Server PSU Breakout Burnt Wire — 2-Hot 3-Ground Rule

Power off the breakout and miner, unplug from mains, wait 60 seconds for capacitors to bleed. A `1200W` server PSU has bulk caps storing `~30J` — enough to weld a screwdriver. Do not skip this step. If you smell smoke or see char, do not re-energize at all — go to Tier 4 instead.

Inventory: count `PCIe 6-pin` female sockets actually wired between breakout and miner. Calculate the miner's nameplate wall watts × 1.15 ÷ `150W`, round up. That is your minimum port count. Antminer S9 (`1320W`) needs 9-10 ports; L3+ (`800W`) needs 6-7; S19 (`3250W`) needs 22-24 (split between two breakouts/PSUs); Bitaxe (`~25W`) needs 1. If actual is lower than required, stop and add ports before re-energizing.

Replace any pigtail showing browning, melted plastic, or hot-feeling jacket. Do not 're-solder' a cooked connector — the contact pins anneal at heat and lose spring tension permanently. Buy `12 AWG` silicone pigtails from Parallel Miner with verified `2-hot / 3-ground` pinout, or build with a Mini-Fit Jr. crimp tool from known-good pre-tinned silicone wire.

Confirm PSU mains feed. HP DPS-1200 / DPS-1600 / DPS-2400 derate hard on `120V` (DPS-1200 outputs only `~750-900W` on `120V` vs. full `1200W` on `240V`). If you're feeding a `1500W+` rig from `120V` through a server PSU, the PSU is over its `120V` ceiling — switch to `240V` or down-spec the rig.

Run a thermal-camera or IR-thermometer baseline. Topdon TC001 (~`$200 CAD`) or FLIR ONE Pro on a phone is enough. Hash at full nameplate load for 30 minutes, then scan every connector, every wire, every breakout port, the PSU body, the PSU fan exhaust. Healthy: nothing exceeds `~60°C`. Photograph the baseline for future comparison.

Pinout-test every pigtail before plugging. Multimeter on continuity. Pin 1 and Pin 2 must beep together to the breakout's `+12V` bus. Pins 3, 4, 5 must beep together to the breakout's `GND` bus. Pin 6 typically beeps to `GND` (sense). Any deviation = pigtail goes in the bin. Do this even on factory-new pigtails — counterfeits ship in genuine packaging.

Wire-gauge upgrade. Replace any `≤16 AWG` PVC pigtail with `12 AWG` silicone. For S9-class loads, run two `PCIe 6-pin` pigtails in parallel to *each* of the miner's three input plugs — each input needs `~6A`, paralleled pigtails per input give margin. Total `PCIe 6-pin` cable count for an S9 rig: 6 (two per miner input × 3 inputs). For L3+ same math applies.

Re-crimp any factory pigtail you don't trust. Use a Mini-Fit Jr. crimper (Molex 63819-0901 or IWISS clone, `$60-$120 CAD`). Strip `5-6 mm` of wire, crimp the contact, push into the housing until it clicks. Tug-test every pin to `≥30N`. Any pin that pulls out is dead — discard the contact and re-crimp.

Bond grounds. Run a `12 AWG` green wire from the breakout's `GND` lug to the miner's chassis-ground stud, and from the miner chassis to the wall outlet's safety ground (or to a properly bonded subpanel). This protects you when something fails — not 'if'. Skipping this is how miners discover `~100A` fault current with their hand.

Verify `12V` rail under load with the multimeter at the *miner's* `PCIe` input plug (not the breakout). Expect `≥11.8V` sustained at full hash. Less = wire / connector resistance is too high; trace and replace. Voltage drop across each connector pair should be `<50mV` at full current.

Oscilloscope the `12V` rail under load. Bandwidth `≥20 MHz`, probe at the miner input. Expect `<200 mV peak-to-peak` ripple on a healthy server PSU. `>500 mV` = PSU input caps drying, PSU on its way out, or a marginal load step from a misbehaving hashboard. Cheap server PSUs at 5+ years old start ringing — replace before they take down a hashboard.

Schedule recurring thermal scans every 90 days at full hashing load. Photograph and archive each session. Any connector that climbs `>5°C` between sessions is on its way to failure. This is the single most-effective predictive maintenance you can do on a breakout rig.

Run two server PSUs in parallel on a dual-input miner (S19/S21-class). Each PSU feeds half the load. Use a proper dual-PSU breakout with current-share and OR-ing diodes — never just bus-bar the outputs together (one PSU will source slightly higher voltage and carry all the load, defeating the parallel purpose).

Replace cheap Anderson Powerpole / `XT60` adapters with Amass-genuine for breakout-to-PDU or breakout-to-distribution paths. Genuine `XT60` handles `30A` continuous; `XT90` handles `45A`; QS8 / EC5 for `>50A`. Counterfeits derate by `40%` and burn under load — buy from Hobbyking, Amain Hobbies, or Amass-authorized resellers.

Audit circuit-breaker sizing. A `1500W` rig pulling `~12.5A` at `120V` is at the edge of a `15A` breaker. Continuous loads must be ≤`80%` of breaker rating per electrical code → `12A` continuous on a `15A` breaker. If you're pushing it, run a `20A` dedicated circuit (or move to `240V` and the math gets easier). Electrician territory if you're not 100% sure.

Stop DIY: smoke without a known source, pigtail melted into the breakout PCB, wire ignited with visible char, miner won't power on after a connector failure, PSU shows visible burn through chassis vents. Do not re-energize. Photograph damage from multiple angles before moving anything.

D-Central bench process: server PSU tested under controlled DC load bank (`0-1500W` programmable), card-edge pinout verified against model spec, `12V` rail scoped for ripple, dried bulk caps replaced, burnt Mini-Fit Jr. sockets replaced on breakout PCB, bus-bar continuity validated, full-load `24-hour` burn-in under thermal-camera monitoring. If miner suffered collateral damage we triage that separately.

Ship after a fire event: disconnect everything, photograph damage from multiple angles, bag burnt cables and connectors separately from healthy ones (residue is conductive and can short surviving boards). Double-box, foam, ship insured. Include a written timeline of what you saw, smelled, and did. Do NOT re-energize the rig 'to see if it still works' — burnt insulation is unpredictable and the second event is usually worse than the first.