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Thread: Power Mig 255 PC Board

  1. #1
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    Power Mig 255 PC Board

    I bought a broken Power Mig 255 last night. It was cheap and has a new gun on it so I figured it was worth the gamble.

    When plugged in, the transformer hums but it doesn't do anything else.
    I've done a little testing with a multi-meter to rule out the basic stuff, although that's not something I'm great at.

    The welder was at a Lincoln repair facility and they told the previous owner that the PC board is bad. The weird thing is, someone put a PowerMig 255C board in this welder. The board is dated August of 2017. The guy I bought the welder from said it did function with this board in it as one point, however he didn't seem to have 100% confidence when he said that. Comparing the wiring diagram between the G3521-1 (correct 255 board) and the G4824-3G1 (255C board currently in machine), they appear to be very similar.
    Unlike the correct board, the 255C board is potted with clear epoxy in a back plastic case. I'm tempted to cut it out so I can inspect the back side of the board for burned up traces.

    I'm thinking the best course of action is to do a little more diagnosis of basic parts and then just order the correct board.
    Does that sound like the best approach?

    And my second question, does anyone have a parts Power Mig 255 that they'd sell me the board from? I'd hate to buy a brand new board and instantly fry it if something else is wrong with this welder.

  2. #2
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    Re: Power Mig 255 PC Board

    First what is the code number of the welder, with that we can see if you have a 255 or a 255C then we will know which pcb is the correct one.
    the 255c pcb cost a lot more than the 255 pcb.
    Find the diagram in the welder. Find the main transformer try to measure the voltage on all the secondary coils. then find the D2 diode and test it. make sure it is not open or shorted. other things to look at are the gas valve and make sure it is not open or shorted. don't have either in the shop right now so not sure what the difference is.
    But you can call Lincoln tech support and ask them. and if the 255c pcb could have worked in your welder and could it have damaged anything.
    As long as you ask good questions and show you have the knowledge to safely test the welder they will work with to find figure out what else might be bad and if when you buy the right pcb will it get damaged. They will not help with PCB repairs so don't ask. they will cut you off.
    You can go to lincoln web site and under the support tab find the parts button.
    open it and select the guest tab. this will take you to the service navigator.
    enter you code number and it will take you to the correct parts list for your machine and a lot of other information. parts order and pricing is disabled.

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  4. #3
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    Re: Power Mig 255 PC Board

    Appreciate the suggestions! I'll check those parts today.
    This is the first time I've ever torn into a welder. It's a good learning experience and I look forward to welding with this thing eventually (hopefully).

    The code is 10990. The G3521-1 part number I listed is the one Lincoln calls for. I talked to Lincoln tech support yesterday and ran the scenario by the guy. He suggested putting in the correct board, didn't have much input about the 255C board being able to operate the welder or if it could have damaged anything.

    I tested the D1 diode last night and believe it is bad. I get the same value with the multi-meter leads in either direction, so the diode is open, right? It's on a large aluminum heat sink and some of the other connections on that heat sink look a little crispy, like they got hot or arced out at one point.
    A friend of mine sent me a pretty detailed Lincoln troubleshooting guide for this specific machine so I'm going to follow that today.

  5. #4
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    Re: Power Mig 255 PC Board

    Quote Originally Posted by Shwoody View Post
    Appreciate the suggestions! I'll check those parts today.
    This is the first time I've ever torn into a welder. It's a good learning experience and I look forward to welding with this thing eventually (hopefully).

    The code is 10990. The G3521-1 part number I listed is the one Lincoln calls for. I talked to Lincoln tech support yesterday and ran the scenario by the guy. He suggested putting in the correct board, didn't have much input about the 255C board being able to operate the welder or if it could have damaged anything.

    I tested the D1 diode last night and believe it is bad. I get the same value with the multi-meter leads in either direction, so the diode is open, right? It's on a large aluminum heat sink and some of the other connections on that heat sink look a little crispy, like they got hot or arced out at one point.
    A friend of mine sent me a pretty detailed Lincoln troubleshooting guide for this specific machine so I'm going to follow that today.
    Depends on what that same value is. Testing in the circuit may not be accurate but if it is open(infinity)in both directions then it would have to be bad.

    If it was reading zero or close (shorted) in both directions ? It could be good and test that way if it is in the circuit still.
    Last edited by danielplace; 11-14-2020 at 02:50 PM.

