Bitaxe Hex XT30 Inrush Trips Bench PSU

Read your supply label and confirm continuous current rating. 12.0 V (NOT 5 V, 9 V, 19 V), 5 A minimum continuous, name-brand regulated. If you are using a lab/bench supply, read the current-limit setpoint - anything below 6 A will trip on Hex inrush. Class-A continuous wall-warts should label 'continuous' or have a thermal rating that matches the current rating; cheap 'peak' labels are misleading. Knowing what supply class you are working with frames every step below.

Bump the bench supply current limit to 6 A for power-on. Korad / Riden / BK Precision lab supplies allow live adjustment. Set the current limit to 6 A, plug in the Hex, watch it boot cleanly, then drop the limit back to 4 A for steady-state if you want overcurrent protection during runtime. The Hex actual steady-state draw is ~2.5 A at stock and 4-5 A at aggressive OC, so 4 A is reasonable for runtime protection and 6 A is plenty for inrush headroom.

Try a known-good 12 V / 5 A+ continuous wall-wart. Borrow from a known-working Bitaxe / Hex setup, or use D-Central PSU bundle. If the Hex boots cleanly on the borrowed supply, your original supply is undersized for inrush - even if it is spec-rated 5 A continuous, its inrush headroom may be too tight. This single A/B test resolves about half of all 'Hex won't power up' tickets.

Cycle power slowly and watch for a 'click then nothing' pattern. Plug-in. If you hear an audible click or relay sound from a wall-wart followed by silence, the wart internal protection latched off on inrush. Some warts auto-reset after ~30 seconds of being unplugged; some require unplugging and replugging multiple times to clear the latch. Repeated cycling damages the wart protection circuit; at three trips, replace the supply rather than continuing to abuse it.

Stagger multi-Hex stacks at AC mains. If you are powering several Hex units off one outlet via a strip, plug them in one at a time with 3-5 seconds between each. AC-side inrush on synchronous-start can trip a 15 A breaker even though the steady-state load is well under breaker rating. Mean Well RSP-series QA documents this for their entire continuous-output supply line; the same physics applies to any PSU with input rectifier + bulk cap. Switched-outlet power strips that energize sequentially solve it permanently.

Measure the wall-wart actual output voltage at plug-in vs steady-state. DMM on V DC at the XT30 board side. Healthy: 12.00 V open-circuit, drops momentarily to 11.5-11.9 V at plug-in, recovers to 12.00 V within ~50 ms. Failing: drops to 5-9 V at plug-in and either stays low or recovers slowly. A DMM averages, so it will not show the actual ~500 us inrush peak, but a sustained sag below 11.0 V is enough to confirm the supply is not holding rail under load - replace.

Insert a Kill-A-Watt at the wall to log AC-side current. The Kill-A-Watt 'max' reading captures the peak amps drawn during plug-in. Healthy 12 V / 5 A brick at Hex plug-in: max should peak around 1-2 A AC side (steady-state at ~0.6 A AC after Hex is hashing). Anything above 2-3 A AC at plug-in indicates either the brick is grossly undersized, the brick has poor inrush characteristics, or AC mains breaker is on the verge of nuisance-tripping. Also useful for verifying steady-state operation matches the brick continuous-rating spec.

Verify no counterfeit XT30 is amplifying the inrush problem. A counterfeit XT30 with 15-50 mOhm of contact resistance forces the supply to push more current to charge the caps in the same time window - so a marginal supply that would have survived a clean XT30 might trip on a counterfeit one. Quick visual: no Amass logo, mismatched font, sloppy mould lines, magnetic pins = counterfeit. Replace cable with verified-genuine Amass XT30 (D-Central PSU bundle, or sourced from a reputable RC retailer with Amass authenticity documented).

Test with an inline DC fuse holder + slow-blow 7.5 A fuse. This is a diagnostic, not a fix: a slow-blow fuse will survive a 5 A x 500 us inrush spike comfortably, but will blow on any genuine sustained overcurrent above 7.5 A. If the fuse blows at power-on, the Hex is genuinely drawing more than spec - damaged cap, damaged TPS546, or board-side short. If the fuse holds and the supply still trips, the supply is the limiting factor. Cheap diagnostic that disambiguates supply problems from board problems.

Scope the inrush waveform with current probe or 0.1 Ohm shunt. Pico TA189 current probe, Tek A6302, or a 0.05-0.1 Ohm precision shunt in series with the 12 V line. Single-shot trigger on Vin rising edge with a 1-2 ms timebase. Healthy: 3-5 A peak for ~200-500 us, exponential decay to ~2.5 A steady within 2 ms. Failing supply foldback: peak clipped at the foldback threshold, cap-charge ramp incomplete, Vin does not reach 12.0 V for 50-200 ms, brownout. Failing Hex (rare): peak goes well above 8 A, indicating cap or regulator damage.

