Issues and Symptoms
The S21 Pro’s BM1370 chips are more power-efficient but operate at tighter thermal margins than the BM1368 chips in the standard S21. This means failures can be subtler and more consequential. Here are the issues we see most often:
BM1370 Chip Failures and Low Hashrate
When a BM1370 chip fails, the entire hashboard’s performance degrades — hashrate drops sharply or the board reports 0 TH/s. Unlike the S21’s BM1368, the S21 Pro uses the BM1370BC variant, and a single dead chip in a 5-chip domain can take the entire domain offline. If not addressed quickly, a failed chip can cause cascading damage to surrounding components through voltage irregularities in the domain chain. Our technicians use BM1370-specific chip testers to identify failed chips without unnecessary desoldering.
Overheating and Thermal Throttling
The S21 Pro packs 234 TH/s of hashing power into 3,510W — that is serious thermal density. The machine triggers automatic shutdown when chip temperatures exceed safety thresholds, reporting R:1 error codes. The S21 Pro has only two temperature sensors per hashboard (compared to more on some other models), making it harder for the firmware to detect localized hotspots. Common causes: degraded thermal conductive gel between heatsinks and chips, dust-clogged airflow paths, fan degradation, ambient temperatures above 45°C, and residual flux contamination from previous repair attempts.
Hashboard Detection Failures
If your S21 Pro is detecting only 1 or 2 of its 3 hashboards, the issue typically lies in the connection between the hashboard and the control board. This can be a damaged ribbon cable, a loose connector, or a fault in the hashboard’s communication circuitry. In more serious cases, the hashboard itself may have a fault in its signal chain that prevents the control board from initializing it.
Fan Errors and Cooling System Failures
At 76 dB, the S21 Pro’s fans are working hard. Fan motor wear, bearing degradation, connector damage, or control board fan circuitry faults will trigger fan speed warnings and eventually force a protective shutdown. In high-dust or high-humidity environments, fan degradation accelerates significantly.
Firmware and Control Board Issues
The S21 Pro’s Amlogic A113D control board can suffer from firmware corruption (from power interruptions or failed updates), network interface failures, or NAND flash degradation. Symptoms include boot loops, inability to access the web interface, erratic hashboard detection, and phantom error codes.
PSU and Power Delivery Problems
The S21 Pro requires a stable 220–277V supply delivering at least 3,510W. Undervoltage, voltage fluctuations, or a failing PSU can cause intermittent hashboard dropouts, chip errors, and gradual component degradation. The APW17 is the standard PSU pairing — mismatched power supplies are a common source of hard-to-diagnose intermittent issues.
Our Repair Process
Every Antminer S21 Pro that comes through our doors at D-Central’s Laval, Quebec repair facility follows a structured, transparent workflow:
1. Intake and Visual Inspection
We document your unit’s condition on arrival: physical damage, connector condition, heatsink integrity, dust accumulation, and any signs of previous repair attempts.
2. Full Diagnostic Testing
We run each hashboard through our BM1370 test fixture, checking chip enumeration (all 65 chips per board), domain voltages, temperature sensor readings, and signal chain integrity. The control board is tested for firmware integrity, hashboard communication, fan control, and network connectivity.
3. Detailed Quote
We provide a complete diagnosis with itemized repair costs and estimated turnaround. You approve before any repair work begins — full transparency, no surprises.
4. Component-Level Repair
Our technicians perform precise board-level work: BM1370BC chip replacement using professional BGA rework stations, thermal conductive gel reapplication, heatsink reattachment, LDO and op-amp replacement, signal trace repair, temperature sensor replacement, and control board repair or replacement as needed.
5. Post-Repair Testing and Burn-In
Every repaired hashboard is tested twice on our test fixtures — once immediately and once after cooling — per Bitmain’s recommended verification protocol. The complete unit then undergoes an extended burn-in to confirm sustained hashrate at or near 234 TH/s with stable temperatures across all boards.
6. Secure Return Shipping
Your repaired S21 Pro is professionally packaged and shipped back with a full report of diagnostics and repairs performed.
