Dynasty 200 SD blown capacitor

[MAC702]

Thanks for the follow up!

[Irritantno9]

It’s taken me six years to follow up on this. I have subsequently been reunited with my Aircrafter 330st and 350P.
I finished the pre-power checks and utilized jjohn76’s excellent thread where he shows the semikron pin out:

https://forum.millerwelds.com/forum/welding-discussions/597484-dynasty-200sd-low-buss-voltage#post597484

I tested with a Peak Atlas DCA75. Everything corresponded with his pinout.

I replaced both caps and reassembled.

Welder works well now.Appears problem was bad capacitors. I regret sitting on this for so many years but I was getting tired of looking at it.

Looking forward to reacquainting myself with a square wave machine!

[Irritantno9]

Tests

You get your handy dandy tech manual, and meter out the connections in the pre power section

I did all pre power tests up to 7.7 in the manual. All diodes, igbt and resistors test within range.Any way to test semikron?Any tips on testing bottom side components?I guess those are next.

[cruizer]

You get your handy dandy tech manual, and meter out the connections in the pre power section

[Irritantno9]

Thanks

Any idea on part # and cost?

There is only one SemiKron that I can see. This is the white module that is sandwiched between the horizontal backplane and the heatsink.

Any idea what caused this failure ?

Is there a troubleshooting procedure for testing the SemiKron?

How do I determine the extent of the damage?

[cruizer]

I'd suspect that the Semikron mods are pooched and you've pooched the interconnect board

[Irritantno9]

I posted last year regarding a failed TVS on the 14 pin output on my 200 SD.

it worked fine for many months. It has sat idle for a few weeks until
two weeks ago I needed to weld something and upon power up, the display came up and While I was setting up to weld the display went blank. I cycled power several times and I only heard faint buzzing.

Yesterday I had some free time and pulled the troubleshooting manual out and popped the cover off.
before I began testing I powered it up one last time.

the display lit up and went thought the power up sequence.
I was not expecting that and shortly thereafter one of the two 450V 1500uF capacitors on the top board ruptured and let out its smoke.

I have pulled the main board left the white Semikron module in place. Any suggestions about what to do next. I am suspecting AC has gotten into the caps.