miller syncrowave problem

[squazy84]

i have a miller syncrowave 275s tig welder and ive noticed the foot pedal amperage control getting lazy and un responsive and kind of on off at times making it difficult to regulate the amperage nicely on aluminum, I believe it may have started after our very damp winter of last as i recall there being a problem with no hf start but after I scratch started it a few times it seemed to sort itself out, any help or info on probable causes bearing in mind im not an electronics expert but have no problems having a go and can keep my tongue away from the sparky bits

 

[squazy84]

suppose i better start by checking the resistance of the foot pedal with a multimeter and see if its a consistant ramp

 

[shenion]

Most likely the rheostat in the footpedal has gotten corroded. Some contact cleaner should get it going.

 

[NotANormalCoder]

If Shenion's idea doesn't help, check the wiring. Biggest problem I see regularly is wires breaking inside the cable - normally at the footpedal end just by the strain relief, where it gets most stressed. Sometimes at the plug to the machine (less likely). Carefully release strain relief, then pull one wire at a time. If ones gives, there's your problem. Ensure all wires are numbered/coloured, then cut them all back to before the break and rewire.
HTH Dave

 

[squazy84]

well the foot pedal is less than a year old but it could very well be corroaded, i will get on to this soon as possible cheers!