Diversion 180 board repair

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Hey all, Haven't posted here in a while, probably since my last attempt at fixing an inverter machine.  I tried valiantly, and failed to fix a Passport Plus with a bad pc1.  i learned a lot in the process, which is what I was hoping to get out of it, along with a portable mig which I didnt get.  Well the new project is a Diversion 180, I bought two dead machines with similar serial #s on ebay. one had bad IGBT modules and diodes, the other has a bad main board. I got the two built in to one and after a few tentative welds it looks like shes gonna hold together!  Now Im getting greedy.  I tore the bad main board down, bad igbts on the board, bad diode on the same heatsink.  Im replacing those as well as the input rectifiers and the driver ICs and optoisolators. there are 6 igbt on the board, 4 are driven by 2 ics, and the other 2 are driven by transistors and all the igbt are the same part#.  So I got parts ordered, but Im nervous i have missed something.  Any input, experiece and especially documentation would be greatly appreciated. If i can get the second machine working I will sell the one with all sano Oem parts in it and by an even bigger reclamation project to take its place.  Here is the machine serial: MF121032LAlso i thought the igbt and the rectifier looked rather cheap compared to what was in the Passport Plus i failed at repairing. that and with the heatsink design and mounting the Diversion machines are definitely not meant to be banged around liked the beefy handles would lead you to believe.


Reply:There are no pcb diagrams published for current miller welders.Plus Miller has clamped down on passing out service manuals.If I give out a manual I could loose my Statis as a miller service shop.Even if I hire a helper, he is not supposed to have access to the service manuals until he completes Miller's online course.
Reply:Thanks for letting me know, corporate America doesn't want us having any fun. Could I get some general info on the low voltage supply on the board? The input rectifiers were ok but all the input igbt were blown so I'm guessing there is some dead stuff on that side as well the input relay solder joints are charred but it looks like someone even less skilled than me was assaulting it with a soldering iron
Reply:Sounds like you lost the pfc boost IGBT and the soft start relay.You also could have bad buss caps. There is a to220 transistor along the edge of the pcb that will test shorted to one of the heat sinks. You are going to have to find a way to test all the parts on the pcb and see which might be bad. may take two or three tries to repair. I am afraid you have had a cascade failure and a lot of parts may be dead or damaged.
Reply:Q1-4 were shorted, 6-7 were ok, replacing the to220 transistors as well as the drivers u1-2 for q1-4. Forgot the optocouplers oc1-2 on this order. I don't have a good way to test the big caps, I thinky buddy has an ear tester big enough for the job. Nothing looks swollen, no leaks or smells. D56 is a t0220 diodes on the edge of the board,  q5 and q10 are to220 pnp transistors by the big heatsinks, they seem ok but they're setting replaced too. The only relay I see is cr1 which itself looks ok, both the solder joint looked bad as well as having soot on both sides of the board 650ohms coil resistance, not good right?Last edited by jmmorriso; 10-21-2020 at 09:41 PM.Reason: Adding info
Reply:Well got everything in and no dice. No lights, sounds or smoke. Going to keep on the switching power supply side, I'm going to replace the controller ic and the switcher ic (transistor) all the surface mount caps and resistors look good so far. Having a hard time identifying the surface mount caps. Had one that I thought was bad, removed it and found there was a second one in parallel with it throwing off my reading. Want to put a new one on since it got a little crispy. It's a 100uf, not sure what voltage rating or size. Do I measure the pads on the pcb?
Reply:I replaced the second round of components, still no luck. Also, while carefully probing the working board under power I managed to slip and short the dc bus to ground at least I think that's what happened. Big transistors go off like firecrackers! I'm done for the day. Starting to think I'm not cut out for this line of work. I'm still in one piece, and that's a good thing.