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Lincoln SAM 400 Problem

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  • Lincoln SAM 400 Problem

    I just got a project SAM-400 that arrived this weekend that I'm trying to get sorted out. A pretty neat machine, and gives me a chance to study some on DC generators. I've read through a bunch of posts, but haven't gotten it figured out yet.

    It does weld, but the output is much lower than the coarse dial either the high or low range. It has to be set over 300 to run a 5/32 7018. The engine runs fine, and idler works correctly. It produces 115 volt AC to the aux outlets. I did have one set of main brushes which were stuck in the holders and arcing, so I went through and freed them all up. It wouldn't weld at all until I fixed that. The commutator is fairly smooth and clean, but could maybe use a little attention.

    I get about 30volt OCV at the output terminals with the engine at high speed. Moving the variable volt control this will change about 2 volts. Switching the machine to CV the voltage can be changed from 26-16volts. The owners manual mentions checking the field voltage, but doesn't have a wiring digram and the machine has been painted making wire colors difficult to figure out. I've got my supplier checking on a service manual for me, but I am trying to figure it out while I'm waiting.

    One thing that this doesn't have is the remote (portable field control), but it does have a jumper across the terminals for the remote, so no resistance at all. It won't do much of anything with jumper disconnected. The manual doesn't give much info on the remote other than its a potentiometer and which terminals to hook up. I think this may be my problem, but haven't been able to find any info to buy and wire a replacement. Am I totally lost? Any other directions or guidance you guys can give will be greatly appreciated, as the suspense is killing me. I really want to go throw a big carbon in this thing and do some gouging.

    Thanks in advance, Brian

  • #2
    A little more electrical information from playing on yesterday. OCV was now up to 42. With an amp clamp and the leads shorted with the coarse control maxed I saw around 500 amps. When welding this dropped to around 200, but it was hard to watch and weld. Welding with a 5/32" 7018 the machine dial had to be set around 400, and I couldn't gouge with 1/4" carbons.

    Digging through a bunch of online Lincoln manuals for accessories I finally found the size of the potentiometer for the remote (10k). I'm going to get one and try that soon. If that doesn't work I'm not sure where to go.


    • #3
      There are a couple of guys on Ask Andy that have those machines.


      • #4
        The jumper doesn't work as well as the PFC. I could never get full output from the jumper.
        Also, make sure that your high idle is at or a little over 1800rpm
        Last edited by J Hall; 07-31-2007, 09:42 PM.


        • #5
          I dont think there is anything wrong with your machine . The SAMs have a "portable field control" that must be hooked up

          If it is removed then you will only get 40-50OCV in CC. You can do two things

          Buy a 5K pot ( not 10K as you assumed....most other Lincoln pots are 10K ) at put the wiper ( center ) on #76 an one of the remaining on #75 on the terminal strip . The terminal strip is under a panel on the front if you havent already found it. You have a 50/50 chance to get the 75 correct. If you choose the "wrong" end of the pot the dial will be backwards ( turn it clockwise will reduce output ).

          2nd option is put a jumper between 75 and 77 and this will fix your problem . I suspect you have the jumper between 75 and 76 which would be incorrect ( thats where the remote goes )

          OCV in CC should be about 90V. In CV its only 50 max

          BTW I hope you realise that you have the Cadillac of welders there. Pure generator goodness with all the bells and wistles. They quite making them a few years ago because they were insanely expensive ( about $18,000 ! ) You could buy a SAE400 for $5K less


          • #6
            Thanks for the tip on the jumper. I will try that tomorrow night. You are correct and it was jumped from 75 to 76. I also appreciate the info on the 5K potentiometer. I will order one soon briefly tried a pot I stole from a meter to see if it made a difference, but it wasn't the right size. It was a 15k that I adjusted to 10k, which wasn't right anyway. Adjusting that pot would would make a barely perceptible change to both the OCV and exciter voltage. I'll let everyone know if that gets me running tomorrow. Thanks again,

            Yes, I did recognize the benefits of the machine when I bid on it. I did not realize they were that expensive. Once I get it going good it will get a good cleaning, and a quality repaint although it isn't that rough now, just not gray. It is definitely not something for small jobs though.
            Thanks, Brian


            • #7
              They were the Cadillac of welding machines. Check the gages, pegged a 500 amp meter.


              • #8
                The jumper from 75 to 77 has definitely improved things. Now I'm up to 62 OCV at the leads. Only 30 more to go. Welding is almost at the right amperage range now. I did check my field coils and came up with 10 ohms per the manual, so they should be all right. Lincoln Electric has been helpful and given me a wiring diagram and pointed me to a newer manual that has a better trouble shooting guide. I think I have some diodes to test now. I intend to match J Hall's meter picture soon.


                • #9
                  For a little closure, I decided to add a picture from today. With the help from here and some assistance from Lincoln I finally got it performing as it should. The picture shows two amp clamps, one 600 amp pegged, and the 1000 amp reading about 700. I'm satisfied now.

                  My problems ended up being: The jumper on the wrong terminals, one of the main brushes stuck in it's holder, variable voltage pot was bad, and high idle was too low. After fixing that and adjusting the PC board pots correctly it seems to do fine. Luckily, I didn't have to buy any major parts.

                  Thanks again for your help.
                  Last edited by blhctd; 02-10-2008, 04:55 PM. Reason: spelling


                  • #10
                    The old SAM-400 was a real nice machine to have around. I'm glad you got yours going!


                    • #11

                      my welder doesnt weld it generates electricity. but no welding the feild coils read 10 ohms the volt meter reads 3v with the welder at full idle .