300A diode questions

Discussion in 'General Electronics Chat' started by gif, Oct 31, 2009.

  1. gif

    Thread Starter New Member

    Oct 31, 2009
    3
    0
    Hello,

    Thanks in advance.
    I have used information from this site many times. The knowledge base on this site is awesome.

    On to the issue. I have a large welder that stopped working in the DCSP (DC Standard Polarity). I tracked down the problem to the large diodes on the main bridge rectifier.
    I found 1 shorted and 3 open. I also found a Bath Tub type capacitor popped. See pics.

    The info I have found says the diodes are 300 amp / 250 PRV.
    2 are FWD and 2 are REV.
    [​IMG]
    [​IMG]
    [​IMG]


    The capacitor is 4 MFD / 150 VDC.
    Is this type of capacitor still made? If not what replaced it?
    [​IMG]

    I am having a hard time finding these parts.

    Can anyone point me to a good on line source for parts?


    Thanks,
    Gif
     
  2. loosewire

    AAC Fanatic!

    Apr 25, 2008
    1,584
    435
    Google partminer,they show the part no-there Is a regional office near me,
    also they have other offices check it out monday.
     
  3. Wendy

    Moderator

    Mar 24, 2008
    20,765
    2,536
    Hmmm, I don't know know for sure, but I would think industrial outlets, like Allied Electronics, Grainger, McMaster Carr...

    The last two might have it, but I doubt it only because they don't usually have electronics components. These are odd enough I could be wrong.
     
  4. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Sadly, Acushnet has closed their doors - along with a number of other capacitor manufacturers.

    Have a read here:
    http://www.plasticcapacitors.com/bulletin2.html

    Those rectifier diodes were made in July of 1981; 28 years ago. You just don't see those large rectifiers anymore. They waste too much power as heat.

    Nowadays, they're using things like power MOSFETs with support circuitry as "ideal" diodes for synchronous rectification. It's certainly more complex than just using a rectifier diode, but vastly more efficient in operation.
     
  5. Ron H

    AAC Fanatic!

    Apr 14, 2005
    7,050
    657
  6. gif

    Thread Starter New Member

    Oct 31, 2009
    3
    0
  7. gif

    Thread Starter New Member

    Oct 31, 2009
    3
    0
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