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Spinning rectifier and diode help?


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  #1  
Old 09-18-2013, 04:13:48 PM
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Default Spinning rectifier and diode help?

Ok; I know this is not an Onan unit but I need information / help.
I have a 20Kw New Age / Stamford UCI-224C13L Gen end hooked to a Kubota V2203-EGB motor.
My two questions are; how is the diode & rectifier held into place on the shaft?
My unit was exposed to the salt air and all the threaded shafts that the diode leads attach to are rusted and corroded, can they be removed and replaced without having to purchase a new $450.00 unit?
Thanks in advance,
Jim
Ps my 15.0RDJC has been a real trooper this year, got to run it three times this year without issues, thanks to all the help from this board!
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Old 09-18-2013, 05:38:42 PM
Jim Rankin Jim Rankin is offline
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Default Re: Spinning rectifier and diode help?

Going to have to see pictures of that, can't wrap my brain around the concept of threaded shafts holding a rectifier on the rotor. Many times the larger diodes used to make a bridge rectifier are stud mounted into positive and negative heat sinks.
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Old 09-18-2013, 06:06:56 PM
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Default Re: Spinning rectifier and diode help?

Hope this helps explain what I need...
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Old 09-18-2013, 08:04:48 PM
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Default Re: Spinning rectifier and diode help?

Like Jim said.

Diodes have a threaded stud that screws into the aluminum plate. Use heat transfer paste when mounting new ones.

3 of the diodes will be positively biased and the other 3 negative. All 3 on each plate are the same.
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Old 09-18-2013, 10:09:11 PM
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Default Re: Spinning rectifier and diode help?

Quote:
Originally Posted by Gunny View Post
Diodes have a threaded stud that screws into the aluminum plate. Use heat transfer paste when mounting new ones.
3 of the diodes will be positively biased and the other 3 negative. All 3 on each plate are the same.
Gunny / Jim Thanks,
I guess my question is not clear.
How does the rectifier stay in place? Does it fit into the recessed area or is it screwed down some how?
If I remove it, can I replace the rusted / corroded parts and reinstall it?

The diodes and their leads appear to be OK I just don't want start to remove the leads and break off the post that the nut attaches to that holds down the lead with the terminal on it.
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Old 09-18-2013, 10:22:48 PM
len k len k is online now
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Default Re: Spinning rectifier and diode help?

For removing nuts , first thing I'ld do is wire wheel all the rust off exposed threaded stud, otherwise the nut will bind on rust and snap the stud. Wire wheel on air die grinder or dremell.

Can try penatrating oil couple times a day for a week. But on cars I like to heat nut to expand them, but that would likely kill the diode it you get it much hotter than something over 180 deg F. So maybe warm nut then quickly freeze spray the stud to shrink stud, be ready to turn quickly , temps will equalize fast. Use heat sheilds if using torch..... heat plume can burn up stuff behind nut.

I assumed you are talking about removeing wire lead from top of diode. (one in air).

Most diodes are threaded into heat sink, on cars some diodes are pressed in. The threaded ones will have a bolt hex pattern on them that you can put a standard socket over (might have to use a deepwell socket)

~~~~~~~~~~~~~~~
Heres a picture of a stud diode, this one has a solder terminal on top instead of your top stud and nut. But I think you'll get the idea.
http://www.surplussales.com/Semicond.../Diodes-3.html
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Old 09-19-2013, 07:42:45 AM
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Default Re: Spinning rectifier and diode help?

I would like to know how to take out the whole rectifier with the diodes as a complete unit. Is it held down by adhesive or is there some other type of attachments, like does it just sit / slide into a cup like device on the shaft?

Thanks for all your help so far.
Jim
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Old 09-19-2013, 10:08:05 AM
Jim Rankin Jim Rankin is offline
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Default Re: Spinning rectifier and diode help?

Sorry, not having been into one of those, I cannot tell you. Maybe someone else will come along, or you may be able to figure it out for yourself. I can say with some confidence that at least one, if not both, of the heatsinks will be insulated from the shaft somehow.

If it were my project, I would tend to let it alone unless I had to get it loose. A little corrosion on the surface of the aluminum isn't going to hurt anything as long as the diodes and field wires are still making good connection.

The diodes used are a package I am not used to seeing, however it appears they simply have a stud on each end instead of the solder lead I am used to seeing on the end opposite the stud base (whatever that would be called)
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Old 09-19-2013, 03:22:16 PM
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Default Re: Spinning rectifier and diode help?

Well now that I have the new $400.00 unit in my hands, I now see how it is anchored to the shaft.

If you compare the photos you can see why I want to replace it!

Thanks for you efforts!

Jim
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Old 12-03-2013, 12:15:06 PM
serkan90 serkan90 is offline
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Default Re: Spinning rectifier and diode help?

@Skytruck. Yes, it’s quite obvious why you wanted to replace them. In the pictures in the above post, it seems they have corroded way too much. Did you use them more than their normal life expectancy? Now that you have got a new unit which has cost you a lot, I’d advise giving it some sort of protection from the salty water or this unit might go down as well. In case you somehow had gotten to know how the diodes were fitted in their place you might not have been able to place them reliably. The contributors to this thread have explained a lot for anyone who reads this thread though.
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