Circuit reference
Panasonic YC-315TR5HGE IGBT Drive Signal Check
Controlled test reference for checking the four IGBT gate-drive outputs before restoring the main inverter power path on a YC-315TR5HGE inverter TIG welder.
Database summary
This page converts the YC-315TR5HGE service procedure into a WelderData drive-check record. The goal is to avoid installing or energizing IGBTs when the driver board, gate harness or bias rails are still wrong.
The test is not a live welding test. It is a staged drive-signal check with the high-voltage power path isolated and the IGBT gate leads removed from the module.
Safe isolation sequence
| Step | Action | Purpose |
|---|---|---|
| 1 | Remove the two cables from the output side of rectifier bridge D1 and insulate them. | Prevents high voltage from being applied across the IGBT C-E path during control-only testing. |
| 2 | Remove the four twisted gate-emitter drive signal leads from the IGBT. | Allows the driver waveform to be checked without depending on a suspect IGBT module. |
| 3 | Power only the control circuit. | Starts the program/driver system without full welding output conditions. |
| 4 | Place a 470Ω / 1W resistor between each G-E measurement pair when using the oscilloscope method. | Provides a defined gate-load condition for waveform observation. |
| 5 | Measure each of the four G-E channels and record all values. | A single missing or asymmetric channel is enough to stop before reconnecting the power stage. |
Waveform and field references
| Evidence point | Reference | Interpretation |
|---|---|---|
| Oscilloscope bandwidth | 100MHz class oscilloscope recommended in the service procedure. | Gate-drive pulses are fast enough that slow meters cannot prove waveform quality. |
| Gate waveform bias | Reference waveform shows a negative drive level around -14V. | Negative turn-off bias helps keep the IGBT off when not commanded. |
| Pulse period reference | Approximate 67µs timing appears in the drive waveform reference. | Use as a platform reference, not a universal TIG inverter specification. |
| 128 line references | 128 to C7- ≈ -11V; 128 to C8+ ≈ +14V. | Field check when an oscilloscope is unavailable. |
| 138 line references | 138 to C5- ≈ -11V; 138 to C6+ ≈ +14V. | Compare with the other drive groups. |
| 108 line references | 108 to C3- ≈ -11V; 108 to C4+ ≈ +14V. | A missing value points to driver, wiring or supply asymmetry. |
| 118 line references | 118 to C1- ≈ -11V; 118 to C2+ ≈ +14V. | Record all four channels before reconnecting the IGBT. |
IGBT offline check before drive testing
The service procedure also separates IGBT device evidence from driver evidence. First inspect the IGBT physically, then check that G1-E1 and G2-E2 are not shorted. A rough 9V battery gate-trigger check can be used to see whether C-E conduction responds to gate bias and then turns off again when gate bias is removed or reversed. Do not treat this as a full semiconductor curve test; it is a field screening step before board-level diagnosis.
| Check | Expected rough result | Stop condition |
|---|---|---|
| G-E resistance | No hard short between gate and emitter. | Any hard G-E short means the IGBT cannot be trusted. |
| C-E state before trigger | No bidirectional hard short. | A C-E hard short means the device must not be installed. |
| 9V gate trigger | C-E conduction changes when gate is biased. | No response can indicate device damage. |
| Gate discharge / reverse bias | C-E returns to off state after gate charge is removed. | If it remains latched or shorted, stop before power testing. |
Replacement warning
When the IGBT is damaged in this platform, the TSM91650 / TSM9165 drive board path may also be damaged. The service logic is to confirm all four drive signals before powering the repaired inverter. Replacing only the IGBT and immediately energizing the machine can repeat the failure.