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Onan Emerald Plus Generator Wont Stay Running?


Hello, I have an older ONAN EMERALD PLUS generator in my Class C RV. When I hit the start button,...

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  #101  
Old 12-07-2012, 03:12 PM
len k len k is offline
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Default Re: Onan Emerald Plus Generator Wont Stay Running?

From post 98....Checking for grounded (12V) generator
With engine off, regulator out, measure voltage (both with meter and 12Vtest light) at the regulator connector between pin 3 and +12V , you should see ~12V (full battery voltage)


While you are doing this repeat this test between pin 2 and +12V ,you should see ~12V (full battery voltage). This checks the wireing from pin 2 thru the t windings back to ground .(just trying to cover all the bases) Please post all findings.
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  #102  
Old 12-07-2012, 03:32 PM
grif grif is offline
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Default Re: Onan Emerald Plus Generator Wont Stay Running?

Quote:
Originally Posted by len k View Post
For now lets concentrate on one problem at a time.... why the regulator pins 2-3 are not receiving ~


Amen!!! How many times have I installed three or four other problems to repair later that had nothing to do with the original problem. Let me count the ways. This should be a sticky note.
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  #103  
Old 12-11-2012, 08:32 PM
KenS999 KenS999 is offline
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Default Re: Onan Emerald Plus Generator Wont Stay Running?

Len,

The weather is set to improve here shortly, will allow me to get back out there on Wed or Thurs. So, barring any unforeseen catastrophy, I should be able to post the latest results by Thurs eve.

Thanks,
Ken
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  #104  
Old 12-12-2012, 06:47 PM
KenS999 KenS999 is offline
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Default Re: Onan Emerald Plus Generator Wont Stay Running?

Len,

Results of latest tests (engine off/regulator out):

1) Regulator Plug Pin-3 to Frame = 0.4 ohms

2)Regulator Plug Pin-3 to Pin-9 =1.8 Megaohms
to Pin-10 =1.8 Megaohms
to Pin-11 =OPEN
to pin-12 = OPEN

3) Regulator Plug Pin-3 to 12VDC using DVM and Test Light=12.5VDC/good light.

4) Regulator Plug Pin-2 to 12VDC (thru T windings) using DVM and Light =12.5 VDC/good light.

5) Continuity between Regulator plug Pin-9 and F1 = good.

6) Continuity between Regulator plug Pin-9 and F2 = good.

7) Regulator plug Pin-9 to Pin-10 = 121 ohms (NOT GOOD). Pulled brush
assembly measured across rings = 24 ohms. Examined brushes, no binding, good travel in housings. Reattached brush assembly, measued 23 ohms. Cranked gen a few times, remeasured across brushes = 43 ohms, after sitting abit measured 30 ohms, and sitting abit longer=24ohms (dont know whats goin on there??) Recranked a few more times and remeasured = 24 ohms across F1-F2 (brushes).

8) As ring measurement appeared to remain stable at 24ohms, decided to externally apply 12VDC to F1-F2 and plugged in New Regulator. No Joy, only ran with start button depressed. Final measurement was across F1-F2 (brushes) =24ohms, reading remaining stable.


-Ken
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  #105  
Old 12-12-2012, 11:33 PM
len k len k is offline
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Default Re: Onan Emerald Plus Generator Wont Stay Running?

1 thru 6 sound good , you have continuity where is should be , and no shorts to grounds where there should not be....Very good

7) Regulator plug Pin-9 to Pin-10 = 121 ohms (NOT GOOD).
This is the problem that likely killed your new regulator. Back in post 67?, you said it was 26 ohms. Something is intermitant, you have to track it down and fix it or it can kill your next regulator. Sounds like the rotor and slip rings are likely good (if the resistance consistantly stays low when meauring between sliprings themselves). That is good, that only leaves the cheap brushes, connectors, and wiring.

The best way to track down intermitants, is to have them be bad , then without moving anything, probe arround with your resistance meter and find the bad section. To save work , try to find which 1/2 of the circuit is bad , cuts your job in 1/2. Say...start from either VR pin 9 or 10 and measure to it's slip ring, then repeat with other pin and ring. Hopfully one 1/2 will have alot more resistance than the other. Problems usually happen across joints and connectors , but wires can go bad internally.

If it's not bad now , with VR out, measure resistance between VR pins 9-10 , watch meter and wiggle the wires , connectors , hand rotate the rotor, etc looking for what increases the resistance. .

