Miller Bluestar 2E AC/DC help!

[Vogte53]

Picked up my first generator unit yesterday as I need something for projects and some pipe fence building. The Craigslist selection wasn't great but I found this Bluestar and even though it wasn't welding as is I picked it up knowing that it was a little bit of a risk. It did run but only with the choke on. The guy told me it needed brushes to he replaced them but hadn't put them on because of the carb issue. Just for kicks I put the brushes back on. I could not find a diagram so I places one wire on each brush.


I am assuming the prong the wire is placed on is irrelevant?? I got enough power to make some sparks but it would not establish as arc.
I also noticed the wires to the throttle solenoid were cut. The solenoid tested okay with 12v put to it but I need to get the engine running right to even test the output on the wires that are supposed to control the solenoid. I assume the first step is to rebuild the carb.
Any advice is appreciated.
SN: JG068586

[Vogte53]

[duaneb55]

Based on the SN you posted, here's the manual http://www.millerwelds.com/om/o424b_mil.pdf for your machine with the wiring diagram on page 20.

With the unit off and ignition switch in the run position you should have battery voltage between the two brushes. If not, check for a failed open flashing diode D8 that is located in the harness between the engine and generator (wires #1 and #4 if I'm not mistaken).

They're not too bad but you could also clean up the slip rings with some 320grit sandpaper.

If you have battery voltage at the brushes, start the unit and see if this voltage increases to something above 170VDC. If DC voltage at the brushes doesn't increase above battery voltage with the unit running, check for a bad WELD/POWER switch or open(s) in the field voltage bridge rectifier SR1.

You can use the manual wiring diagram and parts break-down to help identify these components if/as needed.

[snoeproe]

I have the DC only bluestar 2e. It is a very nice welder. Welds great. Only complaint I have is the tecumpseh 16hp motor is a bit loud.
The motor is the tecumpseh OH 160 model. Carb is a Walbro LMH. You can buy a rebuild kit for the carb on eBay. Your motor is not getting enough fuel if you have to run it with the choke on. Carb will require a thorough cleaning first, then check and verify your float height is correct. Then try running it again.

[Vogte53]

Thanks for the help. I ordered the carb kit yesterday. I also found that the throttle solenoid is getting power.with the engine off I am getting battery voltage at the brushes but when running it does not seem to jump to 170v. Ill look into it some more today.

[snoeproe]

You may not necessarily need the rebuild kit for your carb but for the price of it, it doesn't hurt. When I got my bluestar 2e welder, the carb was over flowing a bit of gas. It ran ok but the motor would backfire when it idled down when welding. My issue was my float height in the carb. With the carb bowl off and the carb upside down, the float should be sitting parallel with the carb body base. If it's not, bend the small tab that controls the inlet needle. Adjust that tab till the float is sitting parallel with the carb body base. Once my float height was set correctly, the overflowing of fuel stopped and the motor idled down smoothly with no backfiring.
Once I had those issues resolved, I replaced the spark plug, air filter, installed a fuel filter and changed the oil.

[Vogte53]

Okay I've got it torn apart right now. Ill be sure to get it set right. I have another question, this time about the battery. My welder did not come with one. I have been using the lawn mower batter (275 cold cranking amps) to start it and it doesn't do a great job. How many CCA would you recommend I look for when I buy one?

[snoeproe]

It states in the manual what they suggest you use for a battery. I've honestly been using a marine battery from my boat on mine. It's much larger than a lawn mower battery. It does a good job of cranking over the 16hp tecumpseh. There are much better batteries out there today than they had back in the 80's.

[Vogte53]

Thanks for all the help. Cleaned up the carb and picked up a battery today (360 CCA) and I think it do just fine. I temporarily mounted the machine to my homemade trailer I threw together mostly out of stuff I picked up for free. Since the welder didn't come with a battery box I mounted the battery in the toolbox and used the quick connect plug that came on the battery cables. Hopefully the pics are right side up this time.

[snoeproe]

Just had a look at my battery. 650 marine cranking amps. Rolls her over with no hesitation at all.

[Vogte53]

I reinstalled the carb after cleaning it (still don't have the rebuild kit). It runs only slightly better, still needs at least half choke. While it is running though I am still getting very low voltage at all three 115v plugs and only small sparks from the welding leads. The d8 diode snapped in half when I was disconnecting the clips on either end so I will be replacing that but I'm not sure that is my problem. My weld/power switch is controlling the solenoid but could it still be the problem? If so how do I test it? I also am unsure of what you (Duane) meant by checking for opens on the SR1 rectifier. I apologize for my lack of electrical troubleshooting skills.

