300A diode questions

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.





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


I am having a hard time finding these parts.

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


Thanks,
Gif

 

Google partminer,they show the part no-there Is a regional office near me,
also they have other offices check it out monday.

 

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.

 

Look at NTE6354/55.
Here is a list of distributors who supposedly have stock.

I found these by Googling 300 amp rectifier.

 

thanks,

I found this too:

http://www.alliedelec.com/Images/Products/Datasheets/BM/VISHAY_SEMICONDUCTOR_ITALIANA/503-0165.PDF

 

and this:
http://www.surplussales.com/Capacitors/BathtubCaps.html