Antminer S21 Hashboard Repair Service

Antminer S21 hashboard repair with board-level diagnostics focused on restoring stable chains, accurate sensor readings, and predictable performance under real operating load. 🔧

Model reference: Antminer S21 (SHA-256) is typically rated around 200 TH/s total across 3 hashboards (about ~67 TH/s per board) at roughly 3500 W. At this power density, even minor thermal or signal issues can quickly turn into chain drops or unstable hashing.

These notes summarize common Antminer S21 hashboard failure modes we see during intake diagnostics and board-level service.

Quick Symptom Checklist

• One hashboard drops to 0 hash or becomes unstable after restart
• ASIC count is incorrect or fluctuates under load
• Overheating even with normal airflow and clean fans
• Intermittent behavior: stable when cold, fails after warm-up

Model-Specific Patterns We See on Antminer S21

Red (non-working) ASIC chips often appear on the side of the board closer to the hot air exhaust; overall hashrate drop within a single power domain; hashboard overheating even on brand-new boards due to poor factory thermal paste application; in failure cases, the board is often detected with either 0 ASIC chips or an ASIC count in multiples of 9.

Hardware Notes

• Chips per hashboard: 108
• ASIC marking: BM1368PA; BM1368PB; BM1368AA; BM1368PV; BM1368PM
• Board base: aluminum

Diagnostics Focus

Thermal interface quality verification (with special attention to factory-applied thermal paste, especially blue compounds); identification of degraded ASIC chips and heat-stressed SMD components.

Gotchas

• Parts of the board are covered with protective compound that must be chemically dissolved before repair, adding extra preparation time.
• Thermal deformation of the aluminum base after repeated heating cycles, especially toward the center of the board.

Typical Service Scenario

These boards commonly arrive after long-term operation without regular cleaning or thermal interface maintenance, especially in humid environments or where intake air is dusty or poorly filtered.

What Happens After Intake

After intake, we confirm board revision, verify power domains and sensor lines, isolate the failing chain or domain, perform component-level repair as required, and validate stability under sustained load before return shipment.

Diagnostics & Validation Equipment

We use dedicated hashboard test fixtures and chip-level diagnostic tools, including ASIC REPAIR and STASIC platforms, to validate chain behavior and confirm stable operation prior to final load verification.

Have questions before you ship? Contact our repair team today and get your miner back to full power.