Model family
Panasonic KR CO2 / MIG Welder References
Brand-series repair hub for KR-style CO2/MIG welders, connecting typical fault routing, six-core feeder checks, P-board fuse faults and SCR output evidence.
Database summary
Panasonic KR-style CO2/MIG welders are a useful WelderData reference family because many symptoms are created at the boundary between the wire feeder, gas valve, remote control box, P-board, SCR output module and torch switch loop. A KR machine can appear to have a power-source fault when the actual cause is a feeder cable, fuse, remote potentiometer or P-board protection path.
This page is a brand-series repair hub. Use it to enter the KR-specific diagnostic tables, then return to general MIG/MAG control pages when the fault is not KR-specific.
KR control areas to separate
| Area | Typical function | Fault evidence |
|---|---|---|
| Torch switch loop | Starts gas, wire feed and welding output sequence. | No response, intermittent start, immediate feed without command. |
| Six-core control cable | Carries feeder, gas, command and return signals between machine and feeder. | Gas-only, motor-only, no jog, no current/voltage adjustment or false trigger symptoms. |
| Remote box | Current / wire-feed and voltage setting from the feeder side. | Open-circuit voltage or feeder speed does not respond to knob changes. |
| P-board | Logic, control supply, command processing, feeder/brake control and protection interface. | Fuse faults, D1-D5 damage, Q10 / IC5 / R245 failure, abnormal self-start behavior. |
| SCR module and main output | Controls welding output voltage / power delivery in SCR-based KR platforms. | Low no-load voltage, voltage not adjustable, unstable arc or excessive spatter after control path is confirmed. |
| Wire-feed mechanics | Roller, liner, guide cap, torch cable and contact tip delivery. | Unstable feed, slipping, liner blockage, wire burn-back or poor arc stability. |
KR-specific fault pages
Repair interpretation
If pressing the torch switch gives no no-load voltage and no wire feed, the first evidence should come from the torch loop, feeder plug, control transformer and P-board command path. If wire feed exists and no-load voltage exists but the arc does not start, move the evidence toward output cable, work return, torch/contact-tip condition and SCR output behavior.
If the machine blows FU2 or FU3, do not upsize the fuse. Record whether the failure is linked to the wire-feed motor, gas valve, wet feeder connector, wrong fuse placement, control cable short or P-board diode damage. Oversized fuses can hide the original fault and move the damage into D1-D5, Q10, IC5 or R245.
Typical KR measurement record
| Record item | Evidence to write down |
|---|---|
| Command response | Torch pressed / not pressed; gas yes/no; wire feed yes/no; contactor/no-load response yes/no. |
| Remote adjustment | Does feeder speed change? Does no-load voltage change? Does current/voltage command appear stuck? |
| Fuse state | FU2 / FU3 value, position, whether it blows immediately or after operation. |
| Cable state | Six-core cable continuity, water ingress, pin damage, shorts between control lines. |
| Board evidence | D1-D5 diode state, Q10 resistance, IC5/R245 visible or electrical damage, P-board supply condition. |
| Output evidence | No-load voltage, SCR module evidence, output cable and work return condition. |
KR fault-source classification
For KR-style CO2/MIG welders, WelderData separates faults into three source groups before the P-board is replaced. This keeps remote-box, control-cable and input-power faults from being mistaken for board failure.
| Source group | Typical evidence | Repair interpretation |
|---|---|---|
| Internal machine faults | P-board parts, SCR module, magnetic contactor, control transformer, main transformer, reactor, current transformer or input assembly show abnormal evidence. | Proceed by section: control power first, then command path, SCR output, current feedback and output terminals. |
| External installation faults | Three-phase input outside the 380V ±10% class range, poor grounding, bad work return, output cable damage or wrong feeder connection. | Do not replace internal boards until supply voltage, return cable and feeder interface are verified. |
| Human / service faults | Wrong fuse rating, FU2/FU3 misplacement, remote-box misadjustment, incorrect crater-fill mode, damaged six-core control cable or water in extended cable connectors. | Record the misconnection or incorrect part before replacing P-board parts, otherwise the same fault can return. |
KR 200 / 350 / 500 reference checks
These measurement references help decide whether a KR fault is located in the control-power section, contactor path or main transformer / SCR output section. Treat them as platform references and verify against the exact machine nameplate and service documentation.
| Check | KR reference | What it tells the technician |
|---|---|---|
| Input power | Three-phase 380V class, normally within ±10%. | Input over/under-voltage or phase-loss can imitate P-board and SCR faults. |
| Control transformer secondary | 200V and 20V class control supplies on KR-style control transformer paths. | If these supplies are missing, solve the control-power fault before diagnosing voltage/current adjustment. |
| Magnetic contactor coil resistance | 500KR: about 150–160Ω; 350KR: about 345Ω; 200KR: about 483Ω. | A shorted or abnormal contactor coil can blow the 5A control fuse at power-on. |
| Main transformer secondary no-load reference | 500KR: about 50±1V; 350KR: about 40.7±1V; 200KR: about 28.2±1V. | Useful when tracing low no-load voltage through input phase, SCR module, contactor contacts, transformer and P-board command path. |