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Onan MME model 9mme a 1a - Help Needed


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  #21  
Old 08-13-2017, 09:20:44 AM
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Default Re: No ac input

Wayne, that was my youngest brother at around age 5. He's by the outlet with a knife and I'm thinking oh well he might as well learn about electricity. Zap! He gets up with eyes the size of silver dollars and I said spose you won't do that again. Mom yelled at me for the burned tip on the knife.
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  #22  
Old 08-13-2017, 09:51:31 AM
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Default Re: No ac input

Quote:
Originally Posted by Wayne 440 View Post
Here is an illustration of one somewhat dated test method.
That is how I started out. You will clearly find out if you have power.

I think I know the one he is talking about.It was a short production unit. Two years,didn't last long. I will look but I don't think I have a manual on it.

People need to understand. Just saying I have an Onan. Is like saying I have a car. Where do you start trying to help.
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  #23  
Old 08-13-2017, 11:27:58 AM
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Default Re: No ac input

I managed to find the MME parts manual. I can see why he is confused. It list
A transformer
Two bridge rectifiers
A voltage suppressor
Three different resistors depending on spec.
One diode.

Not clear on what is used on what spec.

It is the one I was thinking of. A short lived production life.
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  #24  
Old 08-13-2017, 01:10:10 PM
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Default Re: No ac input

In post 3 of this newly merger thread oldgenny posts model and serial number, I'll assume his current question (post 8) is for that same gen.

------------------
Look on page 7-3 and 8-3 of service manual 918-0500. Schematic shows flashing diode comes off starter circuit, looks like after the field winding flashing current returns thru diode bridge, thru 120V neutral circuit, thru 120V neutral/ground bond, and finally to 12V ground ( frame). So it is important to have a 120V neutral to ground bond somewhere, or feild will not be energized (flashed with 12VDC ) to start the bootstrap process of starting to make AC.

Odd that Onan broke up the schematic into 2 sections. Engineers like to see it ALL in one schematic so they can get the big picture. Guess marketing or printers wanted it in 2 pieces

-----------------
Do you have the manual? If not use this link , then press control-F to bring up search. Type in MME you'll find the manuals. The service manual will be the most helpful one.

http://www.twinslan.net/~n0nas/manuals/onan/

Last edited by len k; 08-13-2017 at 01:27:08 PM.
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Old 08-13-2017, 01:34:14 PM
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Default Re: Onan MME model 9mme a 1a - Help Needed

when i was 4 years old, i touched the prongs on the plug of the extension cord i was plugging in, to see what would happen, no "TR" tamper resistant outlet that they now mandate, would have stopped that

another time a few years later, i used a butter knife to touch the nichrome wire heating element in the toaster, at that time i knew enough about electricity, not to go sticking things into outlets and such, BUT... i didn't know that nichrome wire wasn't insulated
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  #26  
Old 08-13-2017, 01:50:38 PM
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Default Re: No ac input

it is an onan model 9 mme a 1a checked it myself while I was working on it. the serial no. is I870940696 i am a little mechanically and electrically inclined I don't just stare at the problem I test just like the shop manual says but it is hard to tell which terminals to test especially when all the wires are all white and the writings are small. I don't just stand there with my thumb up my nose I was a building engineer for 18 yrs before I retired and I have been an auto mechanic since I was 14 and that was many years ago. i am trying to download pictures to my lap top from my wifes cell phone.

Quote:
Originally Posted by oldgenny View Post
it is an onan model 9 mme a 1a checked it myself while I was working on it. the serial no. is I870940696 i am a little mechanically and electrically inclined I don't just stare at the problem I test just like the shop manual says but it is hard to tell which terminals to test especially when all the wires are all white and the writings are small. I don't just stand there with my thumb up my nose I was a building engineer for 18 yrs before I retired and I have been an auto mechanic since I was 14 and that was many years ago. i am trying to download pictures to my lap top from my wifes cell phone.
i have the shop manual i would just like to know who put all the wires the same color

yes and it is a 9mme a 1a
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  #27  
Old 08-13-2017, 02:31:14 PM
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Default Re: Onan MME model 9mme a 1a - Help Needed

Look on page 8-3 in this manual for output wiring like Len mentioned.:

http://www.twinslan.net/~n0nas/manua...0(06-1990).pdf


Onan made all the wires white. I'm old and I have a very hard time reading the wires, I have to clean them carefully as to not remove the markings, get a flashlight and a magnafying glass and decipher the letters/numbers.