Ideas to try.
Check the brushes for cracks and wear (read page 8-14 of the manual ), check that the brush springs have tension, the braided wire from brush looks good and both ends look good , the wire's spade terminal are tight on the brush holder spade connector (on some gens they get brittle and loose). Recheck that the brushes move freely in the holder without binding or cocking. the holders are not cracked, that there is no crud under the brush were it touches slip ring. When engine is running ,check that the brushes are not dancing in the holder, from a lumpy/bumpy slipring. Reclean the slip rings (run engine , tape some scotchbrite to a paint stick and hold it to the sliprings.)


Overall here is what I suspect happened to your new regulator, in the past.
Back in post 67 you said the VR pin 9-10 resistance was ~26 ohms. When you installed the new VR and measured the B1-B2 voltage I suspect the pin 9-10 resistance stayed good. Then something happened (the intermitant ) and the gen's pin 9-10 resistance went up,the VR blew out, so there was no voltage to power the rotor, so the T windings (120) showed no output (~2 or 3 volts from resistual magnetism of the rotor).

Sorry for the long post, but I know you have a long drive to get to the gen.
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  #106  
Old 12-13-2012, 01:05 AM
KenS999 KenS999 is offline
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Default Re: Onan Emerald Plus Generator Wont Stay Running?

Quote:
Originally Posted by len k View Post
hand rotate the rotor, etc looking for what increases the resistance. .


(1) Dumb question, how can you rotate rotor by hand?


When engine is running ,check that the brushes are not dancing in the holder, from a lumpy/bumpy slipring.
(2)How can you tell if brushes are dancing?


I did observe this..... one of the rivets attaching the spade thru brush holder is somewhat loose. Im sure vibration during run would cause some movement. Each time I remove/reattach the brush assembly.... the resistance comes back within tolerance (24-28 ohms), After cranking the gen, then that when the resistance appears to " intermittently" go up.

So, when resistance goes beyond 28ohms across F1-F2 that would blow the VR ? It seems to me that in time, everyone of these generators would would fall victim to this condition? Is it an inherent design flaw? So, between the VR and the control board there isnt a failsafe breaker system to prevent this ?
Replacing the brushes might be an inexpensive option before reinstalling a good regulator? Any idea who would carry a replacement?

Thanks,
Ken
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  #107  
Old 12-13-2012, 11:32 AM
KenS999 KenS999 is offline
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Default Re: Onan Emerald Plus Generator Wont Stay Running?

I was able to find the brush block asembly (212-1285-S0) online. Runs 85 bucks plus shipping. That said, I might just drill out the original rivet and use a small bolt to secure it to the ceramic assembly. If I break it, I would have bought a new one anyway.

-Ken
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  #108  
Old 12-13-2012, 01:06 PM
len k len k is offline
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Default Re: Onan Emerald Plus Generator Wont Stay Running?

one of the rivets attaching the spade thru brush holder is somewhat loose
I think you found the problem. ALL connections can't be loose, or you can get intermitants. With meter across the connection, wiggle it , see if ohms change, check other connections too, might be more than 1 bad one. Clean the electrical surfaces before you bolt them back together. Maybe some locite threadlock to prevent your screws from vibrating loose, (if it is not in the electrical path.) Also look at fine wire from brush itself, does it look good ? Put ohmmeter across it and wiggle it.

While you have it apart, depending on brush wear might not be a bad idea to throw some new ones in.

Yes, it is a design flaw. Lot of people with electronic regulators have this problem, pretty common, no failsafes. Don't know what the resistance threashold for failure is , usually it's dirty/corroded sliprings, but any high ohms will do it. They say run every month to keep the slip rings clean. I suspect it takes several months of sitting for rings to get dirty/corroded. IF it's not run for a while, unplug regulator (to protect it), and clean sliprings with scotchbrite taped to a stick, while cranking engine.

Rotating rotor......Put a big allen wrench on the shaft at the gen end of the engine/gen. For safty remove spark wires (it can start), easier to rotate if you remove spark plugs.

Dancing brushes........ with holder installed on gen, see if you can look at brushes, and see them moving arround. Haven't seen your model in person, not sure if you can. Doesn't matter much I think you found the problem with the loose spade connector.

Don't know cheap suppliers, haven't bought parts for onans yet. They say ebay (also partsfortecks.com ??). Maybe someone else can advise Ken.

