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Onan Magniciter Theory FAQ


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  #31  
Old 07-15-2011, 12:17:04 PM
Ted_Cool Ted_Cool is offline
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Default Re: Magniciter Theory FAQ

Magneciters are extremely rare, and expensive.

You can find Power-Tronics here

830 895 4700
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  #32  
Old 09-07-2011, 07:27:27 PM
loonatickman loonatickman is offline
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Default Re: Magniciter Theory FAQ

pvplas - i've got a 12MDJC-3R/2268R and can't get any voltage from it. If you have any manuals or info that might help in diagnosing this I'd really appreciate a copy. My Exciter is the 06SX1N3B also. It's a great diesel generator and I'd really like to get it working again for the coming winter season. Mike m_olesnevich@vernonsoft.com

Thanks.
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  #33  
Old 08-24-2012, 02:47:41 PM
BergmanJ BergmanJ is offline
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Default Re: Magniciter Theory FAQ

Folks,

I have attached the data sheet for stud-mount power diodes which make a good replacement for the original Onan's.

---------- Post added at 01:47 PM ---------- Previous post was at 01:41 PM ----------

Well -- I thought that I did!

They are Ruttonsha International Rectifier, Ltd. 16FL40 [400V PIV] (or 60 [600V], or 80 [800v]), for one side (two diodes) of the power bridge. 16FLR40's. etc., are "reverse polarity", for the other two diodes of the power bridge.

These are inexpensive, available from Mouser, and a very good replacement (exact stud-mount as original).

Regards, JLB
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  #34  
Old 08-24-2012, 04:39:16 PM
GHanners GHanners is offline
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Default Re: Magniciter Theory FAQ

I tried to buy some mouser tells me 1 is in stock 1 is non stock with min order (i forgot the min order) do you have any of these spare or another source ?
Thanks
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  #35  
Old 08-24-2012, 06:16:40 PM
Jim Rankin Jim Rankin is offline
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Default Re: Magniciter Theory FAQ

yes, always need to check stock with Mouser before you finalize your order. I usually was able to find a higher amperage or higher voltage etc that was instock that would work.

digikey and others should have them. also look on ebay. Usually are some there as well. I have a cache of my own so I don't have to order every time I need one or two.
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  #36  
Old 08-25-2012, 12:06:24 AM
GHanners GHanners is offline
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Default Re: Magniciter Theory FAQ

what is the stock rating for the diodes ?
16a 400v ?
or is that a higher amp/volt to prevent failure ?
the ones you have listed are fast recovery it's only 60hz will std one work ?
16F40 & 16FR40 ?

what about voltage diodes p/n 305-0240 anyoine have a spec on them ?

Thanks

Fire Down could that be on shut down ?
as the rpms go down the hz go down so the voltage should rise to the field ?
or am i missing something

Last edited by GHanners; 08-25-2012 at 12:19:45 AM.
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  #37  
Old 08-25-2012, 12:28:35 AM
Power Power is offline
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Default Re: Magniciter Theory FAQ

I posted this before - did an ebay search and bought stuff off these folks - very reasonable - $2.95 incl. shipping direct from China, which is same place they all come from. I prefer American made, but seems they are all made in China now. On this replacement, Original was 25 amp 400 volts, I upsized a bit.

BRIDGE RECTIFIER -Model: KBPC3510 / 35A 1000V NEW
Seller:
Member id goodbuy711 ( Feedback Score Of 57928)
99.8% Positive feedback

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| Visit store: ALLPARTSPIPE
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  #38  
Old 08-25-2012, 03:08:58 PM
Jim Rankin Jim Rankin is offline
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Default Re: Magniciter Theory FAQ

'Fire down' refers to the point where the magneciter cuts the voltage to the field and it begins to collapse bringing generator terminal voltage down.

It should behave about like pulse width modulation. If the load is low, magneciter send voltage to field, which raises the voltage and it reaches "fire down" which causes the excitation to drop. Then as terminal voltage declines, the magneciter turns back on and you get another pulse which brings the voltage back up. With some resistance and inductance in the circuit, output voltage doesn't bounce around noticably.

Increase load and the voltage takes longer to come up, so the magneciter stays "on" more and "off" less. Above maximum load, if no breaker or fuse trips first, magneciter stays "on" full time and generator terminal voltage never reaches the 'fire down' voltage. Magic smoke soon appears!
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  #39  
Old 08-27-2012, 07:58:38 AM
BergmanJ BergmanJ is offline
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Default Re: Magniciter Theory FAQ

GHanners,

In response to #36 above: Yes, "regular" recovery is just fine; and, yes, the listings shown are "better" than the originals (more current capacity, and higher PIV).

"Power" (in #37) also has a good replacement for the whole bridge; my recommendation was to provide an "original-mount" part, which may seem easier for some folks.

Regards, JLB
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  #40  
Old 01-29-2013, 09:25:59 PM
Generactech Generactech is offline
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Default Re: Onan Magniciter Theory FAQ

I have several magniciter onan gens in my stash of older units. I have been searching for a simple way of being able to convert these 480 volt units to a more usable 120/240 unit.

I was looking at changing the 425 ohm resister (#3) to a 200 ohm to lower the voltage going into the voltage control reactor. any ideas as to helping me out would greatly further my efforts. I was thinking if it worked to add a DPDT switch to change the out put from 120/2540 to 480/277?
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