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Thread: xmt304 help 7

  1. #1
    Join Date
    Jan 2011
    Location
    Clover, SC
    Posts
    14

    Default xmt304 help 7

    Happy New Year Everyone!

    I recently purchased a used xmt 304 cc/cv unit (1999) and a 60 series wire feeder with some other equipment for a decent price. I knew the unit had the error code when I bought it. It is a 1999 model 230/460v unit. It is very clean inside and out, figured it was worth repairing as I hear these are good machines.
    When powered up I hear the contactor pull in then a another click then the machine will set for around 15 sec or longer then go into a Help7. the display shows current setting but voltage says .1 or.3 in stick mode. All resistors on side board check good. 20k resistors do get warm. When I took the bolts out of the caps and checked across terminals with an ohmmeter I got just under 20k. When I took the board off It was apparent that some one had been messing with the IGBTs (mitsubishi). But they checked good. I checked them according to a October 24 -25 2008 thread. As far as the diodes... if I use an ohmmeter what should they read? Any help or guidance is greatly appreciated.

  2. #2
    Join Date
    Dec 2010
    Location
    near wilmington nc.
    Posts
    17

    Default

    i know a guy here in wilm nc. that specializes in welder repair. if u need a number let me know...

  3. #3
    Join Date
    Jan 2011
    Location
    Clover, SC
    Posts
    14

    Default

    Thanks. I will keep it in mind.

  4. #4
    Join Date
    Mar 2010
    Location
    Ceres, California
    Posts
    358

    Default

    this is what is listed in the service book.
    Help 7 Display
    Indicates that the input voltage is too high and
    the unit has automatically shut down. Operation
    will continue when the voltage is within
    the acceptable upper range limit (15% above
    the applicable input voltage). Effective with
    KK104771, Help 7 can also indicate a bus
    voltage imbalance (see Section7-9).
    Failed Diode (D1 or D2) on PC2.
    Failed HD1 pulling down +15VDC supply on
    PC1 (unplug hall device to verify).
    Failed IGBT pulling down +15VDC supply on
    PC1 (unplug firing leads RC5 to verify).
    PC2-PLG2 incorrectly inserted into
    PC1-TP1.
    Also to test diodes you need a multimeter that has diode test mode or an old analog meter.
    Be extra careful when powering this units with the cover off. stay to the front and ware a face shield and heavy coat. They can blow up. Remember there is around 325 volts on each of the large caps. These are fatal voltages if you get into them wrong.
    Glenn 300 amp stick
    Millermatic 35
    L-tec plasma

  5. #5
    Join Date
    Jan 2011
    Location
    Clover, SC
    Posts
    14

    Default

    Thanks for the info. Will check. Yesterday, I was looking at it and decided to try out the machine on lift arc tig and did not get an error although I did not try striking an arc. Diodes d1 and d2 are reading the same. Checked with DVM in diode mode What and where is the HAL? I did notice that the fan does not come on at all when powered up. Is this normal? With most other machines I have seen or used the fan comes on when powered up then shuts off and comes on when needed if the machine has a "fan on demand" setup. How warm or hot should the 20k resistors get? To me they seem to be on the borderline of being hot not warm.

  6. #6
    Join Date
    Mar 2008
    Location
    Dallas,Tx
    Posts
    172

    Default Xmt

    The 20K bleeder resistors do get quite warm. Assuming you are running the machine on 240 vac, you should get the same voltage on each of the large blue caps, about 340 vdc as I recall. The clicks and delays you describe are normal and you should see a slight jump in cap voltage as you hear the second small click from the top board, pc1, and the caps go up the the final 340 vdc or so. My guess is you have a problem in pc1 or the display board, pc3. The Hall device is the current sensor mounted on the left output terminal and is connected to the pc1 on your machine with a shielded cable and a small white 4 pin connector. We can check any of the devices mentioned here if you like and the boards can be repaired. PM anytime.
    BTW, ccawg is giving you good advice about precautions. The caps are holding a very large amount of energy and if one fails under power, it can provide an experience you will not soon forget. weldersales

  7. #7
    Join Date
    Jan 2011
    Location
    Clover, SC
    Posts
    14

    Default

    Will check the voltage on caps and the list of things that ccawgc mentioned. Yes I am aware of the safety aspects. I keep as far away as I can when powering it up. Your guidance is greatly appreciated.

  8. #8
    Join Date
    Oct 2004
    Location
    Edmonton, Alberta
    Posts
    7,741

    Default

    99% of the time Help 7 has to do with the side output board, generally with the bleeder resistors, and/or with the left side igbt. It might test fine, though if you remove the output board, that igbt, may have the base blown off it.

    Will want to verify the protection diodes on the board itself.

    Thi board is rather expensive, though very easy to repair.

  9. #9
    Join Date
    Jan 2011
    Location
    Clover, SC
    Posts
    14

    Default

    Quote Originally Posted by cruizer View Post
    99% of the time Help 7 has to do with the side output board, generally with the bleeder resistors, and/or with the left side igbt. It might test fine, though if you remove the output board, that igbt, may have the base blown off it.

    Will want to verify the protection diodes on the board itself.

    Thi board is rather expensive, though very easy to repair.
    All resistors on the side board checked good. When I had the board off, the igbt did not show any visible signs of damage. I did only take of the igbt that is closest to the rear of the machine.
    Both of the caps have 340v. If I unplug the HAl the open circuit voltage goes up from .3 to 5.3 in stick mode. In lift arc mode, no errors until i try and strike an arc.

  10. #10
    Join Date
    Oct 2004
    Location
    Edmonton, Alberta
    Posts
    7,741

    Default

    When you say someone was messing with the igbts, in what way? Doesn't sound to me that that first one is turning on. They are supposed to be PRX CM100DY-12H.

    It may be that someone changed the igbt to a non Miller version but didn't fix the driver board for it. Does it look like the protection diode had been changed?

    Small black unit on the output board with 2 prongs to the left of the igbt mounts.

    Best to replace the IGBT's with the actual Miller parts. Need the serial# to find out the correct part#'s.

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