When you measured the DC voltage at the torch tip with respect to the work clamp ( 17.5v to 33v ), I guess the torch polarity was already shown on your voltmeter as positive.... Unless someone had specifically modified the machine for fluxcore, I think it was and is normal polarity.
Any careless attempt to do the swap risks the capacitors going "pop" big-time! They are polarised, and so torch polarity must be changed after the capacitors, not at the rectifier.
I suppose the capacitors are 8,000 uF each ( not 80,000 ). Gently charging a cap with a few volts and checking if it holds that voltage for a while is a pretty good test. However, use a low-current source ( 9-volt PP3 battery, or 4 x 1.5v AA cells in series ), rather than the infinite Amps from a 12v car battery!
Returning to my suggestion in Post #6 that voltage is getting lost due to a high-resistance joint in the high-current secondary path: if you measure the torch tip voltage under load and then compare that with the open-circuit voltage, you may see a drop, and can then go backwards down the circuit path to see if it is being lost at a specific point. The problem is doing this whilst welding is not easy, you need a steady load. A few 60W car headlamp bulbs ( in series ) can be used, but that is only a 5-Amp load. For a higher current load, if you have not got one of these:
www.westermans.com
you can Google "hillbilly load bank" for an alternative.
Any careless attempt to do the swap risks the capacitors going "pop" big-time! They are polarised, and so torch polarity must be changed after the capacitors, not at the rectifier.
I suppose the capacitors are 8,000 uF each ( not 80,000 ). Gently charging a cap with a few volts and checking if it holds that voltage for a while is a pretty good test. However, use a low-current source ( 9-volt PP3 battery, or 4 x 1.5v AA cells in series ), rather than the infinite Amps from a 12v car battery!
Returning to my suggestion in Post #6 that voltage is getting lost due to a high-resistance joint in the high-current secondary path: if you measure the torch tip voltage under load and then compare that with the open-circuit voltage, you may see a drop, and can then go backwards down the circuit path to see if it is being lost at a specific point. The problem is doing this whilst welding is not easy, you need a steady load. A few 60W car headlamp bulbs ( in series ) can be used, but that is only a 5-Amp load. For a higher current load, if you have not got one of these:
Kemppi 400 amp load bank
For Sale - Used Kemppi 400 amp load bank . Available Today | Worldwide Delivery
www.westermans.com
