Another thread about Parweld inverter welder repairs that might be helpful:
In post #24 it mentions a suggestion taken from a Selco welder repair manual that recommends using a low-voltage current-limited DC supply from a bench power supply instead of the 325v DC rectified from the AC mains. This would be done after replacing valuable IGBTs to confirm that the gate drive circuits are working correctly. The outputs from the bridge rectifier(s) are disconnected from the inverter power switching section and replaced with the lab supply. Faulty, floating, or incorrectly-phased gate drivers will cause the supply ( e.g. 30 or 40 volts, limited to 1 or 2 Amps ) to trip, rather than blow the IGBTs.
Another option is to test initially with small cheap IGBTs ( e.g. TO-220 or TO-247, rather than large "power modules" with screw-terminals ). It would not be possible to actually weld, but you could use a 'scope to verify the gate pulses.
Even the old trick of powering-up via a 240v 100Watt filament bulb might be enough to avoid the release of magic smoke...
WWS200, Parweld XTS162 welder repairs
Hi Chaps, I recently bought a known faulty WWS200 MMA/lift rig welder. It doesn’t look as if it has even struck an arc as it is immaculate condition. The issue is that when plugged in the welder is completely dead. I only got it this afternoon so have only had chance to take a quick look...
www.mig-welding.co.uk
Another option is to test initially with small cheap IGBTs ( e.g. TO-220 or TO-247, rather than large "power modules" with screw-terminals ). It would not be possible to actually weld, but you could use a 'scope to verify the gate pulses.
Even the old trick of powering-up via a 240v 100Watt filament bulb might be enough to avoid the release of magic smoke...
