Miller AEAD 200 LE need help

[Erich83]

Hi all, I'm a new member here. I seem to find my way to this forum pretty regular looking for answers, I usually find them... But I guess I'm stumped here. I'm not a professional welder repair tech, but I've patched several back together.
I purchased an older AEAD a few weeks ago, it wasn't running and the guy really didn't know anything about it except that it wasn't getting any fire. After a few hours of flushing the tank, undoing what had already been done, and cleaning points I had it running. Great! Now on to checking the outputs, only to find that the outputs aren't producing anything even close to anything usable. (AC or DC, 110v or weld current) not even the weld speed 110v outlet. I have cleaned the slip rings, checked brushes, cleaned the tap rings, and more or less brushed every single push on wire connection I can get to. I had it producing 110v until I actually got a HZ meter on it. The Hzs were stupid high, so I backed the governor down to produce my 60 Hz cycle and I've lost the output on the 110 side. What are some of the other things that are common with these problems? And more importantly, how do I know what voltage should be where? I've fumbled through the schematic, but that's not exactly a strong point of mine. if anyone can point me in a decent direction I'd appreciate it.

[Aeronca41]

Welcome! Hope some of us can help you. Please post your serial number so we can look at the right diagrams.

[snoeproe]

I used to have a bluestar 2E. If I remember correctly, 60htz was only obtainable with the weld/power switch in power mode (low rpm) and the fine current dial set to 10 or wide open. If the machine was in high idle or set to weld mode with auto idle off, the unit would be running at near 100 htz.

[Erich83]

Welcome! Hope some of us can help you. Please post your serial number so we can look at the right diagrams.

I guess that would be helpful...
SER # JB527073
thanks.

[Erich83]

I used to have a bluestar 2E. If I remember correctly, 60htz was only obtainable with the weld/power switch in power mode (low rpm) and the fine current dial set to 10 or wide open. If the machine was in high idle or set to weld mode with auto idle off, the unit would be running at near 100 htz.

You are correct. I have a Bluestar 2E that I carry on my old one ton, neither are pretty but serve their purpose in life quite well. So I guess what I'm getting at is, I do understand the ins and outs of how they operate. I just need to figure out what makes them operate. It's probably something stupid that I've overlooked...(I hope)

[Aeronca41]

Perhaps Duane will join in with something obvious; he has a lot of experience with these, I think. I am not a highly experienced welder fixer, but fix all sorts of electrical things, including a number of welders along the way. Is this a manual or electric start machine? When you had power for a while, how high was the frequency?

I've been reading schematics for nearly 60 years, but I have to say I find the schematic diagram in the manual a bit confusing. Maybe I'm missing something, but it shows no AC power outlet that I can find, only DC. Fig. 5-10 on page 10 clearly shows an AC outlet on the panel. There's a documentation issue here somewhere.

Just to be clear, if you put it in POWER mode, low speed, fine current control set to max, I understand you to say you have no voltage at all at the AC power outlet? If that is true, which would imply the exciter circuits are not working, I assume there is also no voltage at the AC weld terminals with the machine in WELD mode and engine speed high? You have already checked that the brushes are moving freely in their holders, so that should not be an issue. How long had this thing been sitting? I wonder if it has lost residual magnetism in the field and needs to be flashed? Have you tried that?

[Erich83]

Aeronca41, It does have voltage. Somewhere around 10-15 volts at power speed, fine tune set to max. It also produces a similar voltage at the AC weld outputs.
I have also checked the rheostat. Which is only getting approx. 9v. Shouldn't that be higher? I would think that would be a solid 12v input to the rheostat to take advantage of the full voltage range. But I am guessing after all. But it does seem like my Bluestar runs at 12v on max setting if I remember correctly.

As to the length of time that it has sat, your guess is as good as mine. If I had to go by the way the gas smelled I'd say it's been sitting for at least 3-5. Possibly longer.
I have heard of reflashing brushless generators, but never one of these, can you elaborate please?

I'll have to get back to you on the frequency. I don't remember off the top of my head. But it was high. And this is an electric start machine.

