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Onan Magniciter Theory FAQ


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  #71  
Old 04-03-2017, 12:38:39 PM
Vanman Vanman is offline
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Default Re: Onan Magniciter Theory FAQ

Hi Leon, yes I'd love to have a schematic! I'll add it to the one I got from you for your battery charger. Looks like your generator shed would be a fun place to visit. Wish I lived closer.

I had to Google Schmitt Trigger. Interesting.

Keith
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  #72  
Old 04-04-2017, 09:44:45 PM
Leon N. Leon N. is offline
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Default Re: Onan Magniciter Theory FAQ

Keith, I will write myself a note to send that off to you tomorrow. Oh, send me a PM with your email address.

Leon
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  #73  
Old 11-06-2017, 09:43:31 AM
JoeE. JoeE. is offline
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Default Re: Onan Magniciter Theory FAQ

Out of curiosity, looking for something to replace a magnaciter with, I read through this thread and found the discussion about Powertronics and their UVR500 and SE350...

After looking through their site, I find those two items on their "Discontinued Products" list...
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  #74  
Old 11-09-2017, 08:42:18 PM
zuhnc zuhnc is offline
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Default Re: Onan Magniciter Theory FAQ

Can any of the Magnecitor Guru's decipher these waveforms? One is no load, one is 50% load. 6MDJB-3R/2268R - 0368024947. I recently rewound the stator, and replaced all the rectifiers on the Magnecitor. With straight DC applied to the stator (battery only), the AC waveform looks normal, and indistinguishable from the commercial power waveform. The top waveform is AC output, as measured at E1-E2 on the Magnecitor. E1/E2 and T1/T2 are directly connected together at the end of the windings. I have the unit connected for straight 120VAC - T1/T3 connected as the hot, and T2/T4 connected to the chassis with a solid connection. The bottom waveform is DC at the F1 and F2 terminals on the Magnecitor.
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  #75  
Old 11-09-2017, 09:10:38 PM
Leon N. Leon N. is offline
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Default Re: Onan Magniciter Theory FAQ

Yes, I can relate to your observations noted in post 74. Back in 1970 when I refurbished my 7.5 JB equipped with the magneciter back end I was aware of possible TV interference when running on generator power. So Onan sent me a copy of their tech bulletin T-023 dated August 1964.

This is a brief 4 page document discussing defective television reception, RFI, input waveform distortion comparing commercial power versus asynchronous operation. I never noticed any problems but Onan does discuss asynchronous generator operating equipment employing magnetic amplifiers and some battery chargers which produce a notched wave form.

I do know the magneciter produces a notched waveform very similar to what you show.

Back in 1970 I had an oscilloscope and conformed the fact that the magneciters do not produce a clean waveform but one that is rich in the second harmonic. There is a notch on both the positive as well as the negative portions of the 60 cycle waveform. Your pictures do not seem to show that fact.

That's about all I can say. If you want a copy of T-023 send me a pm with your email address and I will send you a copy.
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  #76  
Old 11-09-2017, 09:55:26 PM
zuhnc zuhnc is offline
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Default Re: Onan Magniciter Theory FAQ

There is a decided notch in the negative portion of the AC waveform where the DC on the field is lower voltage. There is also a slight notch in the positive portion of the AC waveform, where the DC on the field is higher voltage. I had to increase the time constant of the scope to observe it. My question, and concern, is the imbalance in the DC drive to the field. I would assume it would be similar on both halves of the AC waveform. I do have a copy of the T-023 document, thanks to the fine individuals whom have made all the documentation available on the twinslan site. I do not know enough about magnetic amplifiers, in spite of reading all the documentation available, to investigate a specific area for faults. zuhnc
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  #77  
Old 11-09-2017, 11:15:44 PM
Vanman Vanman is offline
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Default Re: Onan Magniciter Theory FAQ

Is it possible that you have a bad diode, and your field is being supplied only with half wave rectification?
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  #78  
Old 11-10-2017, 04:49:05 PM
zuhnc zuhnc is offline
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Default Re: Onan Magniciter Theory FAQ

Yes, I had thought of that, as well as the "bias" wire going the wrong way through one or both of the gate reactors. So, I checked all of the rectifiers (approximately 0.52v drop) and bridge diodes (approximately 0.47v drop); they all check good. Reversing the direction of the bias wire through either or both of the gate reactors resulted in output voltage drop; no change in waveforms. If someone else has a scope, pictures of the waveforms from a known, good, machine would be enlightening. On my Fluke dual-trace scope, the upper waveform is the AC output, the lower is the field input, F1 to the scope lead, F2 to scope ground. Would one think that having the same ground for both scope inputs would give these waveforms? I will have to disconnect and disable the "B" input and remeasure. I will post results here; give me a couple of days, life (SWMBO) tends to slow down the Green Disease zuhnc
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  #79  
Old 11-20-2017, 10:55:37 PM
zuhnc zuhnc is offline
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Default Re: Onan Magniciter Theory FAQ

I have figured out where the anomaly in the DC field waveform is coming from. It turns out that the Fluke Scopemeter 123 I am using has the grounds tied together internally. So, one can not measure both the AC output waveform, and the DC field waveform simultaneously - no common ground point. The Magneciter is completely isolated from the generator chassis ground. The internal meter common ground was playing games with both waveforms. Here is the actual DC field waveform, isolated. The 26V is no load, the 30V is 1/2 load. You will notice the frequency indicated is twice the actual AC output frequency; the unit is running at 60-62Hz.Click image for larger version

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  #80  
Old 11-20-2017, 11:10:21 PM
Leon N. Leon N. is offline
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Default Re: Onan Magniciter Theory FAQ

Re your post 79 pictures. I presume you are showing the DC voltage applied to the rotor with pulsating ripple which corresponds to the second harmonic associated with the knotches that distort the generator output AC waveform. Onan does spec the full load rotor voltage as 40 volts@400 watts.
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