Add a CL-60 NTC inrush limiter inline on the 12 V cable. A Cantherm CL-60 (or equivalent) NTC thermistor: ~10 Ohm cold, drops to <0.1 Ohm after ~5 seconds of conduction. Solder inline on the 12 V (positive) wire of your XT30 cable, heat-shrink for protection. The thermistor limits inrush peak to ~1.2 A at 12 V cold-start, then conducts normally once warm. Cost ~CAD $1-2 per thermistor. Side effect: small steady-state loss (~50-100 mW), totally negligible. This is the cheapest universal fix for any inrush-marginal supply.

Build a soft-start MOSFET circuit (more advanced). P-channel MOSFET in series with the 12 V line, gate held low through an RC network (100 kOhm + 10 uF typical) so the gate slowly ramps from off to on over ~100 ms. Inrush is now bounded by the MOSFET slow turn-on rather than the cap-charge time constant. More elegant than NTC, no warm-up time, no steady-state loss. Schematic resources: Texas Instruments app note SLVA847A on hot-swap soft-start, or community schematics in the Bitaxe Discord channel.

ESR-test the TPS546 input caps. Hex powered off and discharged. Atlas Peak ESR70, MK-328, or equivalent ESR meter. Probe across each input bulk cap (typically two 22-100 uF aluminium polymer + multiple MLCC bypass). Healthy polymer: <50 mOhm. Failing: >100 mOhm ESR points at heat-stressed cap; replace with same value/voltage + low-ESR polymer (Panasonic FP series, Nichicon PCJ series). Hot-air desolder at ~310 C, fresh solder + flux, replace, ESR-test the new cap before declaring repair done.

Replace counterfeit XT30 with genuine Amass XT30-PB through-hole socket. If the cable side is fixed but the board-side socket has been mechanically damaged or has worn leaf contacts increasing local impedance: hot-air desolder the female XT30, solder a fresh genuine Amass XT30-PB through-hole part. Verify alignment before reflow; a misaligned XT30 socket will lift on first cable insertion. Source from Digi-Key, Mouser, or other reputable component distributor - beware counterfeit listings on AliExpress.

Re-flash ESP-Miner-multichip after any board-side rework. Hot-air work near the ESP32-S3 can briefly raise SPI flash temperature and corrupt config silently. After Tier-3 rework, re-flash the correct multichip image via the Bitaxe Web Flasher and verify all six chips enumerate at low frequency before declaring the repair complete. Also verify Vin reads clean (11.95-12.10 V under steady load) in AxeOS as a final check.

Stop DIY and ship to D-Central if any of: your scope shows inrush peak >8 A (board-level damage), ESR meter flags multiple input caps (cascading cap failure), the female XT30 socket is mechanically destroyed (cracked plastic body, lifted pad, snapped leaf), or you are not comfortable with hot-air rework at all. D-Central bench has a calibrated current-probe oscilloscope, ESR meter calibrated against a reference standard, genuine Amass XT30 + Panasonic FP polymer cap inventory, and we have done dozens of Hex inrush diagnostic + repair tickets. Soldering damage to a Hex PCB pad turns a CAD $5 cap into a CAD $300 board replacement; cheaper to ship.

Document and ship to D-Central. Pack the Hex (anti-static bag), include the supply you have been using, attach a note with: scope screenshots if you have them, AxeOS firmware version (or note 'won't boot to record'), what supplies you have tried, what symptoms you observed, what Tier 1-3 steps you ran. The more data you include, the faster we can isolate the failure mode and the cheaper the repair. Canada-wide shipping; US/international welcomed. Turnaround 5-10 business days for a full Hex inrush diagnostic + cap/regulator repair.

Consider the D-Central Hex PSU bundle as a permanent supply. If you have fought inrush trips on multiple supplies, the issue is upstream - the supply chain you have been buying from does not validate inrush behaviour. The D-Central bundle ships a name-brand regulated 12 V / 5 A brick with verified inrush headroom, paired with a tested-genuine Amass XT30 cable, matched to the Hex actual electrical demands. Pioneers of the Bitaxe Hex ecosystem; we would rather sell you the right supply once than diagnose marginal-PSU trips on bench three times.

Log the inrush event for fleet operators. If you run multiple Hex units, log: which supply tripped, which Hex (some Hex units may have slightly higher input cap counts depending on revision), ambient temperature, breaker rating. Patterns across the fleet tell you whether it is one bad supply, one bad Hex, or a systemic AC-mains inrush problem on a shared circuit. Solo-mining lottery stacks especially benefit from a documented power-up procedure that does not risk corrupting NVS on every brownout.

Standardize on one validated supply spec across all Hex units. Once you have identified a supply that powers your specific Hex revision cleanly at cold start, buy it in volume and use it everywhere. Mixing marginal supplies across a stack creates unpredictable startup behaviour - one Hex boots, the next two trip the breaker, the third boots dirty with NVS corruption. One supply spec, validated, repeatable. Mining Hacker rule: solve the failure mode once, not every time you cycle power.

Re-evaluate the supply when Hex hardware revisions change. New Hex revisions may add bulk cap (more inrush) or remove it (less inrush, but more rail noise). When you upgrade Hex hardware, re-validate the supply against the new board with a scope or at minimum a careful A/B power-up test. The supply that worked on Hex v303 is not guaranteed to work on a future v305 with different decoupling. Stay paranoid; the cheapest supply is the one that does not trip your breaker.