Or please post a picture of what you are asking about!

Last edited by nothingbutdarts; 08-13-2017 at 02:32:35 PM. Reason: added info.
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  #28  
Old 08-13-2017, 04:36:12 PM
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Default Re: Onan MME model 9mme a 1a - Help Needed

Wires have faint numbers near the connectors.

Before I knew that, I just traced all the wires to see where they went , it's a small gen. Heck in a 20 car commercial garge I traced and numbered all wires in conduits to see how some nut job had modified the building wiring.

( to get more amps for an outlet they paralleled TWO SEPARATE 20 amp branch circuits to run an air compressor. And circuit went on to power ceiling florescent lights, small gauge ballast wires....40 amps

Last edited by len k; 08-13-2017 at 10:49:36 PM.
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  #29  
Old 08-13-2017, 10:16:35 PM
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Default Re: Onan MME model 9mme a 1a - Help Needed

I found a new Genajunk unit one time. All blue wires no markings. Who ever wired it up knew what they were doing. Didn't help me standing on a hill top. With snow blowing around. I talked about everyone's mother at Genajunk.
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  #30  
Old 08-14-2017, 09:05:30 PM
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Default Re: Onan MME model 9mme a 1a - Help Needed

I tried calling onan for the parts but there is none in stock in North America the only ones are in Belgium for 87 dollars each plus shipping and it doesn't come with a jar of lubricant. is there a substitute part I could use. I took the bridge rectifier off and there was no heat sink paste underneath so maybe it just overheated. I have pictures on the cell phone but I am not sure how to get them onto my laptop.
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  #31  
Old 08-14-2017, 09:23:07 PM
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Default Re: Onan MME model 9mme a 1a - Help Needed

Bridge rectifiers are somewhat generic. Are there any numbers on the part?
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  #32  
Old 08-14-2017, 09:38:25 PM
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Default Re: Onan MME model 9mme a 1a - Help Needed

Wait a minute, you were initially asking about a flashing diode, now you talk of the bridge rectifier.

As far as powering the rotor : There should be:
--- a single diode (CR1 page 7-3 of service manual) . While cranking, it energizes/flashes rotor to start making AC.
---and a diode bridge ( CR21 , page 8-3 of service manual). It rectifies AC for rotor while running.

There is also a bat charging diode bridge ( CR2 page 7-3 of service manual)

Last edited by len k; 08-14-2017 at 10:42:32 PM.
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  #33  
Old 08-14-2017, 11:02:00 PM
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Default Re: Onan MME model 9mme a 1a - Help Needed

Try Allied Electronics out of Fort worth Texas. A bridge is a common item.

If you need CR-1/ 305-0653. Check out the internet they are all over the place for 15.00/20.00 dollars. When looking for Onan parts. Enter the number to the system. Most will pop up at cheaper prices.
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Last edited by Billy J Shafer; 08-14-2017 at 11:14:23 PM.
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  #34  
Old 08-14-2017, 11:29:30 PM
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Default Re: Onan MME model 9mme a 1a - Help Needed

Generic 5 amp 400 volt PIV diode is ~ $2-5 ,just check that the terminals are convenient for you. The terminals are available in many types, stud, solder loop, spade terminal, bare wire , ect......

See post 22 and 23 of https://www.smokstak.com/forum/showt...t=99938&page=2

Last edited by len k; 08-15-2017 at 12:08:54 PM. Reason: solder loop , wire
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Old 08-15-2017, 12:03:04 PM
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Default Re: Onan MME model 9mme a 1a - Help Needed

If you need the Field Current Rectifier CR21 (diode bridge to rectify AC to DC for the rotor) you may need diode rated at more amps.