For $85 I'ld definately try fixing it , really small screws and drill bits are easily available. Homedepot, hardware store, etc.
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  #109  
Old 12-13-2012, 01:24 PM
KenS999 KenS999 is offline
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Default Re: Onan Emerald Plus Generator Wont Stay Running?

Len,

Then I will send the new regulator to Flight Systems to have it checked (wish I could find a local place). I will repair the brush assembly, clean slip rings again, and check for additional fluctuations in resistance beyond 28 ohms across brush assembly. My concern going forward is the lack of Field Flash voltage during crank. How can I troubleshoot/repair that issue?

Eventually, when I get the new regulator back, and verify constant 24-28ohms across F1 F2, is it then ok to plug in new regulator while externally applying 12vdc (flash) to F1 F2 and jumping coil and pump without risking damaging new VR measuring for 120VAC ?

If you have a better plan, Im open.

Thanks,
Ken
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  #110  
Old 12-13-2012, 01:46 PM
len k len k is offline
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Default Re: Onan Emerald Plus Generator Wont Stay Running?

**************
On the loose brush holder spade............ I assumed the current flows thru the spade and rivot. So the loose rivot is in IN THE ELECTRICAL PATH. I just looked at the manual page 8-14 figure 8-12, this may not be the case. You should look at your holder.

In the picture it looks like the spade is ONE U shaped peice of brass that is just physically held in place by the rivot ( rivot appears to NOT be in the electrical path). It this is the case, a mildly loose rivot would be ok. IF the spade is not ONE peice, say two J shaped peices of brass , then the rivot would have to be tight to maintain good electrical contact between them.


My concern going forward is the lack of Field Flash voltage during crank
One problem at a time, I wouldn't worry about that now. Lets get it making AC first. Worst case flash solution is ~$100 new control board., or solder in a new diode or relay.

Eventually, when I get the new regulator back, and verify constant 24-28ohms across F1 F2 .......
Once you find and cure ALL INTERMITTANTS so you get it to STAY CONISTANTLY at these low ohms, then it will safe to attach new reg. Otherwise new reg can die again.

You flash pin 7 of VR,,,, not F1-F2......With a good regulator,you can get fireworks if you flash F windings directly, without a diode. Reg starts working and F windings can have higher voltage that trys to flow back to bat , not good.(can kill reg also)

No problem jumping coil and pump to keep engine running.
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  #111  
Old 01-07-2013, 10:34 AM
KenS999 KenS999 is offline
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Default UPDATE Re: Onan Emerald Plus Generator Wont Stay Running?

Thought I would post an update on my ONAN. I sent back the New Voltage Regulator directly to Flight Systems for warranty inspection. After some delay, they are supposed to be sending me a replacement Voltage Regulator.

The temps have been very cold here in Northern Illinois, so wouldnt have gotten too much done till now.

Happy New Year,
Ken
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  #112  
Old 01-07-2013, 11:57 PM
len k len k is offline
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Default Re: UPDATE Re: Onan Emerald Plus Generator Wont Stay Running?

I know what you mean, few nights ago it was 6 degs F, 19 now. Outside, fingers get too cold to work when it goes below 32. The outdoor cats are warm though, 40, in the electric heated doghouse, built when I was 15.
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  #113  
Old 01-09-2013, 07:35 PM
KenS999 KenS999 is offline
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Default Re: UPDATE Re: Onan Emerald Plus Generator Wont Stay Running?

Len,

Replacement regulator came today from flight systems. I will call the retailer tomm. and try to find out if it was replaced because defective, or because Flight Systems was behind in repairs due to their recent move.

There may be a brief weather window later in the week for me to try it. Other than verifying 24-28ohms across brushes (pins 9-10), anything else I need to verify before plugging in the new regulator? I assume I will need to apply 12vdc to the brushes (pins 9-10)as well, as it was not being produced last time. Im guessing the gen will not start without it ?

Thanks,
Ken
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  #114  
Old 01-09-2013, 09:16 PM
len k len k is offline
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Default Re: UPDATE Re: Onan Emerald Plus Generator Wont Stay Running?

You first need to try to find out what killed the other 2 regulators and fix it or this one can die also, (gets expensive).

What do the slip rings look like , are they UNIFORMLY clean all the way arround (360 degrees)??
Are they shinny copper, or dirty black, are they grooved, pitted, wavy ??

