Miller aerowave not working, amps set to HIGH value and cannot change

[Ignoramus19737]

My coworker has a Miller Aerowave TIG welder. It did work
previously. Now it does not work. The amps display shows a very HIGH
number that cannot be adjusted with amperage knob. It does weld at
that extremely high setting and melts welding rods.

I have some pictures of the welder and board LEDs at:

https://www.machinerymoverschicago.com/blog/Miller-Aerowave-Welder-Problem/

Would anyone suggest a solution? Also does anyone know a good welder
repair shop on the Chicago area? Thanks

[nub12]

Just a stab in the dark.

Is the current set by a potentiometer?

If one end has gone open it could be pulled high or low causing the
welder to think you want full current.


If you're confident of not electrocuting yourself, try to measure the
voltage on the wiper of the potentiometer as you wind it up and down and
see if it sweeps up and down.



I'm not familiar with high end welders and can't believe how much
electronics there are inside that one!

[Leon Fisk]

Might be something related to the foot-switch? Not sure how they work
together with the knob settings...

Have you downloaded the owners manual:

https://www.millerwelds.com/files/owners-manuals/O319H_MIL.pdf

Looks like a nightmare inside without the full tech manual to guide you
around. Much more complicated than the Millermatic I'm trying to
repair...

I see you found the Miller Forum. Nobody has jumped forward to help you
so far but it hasn't been up long. You might get a tech manual from
that site if you ask nicely :)

--
Leon Fisk
Grand Rapids MI/Zone 5b
Remove no.spam for email

[Jesse Bear]

Interesting that there are separate controls for current EN and EP. have you tried both settings? I agree that you want to be looking for an open or short in the control pot or perhaps in the pedal wiring.

If the voltage doesn't change on the pot wiper, try disconnecting the wire from the pot and see if it changes then. If it doesn't, the problem's in the pot (assuming the's voltage getting to the pot and the other side of the pot is grounded (or at least has a different voltage) - the wiper terminal voltage should be able to move the full range between the two ends). If it does, reconnect that wire and disconnect the other end of it. If the pot voltage still can change, the problem is on the board you just disconnected from, and we have to look deeper. Otherwise it's in the wire