Page 8-10 of service manual implies rotor voltage span is 18 to 60 volts DC. And page 13-11 says rotor ohms is 13.4 +- 10%. From ohms law rotor amps might max out at 60/12 = 5 amps so good to go with 10-15 amp or more bridge. And since it's tied to the 120 V winding I'ld go with a 600 PIV or more. I go high on amps and PIV just since they are only pennies more and it gives more safety margin/reliability. Typical in engineering to calculate what you need, then double it for a safety margin.

Last edited by len k; 08-15-2017 at 12:47:16 PM.
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  #36  
Old 08-15-2017, 04:54:44 PM
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Default Re: Onan MME model 9mme a 1a - Help Needed

that cr 1 is what I need but I don't know where it is at on the machine or how to test it. if I had a picture I could tell where it is at. in case it was forgotten it is a mme a 1a. the shop manual says the generator has one but not where it is at. every time I put the part no. online it comes up not found. I got good oil pressure now that the leaks are fixed and the oil changed again. who sells the proper oil filter for this gen set? I don't trust napa's guess.

when I type in 305-0653 it comes up as a bridge rectifier is that what cr-1 is?
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  #37  
Old 08-15-2017, 05:15:57 PM
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Default Re: Onan MME model 9mme a 1a - Help Needed

See my post # 32, above. CR1 is a single diode.
But for convenience you can wire up just one diode of a diode bridge. But have to double the amp rating of bridge.

Not sure where it is located , but if you trace the wiring and compare to manual schematic you should find it.

Since feild is ~ 13 ohms and flashing voltage is ~ 12VDC ( car bat) current thru the diode is ~ 1 amp. So I'ld use at least a 2-3 amp diode ( can go higher), would prefer a 5 amp one since it's literally only a few pennies more. A standard PIV of ~ 600 should be good., but can go higher

To test a diode can just take it an put it in series with a light bulb and battery... either 1.5 V or 12V . If diode is good the bulb will light with diode connected one way but not the other way. If you have an ohmmeter you can use it to do the same thing, see picture. ( the top pic is a diode bridge, 4 diodes)
.

Last edited by len k; 08-15-2017 at 05:27:02 PM.
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  #38  
Old 08-15-2017, 07:02:28 PM
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Default Re: Onan MME model 9mme a 1a - Help Needed

Quote:
Originally Posted by oldgenny View Post
that cr 1 is what I need but I don't know where it is at on the machine or how to test it. if I had a picture I could tell where it is at. in case it was forgotten it is a mme a 1a. the shop manual says the generator has one but not where it is at. every time I put the part no. online it comes up not found. I got good oil pressure now that the leaks are fixed and the oil changed again. who sells the proper oil filter for this gen set? I don't trust napa's guess.

when I type in 305-0653 it comes up as a bridge rectifier is that what cr-1 is?
Yes it is a bridge. Some are round but most onan used were square.
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  #39  
Old 08-15-2017, 07:07:46 PM
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Default Re: Onan MME model 9mme a 1a - Help Needed

IF a diode bridge sounds like they are just using one diode of the bridge and leaving the other diodes unconnected ( diode bridges have 4 diodes as you can see in top picture of my post 37

Here's one picture of a diode bridge https://www.bing.com/images/search?v...=47&ajaxhist=0

Last edited by len k; 08-15-2017 at 07:18:02 PM.
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  #40  
Old 09-04-2017, 12:39:26 PM
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Default onan found out problem just need parts

fixed the low-pressure switch, changed the oil and filter again, now i have oil pressure. but, it still won't stay running. it is an onan 9mme a 1a that's what's printed on the tag on the generator. so I attempted to check out the electrical and noticed it wasn't producing ac and looking at the manual it said it had to produce at least 90v to kick in the controls and it was not. I found two bridge rectifiers. the wiring schematic only shows one and onan said the cr1 was a drawing error there is no such device. but they would sell me one for 81 dollars out of belgium. so how does it excite the generatore to start producing and what are the specs on the bridge rectifiers so i can go to radar or radio shack and buy one for 6 bucks? what he needs is a modern generator that puts out more than 9,000 watts 120v ac and is easier to service.
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