Kemppi Pro Mig 4000/Inox

[austingtir]

I see from old posts theres a few people hopefully clued up on these old pulse mig machines by kemppi.

I actually have two of them im trying to diagnose now. (Im not an expert in electronics!) The pro Inox machine is acting like its down a phase or two and the fans dont work and the pro mig 500/4000 I have in pieces in front of me now had no current output at all. Both machines the display and power lights work and it displays data on the display the wire feeder feeds wire on the pro mig 500 when you pullt he gun trigger put no current.

So on the pro mig 500 I started by repairing the 3 phase filter board. The white RIFA caps were all cracked and the machine would trip the breaker after about a minute after it was turned on (replacing all the caps on that filter board seems to of cured that issue. I can see power making its way down to the secondary elements.

Nothing is jumping out at me other than the mains filter board I already fixed.....

Since dismantling the secondary I have tested:
The rectifier g004. = Tests good with multimeter
Primary rectifier vg101 = Tests good with multimeter

All the components on the large z001 board which has like 28 capacitors on it little grey rectangle pulse caps and 4 blue rectangle rifas then 3 very large arcotronics MKP 1.44/A 75UF 700v. Everything on that board seems to test ok EXCEPT the large arcotronics caps..... Im not even sure how to test them TBH I put multimeter on them and get no capacitance reading they seem to be discharged now when I initially put multimeter on them it said something like 25volts initially not sure. I initially thought all these caps had leaked their guts out but not sure if its varnish spray or leakage? As said all the little caps test ok just the arcotronics im not sure about.

 

[austingtir]

So im now looking at the diode card and the high speed diode packages mounted to the big heatsink in the middle of the three items above as pictured below:

 

[austingtir]

So im now looking at the diode card and the high speed diode packages mounted to the big heatsink in the middle of the three items above as pictured below:


"What kemppi calls diode cards two units diodes are all specially matched by kemppi or some such I tried measuring components on this board I get nothing from the blue rifa capacitors resistors looks fine the blue varistors (one card gets 68k ohms probing one direction and 8 mega ohms probing the other so that ones consistent........ the other card gets 0.37 mega/ 70.8 k ohms and 13/10 mega ohms so that one differs a bit). I tried testing the 3 leg heatsink mounted transistor looking things (diodes?) cant get consistent readings out of any of them. Thinking maybe I should try with aligator clips? Or do they have to be demounted??

"Ultra fast soft recovery diodes apt2x30d100j x2 of those mounted as pictured" I cant figure out how to test these. Get nothing probing them with multimeter in either direction.

View attachment 148389

 

[austingtir]

I was wrong about the apt2x30d100j diodes I get 0.361 volts testing black probe bottom left and red probe top left on each unit. Im guessing that means good?

 

[austingtir]

I was wrong about the apt2x30d100j diodes I get 0.361 volts testing black probe bottom left and red probe top left on each unit. Im guessing that means good? It says dual parallel on the description of the unit online? does that mean theres two diodes in each unit?? but I dont quite get how they are connected inside I havent seen a internal circuit layout in my searching yet......