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Need advice on testing a used 1990 Dialarc 250 AC/DC, no High-Frequency

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  • Aeronca41
    replied
    Understand. I think his problem was a bad contactor? Not a big deal to replace. Last time I replaced one (in a commercial air conditioning system, which was very similar or identical to those in welders) I think it cost me $58 or $68. You don't have to buy contactors from welder companies; you go to the local electrical supply house and buy what is called a "definite purpose contactor" with the appropriate number of poles, contact current/voltage rating, and coil voltage. Same with switches if you are careful to get the correct ratings. May have to mess with lugs on cables, mounting, etc, to get a generic to fit, so it's worth considering the factory original if the price is close and it's still available.

    Other failures? Any welder could have diodes fail, just like any car could get a flat tire, but they are more reliable than moving parts like contactors, fans, and switches. Even transformers can fail, but most just go on forever (unless the fan fails, you continue to weld, and they burn up). Of course, if they do, the welder is junk unless you can find a donor machine. The Dialarc is made of very low failure rate parts, with very simple circuitry, so is super reliable. Probably more parts in a square inch or two of a modern welder circuit board than in the whole Dialarc.

    Anxious to hear about the vintage model 61. That is just cool! (Speaking of transformers just going on forever...)

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  • Stefen7
    replied
    Once again Aeronca41, I thank you for your input. Dialarcs are known as reliable, but as Tarry99's problem last week shows, there can be issues that are difficult to troubleshoot. Those are the ones I am searching through past threads looking for so I have a heads up.

    As an aside, I made an offer on the Model 61M and am waiting for the seller to reply. I'm hoping to save it from the scrap pile.

    Leave a comment:


  • Aeronca41
    replied
    No responses from Dialarc users; will try to help. Never used a Dialarc but looking at the schematic there is not a lot to go wrong. The Range switch contacts could be worn or burned, I'd look at the current adjust rheostat for damage or overheating, and as you mentioned, other internal signs of damage or overheating. Check the welding cable receptacles on the front-if they got loose somewhere along the line, or the cables weren't plugged in tightly, they could be damaged from overheating. Make sure the fan runs, and power input jumper connections are correct for the input voltage being used. As long as the transformer and mag amp (the other thing that looks like a transformer) are OK, pretty much everything else seems like it would be an easy fix if required. If it welds OK, I'm guessing it's probably OK. Hope it works out for you. I think you can count on it being heavy and a bit power hungry. :-)

    Perhaps someone one with more direct Dialarc experience will have some other input.

    Leave a comment:


  • Need advice on testing a used 1990 Dialarc 250 AC/DC, no High-Frequency

    I am not familiar with the Dialarc units and need advice on testing one before buying.

    I have the manual, (OM-314K = JK674521). Welder is plugged in, and can be tested.
    It was used in a shop, it is now owned by a hobbyist, stored in a garage.
    I will use it for stick welding on things like attachments for my skid-steer, ¼ inch plate and larger.
    It will be occasional use, not daily use in a welding shop.

    I have some 6013 electrodes:
    1/8” = 80 – 130 amps; Dialarc low range = 35 – 155 amps
    5/32” = 150 – 190 amps; Dialarc high range = 90 – 265 amps

    After the basics, checking for damage, bad cables, mouse nests, etc.
    If I can burn a rod on AC high & low and DC high & low, is that it? It either works or it does not?
    What are the common maintenance or failure issues with a Dialarc?

    Thank you for your help. Stefen

    Just to clarify the heading, the unit does not have High-Frequency, not that it is broken. When you make a typo in the heading, you cannot edit, changing 'no' to 'not.' Oops.
    Last edited by Stefen7; 08-15-2016, 06:56 AM.
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