xmt 304 stick mode problem

[doubledoor]

I have a 2007 xmt 304 that had a help 7. After digging into it found the front igbt and diode to be toast. Everything else checked out ok. All the resistors and caps were good.Ordered a new set of miller igbt's and put in a new diode everything works good but stick mode. When I put it in stick mode I get some high number like 980volts and a squealing noise that gets louder and quitter as you turn the amps up and down. running the machine on single phase 220 volt. Please help not sure where to look now?Thanks.

[cruizer]

Well if you lost a Igbt then you lost its protection diode on the side output board as well. Help 7 also means that one of those cap drain resistors is open.

You our didn't check the output board well....

[doubledoor]

Thank you for the quick response. They all ohmed out to what was written on them. But I will check it again. machine welds fine in mig mode. anything else I should check?
Thanks

[doubledoor]

Both r3 and r4 20k resistors ohm out at 18.46k ohms.

[cruizer]

And what do the protection diodes test at, left lower next to the igbt's

[doubledoor]

Dumb question what mode do I test the diodes in? One is new cause I replaced it.

[doubledoor]

On diode mode on my multi meter I got 409 on the front one and 410 on the back one.

[cruizer]

What does the 3phase bridge gate ohm out at. Small Philips head screw and the bolt just above it

[doubledoor]

Sounds like the squealing is coming from the tunnel when it is in stick mode.

[doubledoor]

On 200 ohms it reads 56.1 Ohms. Thats with the board still connected.

[doubledoor]

Anything else I can check?

thanks.

[cruizer]

See, help 7 ALWAYS means a drain resistor on the output board is shot, if left too long then an igbt pops along with its protection diode. your problem now is with the front display board as the machine programming resides there, problem is that this board has zero error codes, yet your still getting a help 7. Help 6 is the top board so that's no the issue.

[doubledoor]

So all the readings I have are good. The drain resistors are good. The diodes are good the gate is good. It's the front board that took out the diode and igbt?

[doubledoor]

Can the front board be repaired?

[cruizer]

So all the readings I have are good. The drain resistors are good. The diodes are good the gate is good. It's the front board that took out the diode and igbt?

No the output board likely got loose, Presto the igbts get hot and pop. The Front board does a lot of stuff and handles the programming. Not going to be repaired and would have to be replaced. The help 7 present is a little odd and is slightly confusing