I've checked the couple of threads on here for inspiration, but my problem remains. I haven't used the welder for a few days, and now I've tried to there's no arc. I have no DC across the output, but as the thyristors are awkward to access and need me to dismantle the whole unit I've decided to check the PCB. There doesn't appear to be any gate drive pulse on the ouput of IC4, and the ramp generated at the output of IC 3 is not a clean sawtooth wave but has a high square spike at the peak. I wondered if the IC were to blame, but haven't anything of the right pinout. Can anyone recommend an equivalent of the CA324E which has +-12V supply capability, with VCC on pin 4 and -VCC on pin 11? I'll put the opamp IC on a breadboard when I find it and see if it or any of the opamps are fritzed.
Circuit diagram is at the end of the attached PDF.
Circuit diagram is at the end of the attached PDF.