[duaneb55]

What did you clean the carb with? If you didn't use a chemical soak type carburetor cleaner you likely still have blocked fuel/air passages in the carburetor body sections.

Diode D8 is known as the flashing diode which provides battery voltage to the (+) brush for initial rotor excitation to start the generating output process. As you originally had 12VDC at the brushes, it was functioning as it should and you'll have to replace it in order to continue troubleshooting.

The WELD/POWER switch is a 4-pole switch and is performing three different duties only one of which is controlling battery voltage to the throttle solenoid. Another is disconnecting the auxiliary power outlets from the generator output to prevent highly excessive voltage from being connected to any device plugged into the unit in WELD mode. The third is connecting the correct exciter output windings in WELD and POWER modes to the field circuit bridge rectifier SR1 to provide the correct field voltage in the selected mode.

It is the third function you need to check the switch operation for. To do so, you should have continuity between the center terminal wire #2 and side terminal #12 in WELD and #2 and #13 in power.



Here are a couple links to testing a bridge rectifier. The wincogen.com is a written procedure using a multimeter that doesn't have a diode test function and the youtube link is using a meter with a diode test function. Although the youtube sample bridge rectifier is of a different configuration than that of the one in your welder, their function and test procedure is the same.

http://www.wincogen.com/files/downlo...er_testing.pdf





As for your question regarding which wire goes where at the brushes, if you have them backwards your weld output polarity will be opposite what your selector switch indicates.

[Vogte53]

Thanks a ton for the great help. I'm fairly certain the rectifier is shorting because I am getting reading when contacting between the + and AC on even when I reverse the leads on the multimeter. The corrosion on the terminals makes getting quality ready a little difficult. Im also having a tough time finding a new rectifier (and switch) online.
http://weldmart.com/MILLER%20POWER%2...PAGE%20MST.htm
Is "D" the part I need?

[snoeproe]

When you cleaned the carb did you remove the inlet needle and blow air through all passages?

[duaneb55]

Thanks a ton for the great help. I'm fairly certain the rectifier is shorting because I am getting reading when contacting between the + and AC on even when I reverse the leads on the multimeter. The corrosion on the terminals makes getting quality ready a little difficult. Im also having a tough time finding a new rectifier (and switch) online.
http://weldmart.com/MILLER%20POWER%2...PAGE%20MST.htm
Is "D" the part I need?

Yup. That's what you're looking for.

[Vogte53]

I soaked the carb today and blew air through all of the passages. The fuel hose barb had some bad build up inside that I rimed with some naval jelly. After reassembling it will run on WELD with no choke but still needs about 1/3 choke in POWER.

[duaneb55]

Sounds like the low speed/idle circuit might still have an issue. What did you soak it in?

[Vogte53]

I just soaked in diesel and blew it out with aerosol carb cleaner and compressed air. You think some chem-dip would do much better job? Even though it runs at higher rpm I can still tell that there is an issue.

[Vogte53]

The one problem I had while cleaning the carb was the main jet. I tried to remove it but it seemed like I was going to do more damage than good so I left it in and cleaned it the best I could. I just now saw a YT video with someone saying that the main jet on that carb is never supposed to be removed or adjusted as it could case issues.

[duaneb55]

I just soaked in diesel and blew it out with aerosol carb cleaner and compressed air.

That won't normally do it. Can't cut thru the varnish and corrosion.

You think some chem-dip would do much better job?

Guarantee it. Likely won't have to worry about that main jet you can't get out either if you do.

[snoeproe]

Sounds like it's getting better. How does the spark plug look?

[Vogte53]

The plug looks good. Wasn't bad when I got it but cleaned it anyway and it's been fine.

[Vogte53]

I guess I will get some chem dip and try to find a rectifier tomorrow. I replaced the D8 diode I broke btw and I'm back to about 18v at the aux. power plugs.

[snoeproe]

I usually use brake/contact clean spray for cleaning carbs. Is your fuel tank full of old gas? Some fresh gas with a little sea foam in it will help the carb some what once you get it running correctly. Does yours have a fuel filter on it?

[Vogte53]

Drained all of the old gas when I got it and yes it does have a fuel filter. The fuel hose seems a little bit questionable to me though. It's transparent blue. I might just pick some better stuff up if I go in to town today.