Looking for diodes for montgomery ward welder

[Samshine]

Brent thinks for helping me to understand the voltage better.
Could you please point out the diode with the 250amp. 600volts?
The one i was looking at on e-bay has a rating of 1600 volts.
Thanks, samshine

 

[Samshine]

I think i am catching on now. tell me if i am wrong?
I need the four diodes with part number Semikron SKR 130/6
which is sold by Semikron who advertised the diode Semikron part number. SKR 130/16 on e-bay which has a item number 350238374298
thanks, samshine

 

[patrick_g]

Thanks for the help.
I called tech surrport of the welder, number century gave me. He said all the information he had is that i have four diodes. And they are 150 amps. each.
Question is?
Can i just upgrade two of the diodes or do i have to upgrade all four diodes at the same time?
Thanks again for your help. Hope to hear from you soon.

All because of weak link in the chain.

 

[Steve Bosshard]

Semikron SKR 130/6

SEMIKRON - IGBT, Diode, Thyristor, Power Semiconductor Modules, Chips, Assemblies

Now we are getting somewhere.

This may be a generic cross NTE Cross Reference

or Tiny URL - NTE Cross Reference

Sounds like you are on the road to recovery. I would use the OEM part unless there was a substantial reason not to.

Now, wonder what made the diodes fail to begin with ? Just time ? Shorted something? power spike while welding ? Fan quit cooling ? Covered with dust / thrash blocking airflow ?

Sure don't want to let the smoke out of the new diodes.

steve



steve

 

[Transit]

Sam, this is the one you want, This Diode on ebay
Semikron SKR 130/16 250A 1600V Rectifier Diode DO-8 - eBay (item 350238374298 end time Feb-06-10 04:47:44 PST)
As for the 300 amps? NO! components connected in series have a common current with the voltage of each element added. One 150 amp diode or ten connected in series = 150 amps.

 

[oldmech]

Hi! Ac-Dc 250 amps welder can work with 150 amps on DC so I think if you put 300 amps diodes ,You can burnt the transformer supply a lot more expensive than diodes. My small Lincolh welder use 40 amps diodes for 70-80 amps dc. I change or burnt two diodes in four years. I replace it $40 each. No necessary to change all. I test the diode with VTVM. Good luck Oldmech

 

[BrentD]

Brent thinks for helping me to understand the voltage better.
Could you please point out the diode with the 250amp. 600volts?
The one i was looking at on e-bay has a rating of 1600 volts.
Thanks, samshine

My bad... I missed the 1 in the 1600 and saw it as 600. So the 1600V diode is even better. With 2 in series they can withstand a reverse surge of around 3200V. That should be way more than adequate for a welder. Those diodes will probably outlive all of us.

 

[Samshine]

I want to change all four of the diodes. I want to go the right way out, along with the cheapest way out in case if something else is wrong with the welder.
I want feel do bad if i have to junk it.
The diode that is on e-bay. If i decide to go this way, should i get two diodes like this?
Semikron SKR 130/16 250A 1600V Rectifier Diode DO-8 - eBay (item 350238374298 end time Feb-06-10 04:47:44 PST)
And two like?
Semikron SKN 130/16 250A 1600V Rectifier Diode DO-8.
Other words two SKR and two SKN diodes with the same rating.
Thanks again for all your help. samshine

 

[BrentD]

I want to change all four of the diodes. I want to go the right way out, along with the cheapest way out in case if something else is wrong with the welder.
I want feel do bad if i have to junk it.
The diode that is on e-bay. If i decide to go this way, should i get two diodes like this?
Semikron SKR 130/16 250A 1600V Rectifier Diode DO-8 - eBay (item 350238374298 end time Feb-06-10 04:47:44 PST)
And two like?
Semikron SKN 130/16 250A 1600V Rectifier Diode DO-8.
Other words two SKR and two SKN diodes with the same rating.
Thanks again for all your help. samshine

This depends on how your welder is wired. The welder should have 2 metal plates, each with two diodes mounted to it. What you are looking for is how the wires going to the positive and negative lead jacks are connected. If the positive wire is connected to one plate, and the negative wire connected to the other plate, then yes, you would need 2 SKR's and 2 SKN's. If, however, one jack is connected to a heat sink plate and the other to the diode pigtails then you would need 4 identical diodes. If that is the case then which lead is connected to the plate would determine which type you would need. (If the positive lead is connected to the plate and the negative to the pigtails, then you'd need SKR's, but if the negative was connected to the plate and the positive to the pigtails then you'd need SKN's.)

If, neither welding lead is connected to a plate but rather the main transformer is connected to the plates and the welding leads are connected to the pigtails, then you definitely need two of each type, but would have one of each type on both plates and the pigtails of the two common types from each of the two plates would be tied together and go to one welding lead, while the other two pigtails would be connected together and go to the other lead.

In any case you could get by with using 4 identical diodes of either type, but that would require changing some wiring around inside the welder.

 

[Samshine]

I know there is two diodes bolted both ends to the same heat sink. (I assume these are negative diodes). Diodes running east and west.
While the other two diodes are bolted to the other heat sink with a plate running from one of the welding connecting jacks connecting the two pig tails on a stud which the stud is bolted to the same heat sink. Diodes are running north and south.
I hope you can tell by my description, which type of diodes i need.
Thanks for all the help. samshine