First I would recomend a good recleaning of slip rings with a scotchbrite pad , maybe taped to a stick, with engine cranking, spark plugs out, regulator out. Keep your fingers clear.

Quote:
Originally Posted by KenS999 View Post
I assume I will need to apply 12vdc to the brushes (pins 9-10)as well, as it was not being produced last time.
No , do not put 12V to brushes when using reg, there will be much fireworks if it starts making power. If you have to ,you apply +12VDC to pin 7 of regulator till it starts making AC power (likely a few seconds at most)
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  #115  
Old 01-09-2013, 09:59 PM
KenS999 KenS999 is offline
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Default Re: UPDATE Re: Onan Emerald Plus Generator Wont Stay Running?

Hi Len,

The last time I cleaned the rings using Scotchbrite while cranking the starter, the rings really didnt get shiny like a new penny, rather a dull copper color. Would a pencil eraser be a viable alternative? I know some people use erasers to clean up electrical contact surfaces.

Thanks,
Ken

Thanks,
Ken
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  #116  
Old 01-09-2013, 10:07 PM
len k len k is offline
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Default Re: UPDATE Re: Onan Emerald Plus Generator Wont Stay Running?

I wouldn't, it could leave a residue, I would stick with scotchbrit.
Just wanted you to give it a real good cleaning, it's usually dirty sliprings that kills regulators. You never did find what killed the other 2.
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  #117  
Old 01-10-2013, 09:35 AM
KenS999 KenS999 is offline
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Default Re: UPDATE Re: Onan Emerald Plus Generator Wont Stay Running?

Quote:
Originally Posted by len k View Post
You never did find what killed the other 2.
No, and I am rather reluctant to plug in the replacement. In the mean time I have been trying to locate someone local with one of those "suitcase analyzers" manuf. by Flight Systems. I even went as far as contacting Flight Systems and was suprised to hear that they do not keep any data record of who they sell to? I found that to be rather odd. I would easiy let it sit thru the winter, but I am afriad the longer it sits unexercised, the harder it will be in spring to get it started.

Ken
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  #118  
Old 01-10-2013, 01:25 PM
len k len k is offline
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Default Re: UPDATE Re: Onan Emerald Plus Generator Wont Stay Running?

I don't know how good you are with looking at wiring for problems. If your experience in this area is light, you might consider having an experienced person give the wiring a look over for bad connections.

Usually the problem is dirty slip rings. You said you cleaned them, before the 2nd regulator died. I assume you did a good job cleaning both of them , all the way arround, no dirty sections. Can you post pictures of the slip rings

The "suitcase analyzers" (their pointman) are mostly just a convient way to do almost everthing I have told you to do so far. The only thing their better analyzer (think it's G-MAN) can do , that you can't , is do a hi-pot test on the windings. Basically it measures the insulation resistance windings to ground at ~200Volts vs the ~9 volts your hand meter uses. But I wouldn't expect that to be an issue.
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  #119  
Old 01-10-2013, 01:54 PM
KenS999 KenS999 is offline
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Default Re: UPDATE Re: Onan Emerald Plus Generator Wont Stay Running?

Quote:
Originally Posted by len k View Post
The "suitcase analyzers" (their pointman) are mostly just a convient way to do almost everthing I have told you to do so far. The only thing their better analyzer (think it's G-MAN) can do , that you can't , is do a hi-pot test on the windings. Basically it measures the insulation resistance windings to ground at ~200Volts vs the ~9 volts your hand meter uses. But I wouldn't expect that to be an issue.

Yes, the G MAN and from their ad/description:

http://www.flightsystems.com/GMAN_RVGENSET_TESTER.htm

I figured it to be more of an "idiot proof" troubleshooting analyzer that would simply spell out a bad VR, or a bad board, or an open or shorted circuit. Kind of like a functional test platform.

So, it sounds like I would be wasting my time hunting one of these down?

Ken
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  #120  
Old 01-10-2013, 02:08 PM
len k len k is offline
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Default Re: UPDATE Re: Onan Emerald Plus Generator Wont Stay Running?

In the past I've read about their gman box, it's just like their pointman box except it does hi-pot testing. You still have to use a hand meter with it , and interperate the readings. Not real advantage for you.

Only real advantage is you plug it into reg's gen connector and it gives you a convient place to plug in you meter. Not worth the expense unless you are a tech testing gens all day. Makes hooking up meter faster.
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