Repair Pricing
S21 Pro repair costs are determined after our diagnostic process identifies the exact fault. Pricing depends on the number and type of components requiring replacement, the extent of board damage, and the complexity of the repair. We provide an exact quote before proceeding — you are never committed until you approve.
For a preliminary estimate, use our ASIC Repair Cost Estimator.
Why D-Central for Antminer S21 Pro Repair
BM1370 platform expertise. The S21 Pro, S21 XP, and upcoming S21+ all use BM1370-family chips. We have invested in the test fixtures, chip testers, and training specific to this platform. We are not learning on your hardware — we know the BM1370 architecture.
8+ years repairing Antminers. Since 2016, D-Central has repaired thousands of ASIC miners — from S9s to S19XPs to the current S21 generation. That institutional knowledge means faster diagnosis and fewer unnecessary part replacements.
Parts in stock. We carry BM1370BC chips, Amlogic A113D control boards, temperature sensors, LDO regulators, fans, thermal materials, and complete hashboard assemblies for the S21 Pro. In-stock parts mean faster turnaround.
Canadian facility, North American service. Our repair shop is in Laval, Quebec — no international shipping to China or Eastern Europe. Ship from anywhere in Canada or the US and get your miner back fast. Call us at 1-855-753-9997.
Full transparency. Diagnostic report, itemized quote, your approval, then repair. We document every step and stand behind our work with a repair warranty.
Frequently Asked Questions
What is the turnaround time for an S21 Pro repair?
Standard turnaround is 5–10 business days from receipt. Simple repairs (fan replacement, firmware) may be completed in 1–3 days. Complex multi-chip hashboard repairs can take up to 2 weeks depending on parts availability and queue depth. We provide a timeline estimate with your diagnostic report.
Is there a warranty on S21 Pro repairs?
Yes. D-Central warranties all repair work performed. The warranty covers the specific components replaced and the workmanship involved. If the same fault reappears within the warranty period, we repair it at no additional cost.
How should I ship my S21 Pro to D-Central?
Contact us to initiate a repair ticket before shipping. Use the original packaging if available, or a sturdy box with foam padding on all sides. Remove the PSU to save on shipping weight (unless the PSU is part of the issue). Include a description of the symptoms. Ship to our facility in Laval, Quebec — we will provide the exact address when you open your repair ticket.
What does an S21 Pro repair typically cost?
Costs range widely based on the issue. Fan or firmware repairs: $50–$150. Single-chip hashboard repair: $200–$450. Multi-chip or complex board-level repair: $450–$900+. Control board replacement has its own pricing. We always provide an exact quote post-diagnosis. Try our ASIC Repair Cost Estimator for a ballpark.
Can I repair my S21 Pro myself?
The S21 Pro is a precision machine with BM1370BC chips operating at extremely tight domain voltages. Each 5-chip domain operates at approximately 1.04V — there is very little margin for error. Without professional BGA rework equipment, a BM1370 chip tester, and experience with the S21 Pro’s domain architecture, DIY repair risks causing additional damage. We strongly recommend professional service for anything beyond basic fan or cable replacement.
My S21 Pro shows abnormal temperature on only one hashboard — what is wrong?
The S21 Pro has only two temperature sensors per hashboard, so a localized hotspot from a failed chip or degraded thermal paste may not be immediately obvious in firmware readings. If one board shows abnormal temperatures while the others are fine, the likely causes are: damaged thermal conductive gel on that board’s heatsinks, a partially failed chip generating excess heat, a blocked airflow path over that specific board, or a faulty temperature sensor giving incorrect readings. Our diagnostics will isolate the root cause.
Do you sell replacement S21 Pro hashboards?
Yes. If a hashboard is damaged beyond cost-effective repair, we can supply tested replacement hashboards. We also sell individual components (BM1370BC chips, control boards, fans) if you have repair capabilities in-house. Contact us for current availability and pricing.
Get Your Antminer S21 Pro Back to Full Hashrate
At 234 TH/s and 15 J/TH, the S21 Pro is one of the most efficient air-cooled miners ever built. Every day it sits idle is wasted potential. D-Central has the expertise, the BM1370 parts inventory, and the proven repair process to get your miner back online and hashing at full capacity.
Contact D-Central for a repair quote or call us at 1-855-753-9997.