Gas welder not working

[Keeler]

Just as the title says. Ive got an older miller gas welder. It used to work great, but then one day, i pull it out to to some welding. I fire it up, strike an arc, let up to adjust it down a hair, then go to strike an arc, and i didnt do anything. Wont to crap, wont even run my grider, its like the generator quit on it. Any ideas???

[slamdvw]

*might* check the output rectifier stage. a quick dirty... possibly hazardous way to do this without disassembling everything is at night, with as little light as possible, look in the vent holes near the BIG amp control knob. Rotate the knob. If you see a lightning storm, you've got shorted rectifiers. ( if possible do it with the machine idling minimize the current ). A buddy of mine had a miller aead200le that did almost that. it would strike an arc, but a 9volt battery had more fury.

Another way, if you're not afraid to take the covers off,... take an ohm meter (preferably one with diode capabilities) to the rectifier diodes. They should conduct only in one direction. Might have to disconnect the wired lead to get an accurate reading.

Last but not least... I'd check brushes. Again, same aead200le ALSO had bad brushes... made quite a lightning show while running.

Does the machine have an outlet on it marked 115v 100hz ( or something to that effect? ) check voltage coming out of it... Voltage there, and nothing coming out the 'business end' of the machine would tell me either brushes or shorted rectifiers.

One more thing *may* help... rotate the fine adjust knob, from min to max ( can be adjusted all day long under load, just changes field excitation ) there will be *some* change in engine RPM... but if it seems to change load considerably,... check diodes.

I do know the dangers of rotating the amp switch under load... ( it melts copper, been there, done that...) but a quick touch with a file and it's good as new.

Hope this helps..

Robert

[oldmiller]

lol keeler. me and you are in the same boat i have the same problem. my miller big 40 wont do nothing it wont arc or the 120v plugin wont work. its got me :confused: :confused: