This playbook gives technicians clear stop rules, substitution rules, and escalation thresholds for WeldKing machines.
| Complaint branch | Stop at setup or accessory correction when... | Swap known-good external parts when... | Internal repair is justified when... |
|---|---|---|---|
| support power, capacitor board, and auxiliary supply | branch power, clamp path, fan wiring revision, or auxiliary-fan behavior clearly explains the complaint | a known-good clamp, holder, or basic torch path still changes the symptom | measured support voltage or high-voltage bus remains wrong with verified input power and external path already proven |
| input-sense, VRD, and mode-state | wrong input class, VRD expectation, or hidden reset behavior explains the low-output complaint |
a cleaner power source or known-good adapter path could still explain wrong voltage recognition | J3 or equivalent sense behavior remains wrong, or display logic remains incorrect after state reset and known-good source proof |
| display, ribbon, and control | connector seating, ribbon seating, or reset behavior clears the complaint | the machine still needs a known-good control branch, torch switch, or simple baseline process | display or control behavior remains wrong with clean seating, reset, and proven baseline process |
| wire-feed, trigger, and feeder | bare-wire feed with tip removed, correct roller family, chart-correct setup, debug-state correction, or spool-gun connection fixes the complaint | a known-good gun, torch, spool gun, or trigger path could still explain the fault | feed or trigger behavior remains wrong after the entire external feed path has been substituted or bounded |
MAG211 chart, solenoid, and spool-gun branch |
chart-correct setup, Bernard front-end rebuild, or a one-gun-only split explains the complaint | a known-good base gun, spool gun, or correct drive-roll family could still explain the fault | solenoid behavior, base-gun proving, and chart-baseline checks are all wrong after the full external path is bounded |
MAG251 ripple and post-service direction branch |
ripple disappears with setup correction or the complaint is really post-service direction error, not a live internal fault | a known-good base gun or corrected external branch still changes the symptom | high ripple or wrong feed direction remains after the external branch is proven and the install or motor-direction path is checked |
MAG255 crater-fill, discharge, and spool-gun-voltage branch |
crater-fill isolation, stop-behavior correction, or spool-gun-only branching explains the complaint | a known-good base gun, spool gun, or correct drive-roll family could still explain the fault | wire creep, discharge-path trouble, or missing pins 1 and 9 behavior remains after the external branch is proven and crater-fill is isolated |
MigSonic145 support-power, trigger-wire, and generation branch |
stable 24 V, a corrected trigger wire, or the right gun and drive generation explains the complaint |
a known-good NT-1 gun, SpoolKing-200 branch, or gas-side package could still explain the fault | startup click-cycling, trigger dead state, or full-speed motor behavior remains after support power and generation-sensitive external branches are proven |
MigSonic252S+SS20 power-source, feeder-package, and spool-gun branch |
source-side state or connection logic explains the complaint before the feeder is opened | a known-good spool gun, drive roll, or feeder-package connection could still explain the fault | frozen readouts, stuck gas, or bad feed remain after the power source baseline and external feeder package are both proven |
| current-path, polarity, and accessory | polarity connector, clamp bite, Dinse seating, or fitted package explains the dead-while-other-processes-work complaint | a known-good clamp, holder, lead set, or official accessory kit is available | the complaint stays with the machine after current path and accessory package are both proven healthy |
CoolTIG220 version, gas, and remote branch |
wrong HF-versus-no-HF assumption, simple DC baseline recovery, gas-path correction, or one remote-only branch explains the complaint | a known-good torch, regulator, hose, or pedal branch could still explain the fault | simple DC TIG still fails after the exact machine version, gas path, torch front end, and remote branch are all proven healthy |
TIG200PACDC DC-baseline, gas, and 4K7 remote branch |
simple DC TIG recovery, gas-path correction, or correct pedal value explains the complaint | a known-good torch, regulator, hose, or pedal branch could still explain the fault | DC TIG still fails after the gas path, torch front end, and correct 4K7 remote branch are all proven healthy |
| TIG start, HF, remote, and gas path | torch polarity, gas flow, tungsten, reset-state, HF-versus-no-HF version assumptions, or one remote-only branch explains the complaint | a known-good TIG torch, pedal, remote, or regulator can still isolate the branch | simple DC TIG baseline still fails with known-good torch, gas path, and control branch |
CoolCut40air internal-air, external-air, and dual-valve branch |
the complaint is bounded to one air mode, or SG55 stack, water-trap, and moisture correction explains the failure | a fresh SG55 stack, dry external air source, or clean clamp path could still explain the fault | both air modes or the proven failing mode still fail after torch stack, clamp, and air-path proof are complete |
ThunderCut65 pressure-window, RV1, torch-head, and guide branch |
pressure-window correction, RV1 adjustment, torch-head rebound correction, or guide-hardware removal explains the complaint |
a fresh A81 front end, dry air path, or clean guide hardware could still explain the fault | no-start, delayed restrike, or bad tracking remains after pressure, pilot-current, torch mechanics, and guide hardware are all proven |
