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Onan 4.0 CCK Low Voltage


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  #1  
Old 11-01-2005, 05:19:47 PM
JerryH JerryH is offline
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Default Onan 4.0 CCK Low Voltage

I recently acquired an Onan genset, model # 4.0CCK-1R/6900P, SN 0272411579. It starts and runs fine, however the output voltage is very low, if any. Does the unit need to be grounded to work?

Also, where can I get repair/service manuals for this genset? Thanks,
-Jerry
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  #2  
Old 11-01-2005, 09:30:23 PM
Gunny Gunny is offline
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Default Re: Onan 4.0 CCK Low Voltage

Jerry:
You should be able to get a manual from Onan. Those are good solid well made machines designed to last a very long time. Make sure it is running at the correct speed before doing anything else. Engine speed directly regulated output voltage. Make sure the brushes are not bound up in their holdrs and that the slip rings are clean. How low of voltage are we speaking about?
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  #3  
Old 11-01-2005, 10:27:25 PM
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Billy J Shafer Billy J Shafer is offline
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Default Re: Onan 4.0 CCK Low Voltage

Just as Gunny told you check the speed should be at 1800 rpm.Then check the brushes and slip rings.Let us know what you find.
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Old 11-02-2005, 11:44:00 AM
JerryH JerryH is offline
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Default Re: Onan 4.0 CCK Low Voltage

Thanks for the info. While I wait for a service manual, can someone guide me through checking/cleaning brushes/slip rings?

I checked again last night and I'm not getting enough to get a good reading. The meter is showing less than 1 V, which I'm guessing means there is no output.

-Jerry
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Old 11-02-2005, 12:33:21 PM
Zeromedic Zeromedic is offline
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Default Re: Onan 4.0 CCK Low Voltage

Hi Jerry.

Engine off, battery disconnected.

Start by pulling the generator end covers. Loosen the 2 screws that clamp the large band around the end, then remove 2 small bolts that hold the endcap in place.

The endcap should fall free, and you should be able to slide off the band.

Inspect everything you find. Blow out dirt and cobwebs etc with a shop vac and soft brushing. Look for burnt or broken wires, or loose terminals.

There will be 2 separate brush assemblies, 1 set runs on the commutator surface - the segmented or toothed looking part that spins. This is the DC part of the generator, for starting and charging, and if your CCK is starting and running, it is working now.

A -1R should also have 2 smooth slip rings, likely with 2 paralleled brushs running on each surface. These provide the AC ouput. You can wipe the sliprings clean, maybe with a clean cloth and some alcohol. And make sure the brushes slide in/out of their holders, and are being pressed against the slip rings.

That should get you started, let us know what you find when you get the covers removed.

Steve
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Old 11-02-2005, 02:20:53 PM
JerryH JerryH is offline
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Default Re: Onan 4.0 CCK Low Voltage

I'll get started tonight. It starts and runs great (the choke needs to be manually held until it warms up, also quite a bit of oil on the plugs). I'll change oil, plugs etc., and repalce the fuel line which is a bit beat up. Is it critical that it be grounded? I suppose so, at least for safety's sake.

-Jerry
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Old 11-02-2005, 03:02:18 PM
Zeromedic Zeromedic is offline
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Default Re: Onan 4.0 CCK Low Voltage

Standard for any generator is to connect the frame to a good local earth ground or a ground rod.

That said, no it's not critical to the proper operation of the genset for it to be grounded. It will (or won't) generate electricity either way. As you suggested, the ground is for safety reasons. You don't want to be standing outside in the rain, and get a poke when you touch something metal on the generator.

If the generator is not hooked to any external wiring yet, just sitting on the floor or your workbench, there shouldn't be any circuit path back thru you that would include ground, so you're pretty safe.

You still don't want to touch any bare wires or terminals with the engine running.

This was probably a motorhome generator originally. Few mh's are grounded when they are using generator power.

Which brings up another thing to check:

If this was originally in a motorhome, has someone added a local outlet to it that you are plugging into to check voltage? Is there a fuse or circuit breaker box wired in?

