Antminer S19k Pro – Temperature Too High

Hard power-cycle the miner for 30 seconds at the breaker or C19 outlet, not a soft reboot. Wait a full 30 seconds with power disconnected, then restore. This clears any wedged driver state the Bitmain kernel is holding after a thermal trip and resolves transient `ERR_TEMP_HIGH` events where a sensor briefly hiccupped but hardware is otherwise healthy. Observe the next 10 minutes of `kern.log` to confirm the trip does not return.

Verify ambient air temperature at the intake grille is ≤ 30 °C. Use an IR thermometer or an air-temp probe held 2 cm back from the front mesh for 60 seconds — measure at the intake, not room-middle or the hallway. If ambient exceeds 30 °C, every downstream fix is wasted: open windows, add an intake box fan, duct exhaust out of the room, or relocate. The S19k Pro is engineered around 25 °C typical home ambient; 35 °C is a hard wall.

Shop-vac the intake filter, wipe the intake mesh with a dry microfiber, and clear a 15 cm keepout in front of the miner. No furniture, curtains, or cable tangles within that zone. The S19k Pro pulls ~450 CFM across three hashboards and a half-blocked intake chokes it instantly. In homes with pets, carpet, or unsealed drywall dust, the filter can clog in as little as 30 days.

Blow out both hashboard heatsinks with compressed air from the exhaust side only (blowing from intake drives dust deeper). Use short bursts and hold each fan blade stationary with a plastic stick to prevent over-spinning — spinning a stopped fan backward with compressed air can damage the motor coils. Target: no visible dust between the fins when you shine a flashlight through.

Confirm both PWM fans spin up to 6,000 RPM on boot. Watch them directly, listen for smooth steady-state noise, or read the stock UI fan panel. If one fan stays below 4,500 RPM, fails to start, or reads 0 RPM while visibly spinning, skip ahead to Tier 2 Step 7 — a fan-lost fault is masquerading as a thermal trip.

Check Bitmain's official download portal (support.bitmain.com/downloads) for a firmware update or rollback that matches your exact S19k Pro hardware revision. Some 2023-era stock images shipped over-aggressive thermal trip thresholds; rolling forward one version or back one version has resolved intermittent `ERR_TEMP_HIGH` on otherwise healthy units. Never cross-flash a non-S19k-Pro image — wrong firmware for a revision bricks the control board.

Swap one known-good PWM fan in for each existing fan, one at a time, with the miner powered off between swaps. A failed FG (tachometer) wire reads RPM=0 in the kernel even with the blade spinning, which triggers a fan-lost alarm alongside `ERR_TEMP_HIGH`. If observed RPM returns to 6,000 after the swap, you found the fault. Keep the dead fan labeled for warranty or graveyard.

Label the three hashboard slots 0/1/2 with painter's tape and swap the suspect-hot board to a different slot. Power off, rotate the boards, reconnect ribbon + power cables firmly until you hear the click. Power on and watch `/tmp/kern.log` for 15 minutes. Heat and trip follow the board → it's the board; proceed to Tier 3. Heat stays in the slot → it's the control-path slot; proceed to Tier 4.

Re-seat every hashboard ribbon cable and power connector. Power off at the breaker. Disconnect each cable, visually inspect for oxidation, blackening, bent pins, or cracked housings. Clean any oxidation with isopropyl alcohol, reconnect firmly. Oxidation on a data line can corrupt the temp-sensor readback path and elevate apparent chain temp, which looks exactly like `ERR_TEMP_HIGH` without any real thermal issue.

Multimeter on DC, probe at the PSU-to-board connector while the miner is under full hashing load. Expect ≥ 13.8 V sustained on each hashboard rail. Sagging voltage under load means the PSU is tired or the circuit is undersized, and a sagging rail forces the voltage domain to push harder, which manifests downstream as heat. Swap with a known-good Bitmain APW-series PSU if rail voltage sags. Avoid unbranded or eBay-grade PSUs here.