CUT40 hose, valve, CB50, and guide branch |
external-air routing, CB50 front-end correction, clamp cleanup, or guide-hardware changes explain the complaint | a fresh CB50 front end, dry hose path, or guide carriage branch could still explain the fault | no-start or poor transfer remains after torch stack, hose routing, clamp, and guide hardware are all proven |
CUT65 pressure-window, RV1, A81, and torch-head branch |
pressure correction, RV1, A81 front-end replacement, or torch-head rebound correction explains the complaint |
a fresh A81 stack, dry air path, or stand-off or circle-kit branch could still explain the fault | no-start, no-transfer, or unstable pilot remains after pressure, pilot-current, torch mechanics, and A81 hardware are all proven |
| plasma HF, air path, and torch-front-end | fresh front-end stack, clean clamp, correct air-under-flow setup, internal-versus-external air-mode split, or pressure-window correction restores the complaint | a known-good torch or front-end stack can still be substituted | HF, control, or output branch remains faulty after torch stack, air path, clamp, and mode-specific air proof are completed |
| parts, wear-item, and calibration-sensitive | exploded-view or wear-item mismatch explains the complaint after service | a known-good fitted stack, torch, or package-specific part is available | the complaint survives correct assembly order, correct wear items, and the documented baseline or calibration-sensitive setup |
CoolArc160 and related support-power families: do not jump to inverter-board replacement before auxiliary-supply behavior, fan speed, and low-OCV-versus-no-OCV behavior are proven.CoolArc200: low OCV is not enough by itself; decide whether VRD, wrong input-state behavior, or a stalled-fan false fault is normal first.MultiSonic220: if stick and TIG work but MIG does not, keep the diagnosis in polarity, debug state, accessory path, or MIG-only branches before shared power-source repair.PulseWave200: prove simple TIG baseline, torch negative, sane gas flow, and the exact control branch before AC, HF, or calibration-sensitive calls.CoolTIG220: prove the exact HF-versus-no-HF version, simple DC TIG baseline, torch front end, gas path, and one clean remote branch before deeper calls.TIG200PACDC: prove simple DC TIG first, then AC, and verify the documented 4K7 remote branch before treating pedal complaints like board faults.MAG211: keep chart-correct setup, solenoid behavior, and base-gun versus spool-gun proof ahead of random board suspicion.MAG251: keep ripple and post-service feed-direction changes ahead of random board suspicion.MAG255: keep crater-fill, discharge-path, and spool-gun-voltage proof ahead of random board suspicion.MigSonic145: keep stable 24 V, trigger-wire integrity, generation split, and the exact gun branch ahead of random board suspicion.MigSonic252S+SS20: remember the feeder has no PCB; frozen readouts, stuck gas, and source-side weirdness stay in the power source first.CoolCut40air: keep internal-versus-external air-mode proof, dual-air behavior, SG55 stack, and water-trap condition ahead of PCB suspicion.ThunderCut65: keep postflow versus no-start separation, pressure window, RV1, torch-head rebound, and guide-hardware changes ahead of PCB suspicion.CUT40: keep external-air hose condition, valve routing, CB50 front-end condition, and guide carriage changes ahead of board suspicion.CUT65: keep pressure window, RV1, torch-head rebound, and A81 stand-off or circle-kit effects ahead of board suspicion.CoolArc160: a slow or unstable fan can be the earliest proof of a bad auxiliary path, not just a cooling complaint.CoolArc160: low OCV with a live fan-auxiliary problem is not enough evidence for inverter-board replacement.CoolArc200: a healthy machine can still look dead if J3 is reading the wrong input class or if VRD low OCV is being misread.CoolArc200: blink or no-output behavior can still be a fan-related false fault before control-board failure.MultiSonic220: MIG dead while stick and TIG still work is often polarity connector, state, or accessory branch trouble, not proof of a dead shared power section.MultiSonic220: full-speed feed at power-up can still be support power, feedback, or power-board-side logic before main output failure.PulseWave200: no-HF or weak-start complaints can still be torch polarity, too much gas flow, remote-only behavior, or reset-state corruption before HF-board blame.PulseWave200: DC TIG healthy while AC TIG fails is a real branch split; do not collapse that into a whole-machine failure too early.MAG211: poor arc quality that disappears with correct chart setup, fresh Bernard front-end parts, or the right spool-gun branch is not internal evidence.MAG251: high weld ripple is a capacitor-first complaint, and backward feed after board work is a motor or wiring branch before replacement-board blame.MAG255: wire creep after stop is a crater-fill branch first, and sparks at the wire tip without trigger command point to the discharge path before control-board suspicion.MAG255: spool-gun no-weld complaints still need voltage proof at pins 1 and 9 before the gun or transformer is condemned.CoolTIG220: no-start complaints can still be wrong version assumptions, gas-path faults, torch-front-end wear, or remote mismatch before HF or control-board blame.CoolCut40air: internal-air-only weirdness can still be dual-valve contamination or water-trap path trouble before PCB failure.ThunderCut65: normal postflow with no start can still be torch-head rebound, pressure-window error, or RV1 pilot-maintain-current drift before board blame.ThunderCut65: bad tracking or cut quality with healthy power can still be guide carriage, stand-off, or torch-head hardware rather than an electrical fault.