If so, while you are examining these, wiggle the wires going to them. I've seen home class receptacles with solid wire added many times. The wire can harden, become brittle, and crack from vibration.

Also, your generator can supply over 30 amps on a single 120 volt lead. Most home style $0.50 receptacles are only good for 15 or 20 amps. I've seen more than a few outlets cooked internally by overloading.

Steve
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Old 11-02-2005, 04:52:28 PM
JerryH JerryH is offline
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Default Re: Onan 4.0 CCK Low Voltage

Yes, an external 30A breaker box and another receptacle box were added. I checked voltage on the receptacles first, and when there was none, went to the lugs in the breaker box. No joy. With a wiring diagram, I suppose I could trace it back even further and see what I get.

-Jerry
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Old 11-02-2005, 08:53:35 PM
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Billy J Shafer Billy J Shafer is offline
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Default Re: Onan 4.0 CCK Low Voltage

Email me and I can send you a copy of the print.My email billyshafer4@aol.com
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Old 11-03-2005, 12:12:55 PM
JerryH JerryH is offline
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Default Re: Onan 4.0 CCK Low Voltage

I sent you an email
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Old 11-03-2005, 12:21:21 PM
JerryH JerryH is offline
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Default Re: Onan 4.0 CCK Low Voltage

OK, I removed the end cap and blew out all the cobwebs/dust and inspected/cleaned the brushes/sliprings. All brushes are able to move freely in the holders, 4 on the commutator, and 4 on the 2 sliprings. I disconnected the 2 wires that are connected to the external 30A breaker and checked the voltage at that point. Still, only about 3V output.

Assuming it is running at 1800 rpm, is there anything else I can check?

I called the local Cummins shop and they can order manuals for me. Also gave me an 800 number which they said was Onan tech support, who could also help me troubleshoot the problem.

-Jerry
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Old 11-03-2005, 06:46:15 PM
JerryH JerryH is offline
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Default Re: Onan 4.0 CCK Low Voltage

Just spoke with Cummins tech support. Here's what they suggested I do:

0. Inspect and clean brushes and slip rings. (That's what I did last night)

1. Pull the AC brushes out and check isolation of brush holder to chassis. If there is a short, insulate brush holder from chassis. Otherwise, continue to step 2.

2. Check voltage between AC brushes. Take wires off brush riggings and check voltage brush to brush (engine on - be careful). There should be voltage at this point. If not, goto step 3.

3. Check isolation of slip rings from ground. Remove all AC brushes and check isolation of each slip ring to chassis. If there is a short, we have a big problem.
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Old 11-03-2005, 07:01:45 PM
Zeromedic Zeromedic is offline
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Default Re: Onan 4.0 CCK Low Voltage

The next thing I'd check is to make sure the armature AC windings aren't open or shorted.

Go to resistance mode on your VOM/DVM, short the probes to each other to get a baseline for the resistance of the leads themselves. Usually about .5 ohms. Or 0.0 ohms on some autozeroing meters.

Next, check the resistance of the AC winding by laying 1 probe on each slip ring. Don't use the tip of the probe. The slip rings are soft copper, and the probe points may gouge them.

I don't have an exact spec handy, but I'd expect a fairly low reading in the 5-10 ohm range. What you Really don't want to see is an open circuit, or anything up in the 1000's of ohms or higher.

If this first test is ok, then check for any resistance between either of the slip rings and the body of the armature. Ideally this will be infinite, or at least up in the megohm region.

All the above test should be done with the slip ring brushs lifted. Scraps of paper work fine slipped between the brush and slip ring.

Good luck. Hope your armature isn't cooked open.

Steve
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Old 11-04-2005, 11:53:31 AM
JerryH JerryH is offline
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Default Re: Onan 4.0 CCK Low Voltage

I checked the brush holders and slip rings. No short between the holders and chassis, nor between slip rings and chassis. The resistance between the 2 slip rings is < 10 ohms. So far, everything looks OK, but I haven't checked AC brush output with the engine running yet. Am I missing anything?
-Jerry
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Old 11-04-2005, 07:18:36 PM
Zeromedic Zeromedic is offline
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Default Re: Onan 4.0 CCK Low Voltage

Hi Jerry,

Your readings all sound good.

