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Blue Star 2E won't start arc

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  • rsl1963
    started a topic Blue Star 2E won't start arc

    Blue Star 2E won't start arc

    I bought an old Blue Star 2E and have managed to get it up and running. I tested the AC plug and it worked fine. When I tried to weld it would only spark slightly at the rod tip but would not start. I pulled the sides off and found the fuseable link going to the capacitor was fried. I had the capacitor checked and it passed the first test but failed subsequent test so this appears to be my problem as I checked voltage to the connections and there was voltage. Does anyone know of a replacement for this that does not cost $378 which the miller repair shop quoted me? The manual states that it is a 20 uf 500 volts DC capacitor.

  • Aeronca41
    replied
    Thinking about this a bit more, I think I would go with a plastic film capacitor for this application rather than an electrolytic--it's the closest to the oil/paper that was there originally. I have not been home enough to spend a lot of time searching, but I am not finding any 20 mfd 500 v film caps so far. If you get some time, look in the Mouser/Allied/TEDSS/Digi-Key, etc. catalogs on line and see if you can find any before I do. You can always parallel two 10 mfd to get 20, (or four, 5 mfd) and the voltage rating can be anything 500v or higher. Sometimes you hit some great prices at TEDSS. You are probably not going find one in a metal can, but that's OK--a can is not essential.

    I'm also still on the motor run (NOT motor start) capacitor thought train. Good quality run caps are film caps, and should work just fine, I think, but I can't find any data to back that up--just an old guy's gut feeling. You would definitely NOT want to use a motor start capacitor because those are only designed to work for a few seconds at a time, not constantly as in this application. They would be dead very quickly.

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  • Aeronca41
    replied
    Having a really hard time locating the right capacitor. I would love to know if a non-polarized motor run capacitor would work in this application but can't find any info on that one way or another. Based on their internal construction, they should actually be pretty close to the cap that was there in the first place--they are not electrolytics in the classical sense of the word. I will try calling a manufacturer's engineering support line tomorrow and see if they can provide some into. Will try again tomorrow.
    Last edited by Aeronca41; 03-27-2019, 09:21 PM.

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  • Aeronca41
    replied
    Great. Will try to get back to you when I get home this evening.

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  • rsl1963
    replied
    That sounds like it would work, I would appreciate the information on the electrolytic cap and you were right about the wire rather than fuseable link. I took a better look at it and it appears to be a burnt wire under some tape which had a burn spot on it. I checked out the link above which is just under 200 American but by the time I convert it to Canadian and add import fees it comes out to over $300 so I like the cap idea. Also if you could explain how to check the bridge rectifier I would appreciate it.

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  • Chrisheavymech
    replied
    https://www.millerserviceparts.com/e...-20-uf-500-vdc

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  • Aeronca41
    replied
    Well, that is indeed a "special" capacitor; looked all over the internet, and spoke with an electrical motor supply house guy that I have a lot of confidence in. (BTW, the guy there was speechless when I told him how much the shop wanted for the cap.) Can't find anything exactly like it. If it were my welder, I think I would get the best aluminum electrolytic cap I could find, make a new mounting strap, and put it in, being very careful to connect + to + and - to -.

    I am a bit troubled by your reference to a fusible link. I am not a welder expert, but have 50+ years experience in Systems Engineering and untold hours sitting at benches fixing busted electrical and electronic stuff. In my limited welder fixing experience, I have never run across a fusible link; I'm afraid what you thought was a fusible link was just a wire that got burned up by a short circuit somewhere, especially since the parts list makes no reference to a fusible link. Perhaps one of the techs here can enlighten me if I'm wrong; I'd really like to know, and one thing you learn in 50 years dealing with this stuff is there is always something new to learn.

    If you want to try the "non-standard" approach of just putting in a quality electrolytic cap, I can see if I can find one that looks appropriate. Let me know; it will take a little time to research available caps and their temperature and ripple specs. I love to see these old machines brought back to life--maybe just because I'm old......

    I would also check out the bridge rectifier SR1 while youre working on it. Can be done with just the ohmmeter function of a digital multimeter. If you need instructions on how to check it, let me know.

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  • rsl1963
    replied
    Thank you for your response. I was surprised by the amount that the shop wanted as well, but I do live in Canada where prices are much higher. The serial number from my welder is HK258996. I will post a picture of the capacitor but there are no numbers on it, I am going by the description in the parts manual. I tried looking online for a suitable replacement but I am a millwright so my understanding of electrical issues is lacking. I would also need to replace the fuseable link but I find no mention of it in the manual. I would love to get this machine up and running to help me with several projects and to have a mobile rig would be awesome.Click image for larger version

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  • Aeronca41
    replied
    Please post your serial number. Unless that is some sort of super duper capacitor with special characteristics, that seems pretty high. Try the Miller part number from your manual at Miller4less.com and see if it's any cheaper. Can you post a pic of the writing on the side of the cap so we can see if it has any special characteristics? Have to go to the cap mfgr web site and decode the numbers, but it should be possible to identify the specifics. Should be able to find a suitable replacement at Mouser, Digi-Key, Allied, Newark, etc. for hundreds less. I'm guessing under a hundred bucks--maybe far under, depending on specs. I'd be hoping for $20-30.

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