I HAVE AN OLDER MILLER BIG 40 RUNS BUT NO WELD OR AC POWER

Check brushes.

try electrozad supply,waffles electric,windsor factory supply,praxair welding supply,liquid air welding supply,future weld supply good luck

not making enough electricity,get it serviced

hi, you have 2 big resistor with ajustable tab on it,check for visual damage on it and rusted connector or tab,
replace tab at same place if you disasemble it

After 18 years, the welder has either lost its residual magnetism (which allows the output voltage to ramp up) or the voltage regulator is defective. Another possibility would be the brushes for the field not contacting the rings like they should - damaged brushes or weak springs. Contact Miller/ Hobart for a service manual, these checks are relatively easy to perform. The manual will give you specs that can be used for go or no go testing.

these need a good power supply , i looked and did not see the duty cycle on this welder if you are doing heavy welding 100% power it will need 30- 40 minutes to cool of to weld again. it all depends on the units duty cycle, stated on the welder spec plate ..can you bypass the auto feed speed mode ? this might be the issue.. good luck ..use all the protection you can when welding these are like the sun and can and will burn exposed skin and eyes .. if'n i was any help throw me a bone and vote thanks jay

Hi Kevin,
Causes of poor penetration: Travel speed too fast, welding current too low,
poor joint design / and or preparation, electrode diameter too large,
wrong type of electrode, excessively long arc length.
Solutions: Decrease travel speed, increase welding current, increase root
opening or decrease rootface, use smaller electrode, use electrode with deeper
penetration characteristics, reduce arc length.

I think you mean you have a Miller Synchrowave 200.

Typically, you would want to use AC below about 250 amps. In this case (to keep it simple), use AC, adjust your balance to about 4, use an 1/8" pure tungsten, pure argon at about 20CFh, and set the panel at 170amps to get things started. For general purpose, use 4043 filler.

Now - these are just generic settings, but they will get you going.

does this unit have a high side and a low side if it does plug it into the low side and try it.

open inspection door,which also the fine tuner knob is ,there's a 2x4 size circut board that snaps out with little force to remove,this is the voltage regulator board,look for 4700 ohm resisitor burnt into,tv tech can fix or order new board at $227.00 what i paid.