Miller 180SD current control problem

[gr8legs]

I've had this 180SD for years and have used it for maybe two hours - so essentially a 'new machine'

Sitting down this week to get back some TIG skills for an upcoming project and it seemed fine until *poof* and the variable current control has died. (No it didn't really 'poof', I just used that as a technical term for illustration

Adjusting the pedal or the range control on the welder I get what appears to be 100% power regardless of setting. 10 Amps, 180 amps, or anywhere in between makes no difference. Makes it tough to weld 0.0625 6063 aluminum with that much power.

Anybody had this problem before or maybe have a service manual with schematics I could beg, borrow or steal?

Very annoying.

Thanks in advance,

Stu

 

[brino]

My first thought is whether the pedal is fully plugged in.

Here's a manual: https://www.millerwelds.com/files/owners-manuals/O360A_MIL.pdf

For the symptom you mention is gives only this in the troubleshooting section:


I'm still going thru it......

-brino

 

[brino]

Do you get any "HLP" messages on the display?

The diagram on page 25 (or 29 of 52 in the pdf) isn't real useful, just how the board is wired up.
Perhaps one of the SCRs (mod1 or mod2) are shorted.....

Does it work on stick (SMAW) mode?

-brino

 

[brino]

Here's someone else with same/similar issue:
https://weldingweb.com/showthread.php?33635-Miller-syncrowave-180-sd-output-problem-please-help!

 

[gr8legs]

Follow up on my welder issue:

I opened it up in preparation for re-soldering every connection on the control board but before taking that step I disconnected, cleaned and re-connected all the connections to the control board.

Fired it up and seems to work OK again. We shall see.

Stu