Long time lurker, first time poster. This forum has helped me diagnose several issues over the years, but finally have one that has me stumped and need some assistance. The owners manual from Miller doesn't provide me with enough information to diagnose and my search has brought up different potential issues; although none were quite the same as what I'm experiencing.
Background: I picked up a Miller AEAD-200LE about 6 years ago to use around the house on various projects; most of the time it sits in the garage awaiting the next welding project or power outage. Serial Number JD702043, approximately 1984 vintage. When I first got it, it ran rough and I bypassed the original fuel pump with a 12v unit wired into the ignition system. The engine has ran perfectly and welded beautifully after that; never had an issue with the idle switch or ability to draw a bead with 6011, 6013 or 7018 rod.
We've had a few long term power outages the past year or two, so after reading through the manual, I did the 240V plug swap per sections 4-3 and 4-4 so I could tie it into the house transfer switch and run the well pump if necessary. After doing the plug swap, everything still ran fine until this past week. Unit has sat in a heated garage for about 4 months since the last run / weld.
Pulled the unit out and set it for welding, with the auto idle switch activated. Immediately upon striking or scratching the rod, the unit will increase engine speed from low to high / welding (3000 RPM) and stay there. Can't draw a bead or maintain an arc and it won't return to idle until I manually switch from weld to power mode, then it'll drop down to 1800 rpm and lope along. Tried swapping leads with a spare set, as well as different electrodes; no change.
Used a Fluke 77 multimeter to test the output voltages of the AC & DC weld terminals, as well as the power outlet(s).
In weld mode, I get the following readings:
AC plugs - 12.15V AC, DC plugs - 5.65V DC, 109VAC in accessory plug, 17VAC at the 240V plug (measured hot to neutral)
In power mode, I get the following:
AC plugs - 7.18V AC, DC plugs - 4.82V DC, 109VAC in accessory plug, 142VAC at the 240V plug (measured hot to hot, should be ~240), 71VAC at the 240 plug (hot to neutral, should be ~120).
I've tried to "re-excite" the system by increasing the RPM while in weld mode, no change in the above readings. Also pulled the side cover and looked at the brushes and connections. No obvious signs of corrosion on the connections (pulled each individually and cleaned just in case), no signs of burnt components or traces on either board. Have yet to scratch through the board coatings to get to the components for detailed testing.
Based on the readings at the 240V plug, I'm leaning towards a winding going out. However, based on the threads I've read so far, components on the PC1 board could be bad leading to erratic readings.
I believe my next step is to pull the boards out and start chasing the traces & components, but figured I'd check with others first to see if there's something else I should check first.
Thanks in advance.
Background: I picked up a Miller AEAD-200LE about 6 years ago to use around the house on various projects; most of the time it sits in the garage awaiting the next welding project or power outage. Serial Number JD702043, approximately 1984 vintage. When I first got it, it ran rough and I bypassed the original fuel pump with a 12v unit wired into the ignition system. The engine has ran perfectly and welded beautifully after that; never had an issue with the idle switch or ability to draw a bead with 6011, 6013 or 7018 rod.
We've had a few long term power outages the past year or two, so after reading through the manual, I did the 240V plug swap per sections 4-3 and 4-4 so I could tie it into the house transfer switch and run the well pump if necessary. After doing the plug swap, everything still ran fine until this past week. Unit has sat in a heated garage for about 4 months since the last run / weld.
Pulled the unit out and set it for welding, with the auto idle switch activated. Immediately upon striking or scratching the rod, the unit will increase engine speed from low to high / welding (3000 RPM) and stay there. Can't draw a bead or maintain an arc and it won't return to idle until I manually switch from weld to power mode, then it'll drop down to 1800 rpm and lope along. Tried swapping leads with a spare set, as well as different electrodes; no change.
Used a Fluke 77 multimeter to test the output voltages of the AC & DC weld terminals, as well as the power outlet(s).
In weld mode, I get the following readings:
AC plugs - 12.15V AC, DC plugs - 5.65V DC, 109VAC in accessory plug, 17VAC at the 240V plug (measured hot to neutral)
In power mode, I get the following:
AC plugs - 7.18V AC, DC plugs - 4.82V DC, 109VAC in accessory plug, 142VAC at the 240V plug (measured hot to hot, should be ~240), 71VAC at the 240 plug (hot to neutral, should be ~120).
I've tried to "re-excite" the system by increasing the RPM while in weld mode, no change in the above readings. Also pulled the side cover and looked at the brushes and connections. No obvious signs of corrosion on the connections (pulled each individually and cleaned just in case), no signs of burnt components or traces on either board. Have yet to scratch through the board coatings to get to the components for detailed testing.
Based on the readings at the 240V plug, I'm leaning towards a winding going out. However, based on the threads I've read so far, components on the PC1 board could be bad leading to erratic readings.
I believe my next step is to pull the boards out and start chasing the traces & components, but figured I'd check with others first to see if there's something else I should check first.
Thanks in advance.
