Model reference
Panasonic YC-300WP4 AC/DC TIG Welder Repair Reference
Model reference for Panasonic YC-300WP4 AC/DC TIG diagnosis, covering remote-box dependency, SCR output checks, high-frequency supply paths and AC/DC start symptoms.
Database summary
The YC-300WP4 is an AC/DC TIG welding platform with SCR-controlled output, remote-box dependency, AC/DC high-frequency supply differences and water/torch setup considerations. This makes it a useful Panasonic model reference for AC/DC TIG service routing.
Installation and setup checks
| Item | Service note | Faults it can imitate |
|---|---|---|
| Input cable size | Primary input cable should be sized appropriately for the machine. | Low output, overheating or unstable behavior. |
| Gas flow and tungsten size | Flow and tungsten diameter must match welding current. | Poor bead surface, tungsten overheating and arc instability. |
| Work return and torch cable connection | Connections must be tight and low resistance. | HF leakage, no arc, overheated terminals. |
| Remote box | The remote box must be installed; without it the welder cannot be used normally. | Only some crater-fill modes work, or no normal TIG control. |
Main circuit reference checks
| Check | Reference | Interpretation |
|---|---|---|
| Output-terminal resistance | About 450–500Ω between work and torch output terminals. | Abnormal values route toward main circuit or SCR module checks. |
| Output voltage with HF fuse removed | About 80V. | Used to separate output source evidence from HF circuit evidence. |
| SCR gate-cathode resistance | About 25Ω. | Abnormal value supports SCR branch diagnosis. |
| HF transformer secondary | Greater than about 4kΩ. | Low resistance or insulation failure routes toward HF transformer replacement. |
AC and DC high-frequency supply distinction
In AC welding, the HF circuit obtains supply from the AC output path. In DC welding, the HF supply is controlled through the board relay path. This distinction allows a technician to decide whether a no-HF symptom belongs to the P-board control path or the HF generating circuit.