[Aeronca41]

That should be enough voltage to check the frequency--is it possible you backed off the engine speed too much? I don't know what the voltage should be at the rheostat, but I'll bet Duane does--hope he sees this and joins in. Also, I'm not sure what the numbers should be, but I'd at least measure the resistance of the rotor and stator windings and write it down. You can check the exciter and weld rotor resistance by measuring between the center slip ring and each of the two outer slip rings, one at a time. You will need to pull the brushes away so they don't touch the slip rings while doing these measurements. While you have the brushes pulled away from the slip rings, also measure resistance from each slip ring to the metal shaft of the rotor; should be infinite resistance. (OL on a digital ohmmeter). Making sure you don't have a shorted rotor. Not likely, but possible. Kinda shooting in the dark here.

[duaneb55]

Just seeing this thread for the first time. Several questions to answer thus far and a couple clarifications.

The rheostat of this machine is controlling the ground to the weld side of the rotor whereas the exciter side is fixed. In addition, auxiliary power voltage is controlled by a voltage regulator that has its input voltage transformer connected in the circuit by the WELD/POWER switch in the POWER position. Field voltage to the rotor is in excess of 80VDC if I recall correctly and if flashing diode D4 and RUN/STOP switch are OK you should see at least 12VDC(+) between the center rotor slip ring and chassis ground. This 12VDC just kicks things off each time the machine is started at which point exciter winding output takes over.

Being a 4-pole generator, 60Hz auxiliary power is produced at 1800rpm. The single auxiliary power outlet supplies 115VDC at WELD speed of 3000rpm.

To prevent over frequency output to any devices connected to the duplex or other receptacles at WELD speed, the WELD/POWER switch opens the stator output circuits to terminal strip 1T posts A and B thus preventing voltage at the receptacles.

A couple common component failures are the field voltage bridge rectifier SR2 or corroded tap strap on field voltage trim resistors R2 and R4. A failed SR2 or failed tap strap connection at R4 will prevent any exciter voltage to the rotor and thus prevent proper WELD or POWER output. The WELD/POWER switch has also been known to fail creating output issues.


Rather than go thru a dozen different cause scenarios, PM me an email address and I'll send you the troubleshooting information for your machine so you can systematically determine the cause(s).

[Erich83]

I had a chance to check a few things tonight. It seems as though the SR2 rectifier may be my main problem.
I checked D4, switch on, engine off and I had 12 volts on both sides of the diode, and 12 volts to the center slip ring. With the engine running I got a reading of 12 volts on the switched side and 16 volts from the SR2 side. With SR2 exciter leads unhooked I get a reading of 32+ volts AC. But only 16 volts DC out of rectifier SR2. Should I expect to see a drop in voltage that much? I was under the impression that diodes just cancel the AC wave to give a direct polarity. Or act as a check valve, so to speak. Would that division of the AC cycle also cut the voltage in half? I didn't think it did, but I've been wrong before.
I ohmed the exciter feild (unhooked of coarse) with a reading of 1.6 ohms with no readings to ground. I also ohmed the the armeture with the brushes removed as well. I don't remember the reading, but nothing was going to ground.
I also checked the tap rings for continuity. They seemed to be working/ connecting per my meter. (Reading from wire to wire and wire to resistor in both directions.)

duanneb55, I was checking the the rheostat with the switch on, engine off. This allowed voltage to back feed through the armature and give me a false voltage reading I suppose. Thanks for your help thus far. I at least know (sort of) what order things should happen in.
Any more input is very much welcomed.

[Erich83]

Just thought I’d give an update. I tested the bridge rectifier and it did not test good in all directions every time. I checked it multiple times and it did test good once, but after the initial check it would not test good again. (Could have been me) So I splurged a whole $5 and bought two off of eBay. The old connectors were glued or soldered on and did not come off willingly. After more or less destroying those, I soldered on some new ends, bolted on the new rectifier, hooked everything up and bam! I have outputs. The AC side (110v) is still a little high on frequency but I should be able to get that lined out in the next evening or two. Hopefully it welds!
I want to give a big thanks to everyone that replied.

[Aeronca41]

Sounds like the absolutely right kind of price for success! Good work!