Newbie needs help with Miller Roughneck 2E. - Page 2
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  1. #26
    Join Date
    Jul 2019
    Location
    Austin, Texas
    Posts
    28

    Re: Newbie needs help with Miller Roughneck 2E.

    New capacitor checks out.

    New diode bridge rectifier checks out.

    Fuse is not blown.

    Leads #25 and #26 show continuity through the brushes, slip rings and rotating field. The whole shmear. And yes, the wires were disconnected from the rest of the machjne for testing.

    I don't know where to go from here.

    Continuity through the selector switch (S1) checks out.

    Oh, and I do get maybe 1 volt out of the power outlets.

  2. #27
    Join Date
    Mar 2015
    Location
    Milwaukee, WI
    Posts
    306

    Re: Newbie needs help with Miller Roughneck 2E.

    Pull back one of the brushes so it does make contact with the ring. Can you measure any voltage between the wires to the brushes with the engine running? You need voltage (and current) going to the rotor to make the magnet field. If there is no voltage to the wires feeding the brushes to the rings, then you need to work back along the circuit and find the cause.

  3. #28
    Join Date
    Jul 2019
    Location
    Austin, Texas
    Posts
    28

    Re: Newbie needs help with Miller Roughneck 2E.

    Quote Originally Posted by Denis G View Post
    Pull back one of the brushes so it does make contact with the ring. Can you measure any voltage between the wires to the brushes with the engine running? You need voltage (and current) going to the rotor to make the magnet field. If there is no voltage to the wires feeding the brushes to the rings, then you need to work back along the circuit and find the cause.
    Thanks, Denis.

    Did you mean to say 'Pull back one of the brushes so it does [not] make contact with the ring.'?

    I pulled the two brush wires off the rectifier, and I get ~18 ohms through the whole works including the brushes, rings and rotor.

    I have not tried to measure voltage across wire #25 and #26 while the engine is running, but I will get that done in the AM.

    Thanks again, man.

    I'm beginning to think I'm going crazy, and I don't have far to go!





    Oh, and do you have any opinion on this?:

    Technical notes of interest to Marine Engineers
    Flashing a generator
    Authored by: ?
    Brought to you by www.dieselduck.net, comments to webmaster@dieselduck.net



    How to "flash" a generator when output is lost due to loss of excitation

    Residual magnetism in the generator exciter field allows the generator to build up voltage during start-up. This magnetism is sometimes lost due to shelf time or improper operation, among other reasons. Restoring this residual magnetism is possible and is sometimes referred to as "flashing the exciter field".

    To restore the small amount of residual magnetism necessary to begin voltage buildup, connect a 12 volt battery to the exciter field while the generator is at rest, as follows:

    Remove exciter field leads F+ and F- from the voltage regulator. CAUTION: Failure to remove the field leads from the regulator during flashing procedures may destroy the regulator.
    Measure the exciter field resistance from the F+ to the F- lead. You should be able to read some resistance as you are measuring a continuous winding. An infinite resistance reading would indicate an open in the exciter field. Also check to be sure there is no path to ground.
    Connect F+ to the positive pole of the battery.
    Hold the F- lead by the insulated portion of the lead wire, touch F- to the negative pole of the battery for about 5 to 10 seconds, then remove.
    Reconnect F+ and F- to the regulator. Repeat the procedure if the generator fails to build voltage.

  4. #29
    Join Date
    Mar 2015
    Location
    Milwaukee, WI
    Posts
    306

    Re: Newbie needs help with Miller Roughneck 2E.

    Pulling back might help you see if there is excitation voltage. If you measure with the brushes in place, the voltage might be a bit lower (harder to see) especially with the chance of a high resistance bad connection. Also check the rotor poles with a small steel wire or nail for evidence of residual magnetism.
    Last edited by Denis G; 08-29-2019 at 10:34 AM.
    Thermal Arc 300GTSW

  5. #30
    Join Date
    Jul 2019
    Location
    Austin, Texas
    Posts
    28

    Re: Newbie needs help with Miller Roughneck 2E.

    yes!!!

  6. #31
    Join Date
    Jul 2019
    Location
    Austin, Texas
    Posts
    28

    Re: Newbie needs help with Miller Roughneck 2E.

    Quote Originally Posted by Denis G View Post
    Pulling back might help you see if there is excitation voltage. If you measure with the brushes in place, the voltage might be a bit lower (harder to see) especially with the chance of a high resistance bad connection. Also check the rotor poles with a small steel wire or nail for evidence of residual magnetism.
    Hey, man!

    I am SO STOKED!!!

    I used the 12 VDC battery to excite the coil, and BAM!!


    I gots me a welder!!!!!

    THANKS!

  7. #32
    Join Date
    Mar 2015
    Location
    Milwaukee, WI
    Posts
    306

    Re: Newbie needs help with Miller Roughneck 2E.

    Quote Originally Posted by johnnybanzai View Post
    Hey, man!

    I am SO STOKED!!!

    I used the 12 VDC battery to excite the coil, and BAM!!


    I gots me a welder!!!!!

    THANKS!
    You said you were close to fixing it. Congratulations!

  8. #33
    Join Date
    Jul 2012
    Posts
    702

    Re: Newbie needs help with Miller Roughneck 2E.

    That's a great feeling, you fixed it. This is how Success feels like.

  9. #34
    Join Date
    Jul 2019
    Location
    Austin, Texas
    Posts
    28

    Re: Newbie needs help with Miller Roughneck 2E.

    [QUOTE=johnnybanzai;8714597]OK.
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    I separated the engine from the generator so I could get at the slip ring assembly.
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    I peeled back the insulation and exposed the connection between the winding and the slip ring. It was broken off.

    It was making contact intermittently.

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    Quote Originally Posted by Denis G View Post
    You said you were close to fixing it. Congratulations!
    Continued . . .

  10. #35
    Join Date
    Jul 2019
    Location
    Austin, Texas
    Posts
    28

    Re: Newbie needs help with Miller Roughneck 2E.

    Sorry for the delay.

    The pic above shows the broken-off terminal from half of the winding. Also the face of the slip ring, where I exposed it with a 2 1/2" air cut-off wheel.

    In the center of the cut, you should be able to make out the hole the rest of that pin broke off in.

    I came within a hair of breaking a drill off in there, but managed not to do it.

    I figured that hole needed to go all the way through, for the ease of manufacture, so, in hopes of confirming that as fact, I drilled the pilot hole for the set screw in line with the much-hoped-for through-hole for that broken pin.Name:  IMG_1437.jpg
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  11. #36
    Join Date
    Jul 2019
    Location
    Austin, Texas
    Posts
    28

    Re: Newbie needs help with Miller Roughneck 2E.

    So I got the set screw in, and dug away at the resin until I uncovered the hole.

    YES!

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    That meant that I could zip off the end of an old, worn out drill bit, and force the pin on through the hole.


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    Last edited by johnnybanzai; 09-13-2019 at 06:41 PM.

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