  6. #5
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    Re: Power Mig 255 PC Board

    Well I'm gonna have to throw in the towel on this one unfortunately
    Looks like someone removed the snubber board and did some wire rerouting. I'd imagine that's a pretty critical component, right? A new snubber board is $110, plus the time of having to undo someone's wiring job, plus the cost of a new $700 PC board. Just not worth it for a 17 year old welder that may have other issues for all I know.

  7. #6
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    Re: Power Mig 255 PC Board

    It looks like the Power Mig 255C doesn't use a snubber board. I can only assume someone had that 255C board lying around so they decided to do some adapting. Can't see any other reason to replace the correct board with a more expensive one.
    I may still fool around with this thing.

  8. #7
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    Re: Power Mig 255 PC Board

    post a picture of what you think is the D1 diode.
    D1 diode is about 1 inch square block with 4 connections. It is a bridge diode assembly with 4 diodes. only 2 are used. An ohmmeter may read OL both directions.
    will depend on the meter and what range you selected. Diode test mode is best.
    If you measure the right two wires it will read a short circuit. Because you are reading the transformer coil.
    Set down with the diagram and colored pencils. Trace out each circuit and mark up your diagram showing circuit is still there and correct or missing or changed.
    Then if you decide to spend the money on the pcbs and repair it. You will be ready to correct the changes in the wiring. Might have to buy some plugs and sockets. if harness is missing or damaged. Can be purchased from Lincoln or an electronic supply house. If you can find someone local that has one and will let you take covers off and compare will save a lot of time figuring what is missing or changed.

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  10. #8
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    Re: Power Mig 255 PC Board

    Shwoody,

    Thanks for buying that. I looked for it the next morning, and it was gone. Hard to resist at that price.

    Have you checked the companies that rebuild welder boards?

    Innovatcorp.com shows $470 to repair the board I looked up. It is a G2803-1. When I searched for the mainboard that's the number that came up several times. Some of the companies may have inventory of the board you need.

    I hope you get it working.

    Steve

  11. #9
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    Re: Power Mig 255 PC Board

    Quote Originally Posted by ccawgc View Post
    post a picture of what you think is the D1 diode.
    D1 diode is about 1 inch square block with 4 connections. It is a bridge diode assembly with 4 diodes. only 2 are used. An ohmmeter may read OL both directions.
    will depend on the meter and what range you selected. Diode test mode is best.
    If you measure the right two wires it will read a short circuit. Because you are reading the transformer coil.
    Set down with the diagram and colored pencils. Trace out each circuit and mark up your diagram showing circuit is still there and correct or missing or changed.
    Then if you decide to spend the money on the pcbs and repair it. You will be ready to correct the changes in the wiring. Might have to buy some plugs and sockets. if harness is missing or damaged. Can be purchased from Lincoln or an electronic supply house. If you can find someone local that has one and will let you take covers off and compare will save a lot of time figuring what is missing or changed.
    I was mistaken about that smaller diode testing bad, I had been using a cheapo multi-meter. Went and bought a better meter and the diode tested fine. The one I was testing is the smaller one that sits on the heat sink. Haven't tested 4 terminal one that you're talking about yet.
    I'll do some wire sorting this weekend like you suggested.

    Quote Originally Posted by Steve007 View Post
    Shwoody,

    Thanks for buying that. I looked for it the next morning, and it was gone. Hard to resist at that price.

    Have you checked the companies that rebuild welder boards?

    Innovatcorp.com shows $470 to repair the board I looked up. It is a G2803-1. When I searched for the mainboard that's the number that came up several times. Some of the companies may have inventory of the board you need.

    I hope you get it working.

    Steve
    I was surprised no one else bought it! Definitely a fair price.
    Unfortunately I don't think anyone will repair this 255C board since it's epoxy potted. The correct one is not, which is nice.
    That G2803-1 board you came up with must be for a different code, or maybe the 3 phase unit. The code on this welder calls for G3521-1.
    The welder was at the General Air repair facility up in Commerce City. Their records just show "board is bad" and that the customer opted to not have it repaired.

    It's a bit of a predicament. I could buy the correct PC board, wire a snubber board back in and redo wiring, or stick with the adapting someone else did. I'll just have to do some more testing this weekend and see if I can find a faulty component that could have caused the board to go bad.
    If I give up on it, I'd probably sell it to you for what I paid, if you have any interest.

  12. #10
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    Re: Power Mig 255 PC Board

    Innovat has the G3521-1 listed for $330.

    Steve

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