ESAB Cadd Tig 1500i TA34, Service Manual

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S0740 800 186/E080826/P50
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ct33f3gate
Checking the gate pulses
When checking the gate pulses, the machine can either be in soft--start mode or in normal
operation mode.
Special equipment
To measure the gate pulses, you need a gate pulse load. This is included in soft--starting
tool SST 3, which is described on page 36.
Instructions
1. Disconnect the machine from the mains.
2. Disconnect connector 20XS5 from terminal G on control board 20AP1.
3. Connect the gate pulse test cable of the SST 3 to terminal G on control board 20AP1.
Measuring connection for the gate pulses
4. Switch on the machine.
5. Connect an oscilloscope to the SST 3, with the probe to terminal G2 and the screen to
terminal G1 of SST 3.
6. Set the machine to MMA welding mode.
7. Measure the pulse frequency. It must be 65 kHz +/-- 1kHz.
8. Measure the duration of the negative pulse. It must be 41 -- 43 % of the cycle time,
measured at a voltage level of --10 V.
9. The waveform of the pulses must be as shown below.
Gate pulses from circuit board 20AP1