When everything is hooked up and all connections are good, those 2 slip rings are connected directly to the blades of your output receptacle.

I'd put everything back together, and check the resistance across the outlet. It should be just about the same as your measurement across the slip rings.

One side (one brush) is likely grounded multiple places during normal operation, maybe directly to the frame at the brush holder, again to a bolt inside the control box, and again in your added breaker box if it has a bonding screw installed thru the ground bar.

The hot side should run from the brush holder, thru the gen head harness into the control box to an insulated post, then out to your external box.

Your set is starting from 12 volts, and charging its own battery while it is running, right? Easy check for charging, if it doesn't have a panel mount ammeter, is to watch the battery voltage with your meter. After starting it should climb above the original battery voltage. 13.5-14 volts or so.

Steve
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Old 11-04-2005, 08:25:21 PM
JerryH JerryH is offline
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Default Re: Onan 4.0 CCK Low Voltage

Yes, it's starting from 12V. I'll check charging voltage this weekend. Thanks, everyone, for all your help!

-Jerry
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Old 11-19-2011, 04:39:30 AM
LiverpoolDave LiverpoolDave is offline
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Default Re: Onan 4.0 CCK Low Voltage

You can use a Multimeter to check the Electrical Resistance of the coils across the brass slip rings that Carbon brushes ride on, and connections in Circuit box this will confirm all is good there, I don't know exact readings on these but low Ohms on most Generators I have worked on 2-5 Ohms or thereabouts. If they are ok & wirings your units been dormant a long time it may possibly need 'flashing', using a 12v battery charger (only low 1-2 Amps couple of seconds) re magnetises rotor often. I have had several where this has brought them back to life.
Choke is the same on my CCK been wrongly connected I think, by the way beware of the 't' coarse mixture adjustment on carb, even 20-30 Degree alteration makes a big difference to good running & economy.
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Old 10-14-2017, 08:55:11 AM
Al Aliff Al Aliff is offline
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Default Re: Onan 4.0 CCK Low Voltage

Hello ,
My Grandfather gave me his Onan 4.0 CCK, Gen, mounted on a custom trailer, with long log splitter, It has not run in ten years, It has been inside barn with cover. I read you were having problem with the board I cannot find to buy. So I thought I would ask for help. I need all three control panels because the ones I have are cracked and broken. The unit looks to be in good shape and I have put wire numbers on all the wires and old control boards. So I am now hoping to find a match and put everything back as all replacements and new. My friend wants me to make a video of the Onan running so he can hear the sound. So I have work to do and parts to order..
I found the Onan boards; 300-1227,
300-C859/300-0859,
but not the; 332C1491/332C0491.
I think this is the voltage regulator.
How did you repair your panel? Or better yet Where can I buy the three panels you used for your repairs? Maybe I could use your supplier for parts? I think I can put everything back together If they are the same match and new.
I was able to have it run a little from start to Ground. Sounded smooth. Now I just need parts.
I cannot find a board that even looks like the old one. I would appreciate any insight.
Thanks, billyshafer4@aol.com <billyshafer4@aol.com>;
Al

Hi, Does anyone have Onan 4.0 CCK 3CR manuals, Service, parts, how to replace parts, How to maintain, manuals. I have an Onan that needs all three control boards. I can find the 300C859/300-0859, the 300-1227, but not the 332C1491. I think this is the voltage regulator control board. Have you replace all three of these panels?
Where did you find your parts? Where can I find replacement parts to match?
I want to get this running to make a video of how smooth the unit sounds.
Thanks for your insight and help.
Al
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Old 10-14-2017, 11:48:01 AM
nothingbutdarts nothingbutdarts is offline
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Default Re: Onan 4.0 CCK Low Voltage

Look here for all the manuals you need:


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

Also, you might give Flight Syatems a call and see if they can help you on your boards.

http://www.flightsystems.com/
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