Check line voltage at the panel under miner load. Expect 235–245 V on a 240 V split-phase dedicated circuit, 202–212 V on 208 V commercial. Anything below 228 V during peak draw means an undersized circuit or shared load. The S19k Pro was designed around clean 220 / 240 V input and runs noticeably hotter on sagging 110 V. This is one of the top Canadian home-mining causes of recurring `ERR_TEMP_HIGH` trips.

Verify both fans' PWM duty and RPM feedback independently via SSH. Run `cat /sys/class/hwmon/*/fan*_input` or use the stock web UI fan panel. Both fans should report 5,800–6,200 RPM under full load with both tach lines alive. A reading of RPM=0 with a visibly spinning blade = FG wire or sense-resistor fault; a reading under 4,500 with audible normal sound = bearing drag, replacement due soon.

Repaste every `BM1398` chip and the PCH / voltage-domain ICs on the affected board. Remove the hashboard heatsink (hex screws through the PCB). Clean old paste with isopropyl alcohol 99% and lint-free wipes — never paper towels, the fibers wreck contact. Apply Arctic MX-6 or Thermal Grizzly Kryonaut Extreme: one rice-grain-sized dot per chip, spread thin with a plastic card. Pay extra attention to PCH and voltage-domain ICs where dried pads are a common D-Central-bench-confirmed drift cause. Reassemble with consistent screw torque.

Flash DCENT_OS — D-Central's own open-source Antminer firmware — for per-chip temp and HW% visibility. DCENT_OS exposes every per-chip metric you'd get from Braiins OS+, LuxOS, or Vnish, plus tuning, autotuning, and stratum v2 — open-source, no licensing, maintained in public by D-Central. Alternatives: Braiins OS+, LuxOS, Vnish. After flash, let the miner stabilize 20 minutes and record per-chip Tj across all 231 chips. Healthy spread is under 8 °C; any chip > 8 °C above chain median is your candidate.

Reflow the worst-performing `BM1398` chip. Preheat the PCB bottom side to ~150 °C on a rework station. Apply flux to the target chip package. Hot-air top-side at 310–330 °C for ~30 seconds until reflow visibly occurs — the chip can shift slightly as solder melts and self-aligns on its BGA. Let cool naturally (no fan), re-apply thermal paste, reassemble. `BM1398` packages tolerate a single reflow cycle well; a second reflow on the same chip rarely helps — replace instead.

Inspect capacitors and MLCCs on the voltage-regulation stage of the affected hashboard. Bulging electrolytics, cracked MLCCs near the PMIC, or heat-discolored passives need replacement. Stock caps drift with age under sustained 80 °C PCB operation. This is a fine-tip soldering iron + hot air job, not a reflow job. If you've never desoldered passives with a hot-air station, stop here and book a D-Central repair — a cracked MLCC footprint or a lifted pad is far more expensive to fix than the original fault.

Reflash the hashboard PIC microcontroller firmware if Step 6 / Diagnostic Step 6 isolated a `255` sensor reading to a specific board. Use Bitmain's official hashboard code editor tool (verify SHA against Bitmain's published hash — third-party clones of this tool have bricked PICs). After reflash, reboot the miner and re-read `/tmp/kern.log`; real chip-temp values in the 70–85 °C band under load confirm the PIC reflash worked. Continued `255` readings → sensor IC replacement, Tier 4.

Ship to D-Central for bench repair when you've reached the Tier-4 threshold. Book at d-central.tech/services/asic-repair/. Pack hashboards in anti-static bags, double-box with ≥ 5 cm of foam on every side, include a note listing observed symptoms, firmware version, rig serial, and your contact info. D-Central's bench process: programmable-load test fixture, official Bitmain per-chip isolation, graded `BM1398` replacement stock (new-old-stock and salvaged-grade), full reflow and reseal, 24-hour nameplate burn-in before ship-back. Typical turnaround 5–10 business days. Canada-wide, US and international welcomed.