Any Honda generator experts Here?!??

[SkippyKtm]

Hi Guys, hopefully this isn't too off topic, I posted this question over on Do it yourself forum, but its deader than a doornail, Anyway, I have a EB5000 Honda generator that I picked up for a song at a swap meet. The GX340 engine had a broken rocker arm stud and worn push rod guide, which I fixed and the engine runs great, but the generator doesn't produce power. I was told by the original owner that it was producing power just fine before the engine quit and he seemed fairly honest about it.
The generator portion is a Sawafuji and has a model number of B 50 and no. A LL 6601 stamped beneath the model number as well. The control panel is also a Sawafuji and it is also a B 50 Model with a no. A LL 5798 beneath that. It has a frame number of EA7-3152768 and the engine number is GC05-3045988.
I pulled the generator cover off and blew the dust out of the windings and they all look good -nothing burned up in there. I pulled the control panel apart and there is nothing obviously wrong in there either. When I run the generator and check it with my dvm it shows it producing .2 VAC on the hot legs with the breaker on and 0 VAC with it off. Honda isn't very forth coming with its schematics or service manuals, I do have an owners manual but that doesn't help much.
Thanks for your help!

 

[bullseye13]

I have only messed with a few generators, however the best thing to do is get a service manual for any generator and it will help you troubleshoot, or better yet get the honda one you will need. Being that it does have some, but very little juice it dosent sound like a loss of residual magnetism. It is likely, however that you have a voltage regulator failure, or worse yet a bad stator or windings. Disconnect what you need to in order to test the stator and field windings. Make sure they have a reasonable amount of resistance, and not a short or open circuit. It is more complex to test the voltage regulator, but that is where the manual will help.

I hope this helps.

 

[SkippyKtm]

Thanks bullseye! Yes, that helps and I appreciate it. I put a request in for a service manual in over at the beg for manuals thread, maybe that will pan out. I'll probably continue working on it tomorrow, hopefully I'll have a manual by then too. I still can check for shorts and open circuit on the windings even if I didn't get the manual.

 

[lfnh]

fwiw, check the stator ring surface and clean if rusty or dirty.

Physically check the brushes and connecting wires - mine showed
electrical continuity, but when i pulled the brush holder, one of the
brushes had cracked and separated from the spring. $6.00 fix.

Check fuses, circuit breaker. Especially check push button breakers
with DVM.

A quick check of the core alternator AC field output can be done with a DVM:

Disconnect core alternator wiring harness to control panel - usually one n-way plug.

Identify the AC leads on the alternator plug and attach DVM, set to measure AC voltage.

Identify the stator brush leads on the alternator connector plug and their polarity. Usually the outer brush (furthest from engine) is the positive, but check your schematics.

Start the generator.

Attach leads from 12 volt DC source (battery), paying careful attention to correct polarity to the stator brush leads. actually a 9 v transistor battery can be used in a pinch.

When the 12 DC leads are connected, the DVM readings should begin rising, from .2v to 30, 50, 90, 120. The AC output of the alternator will continue rising very quickly without a voltage regulator to control the upper limit of AC output. So when the DV read 90 or so volts disconnect the 12 source leads, and shut it down. Note the AC output will rise quickly without limit, so be prepared to disconnect the 12 VDC leads quickly.

If the DVM shows rising AC, the problem is out board of the alternator core.

If the DVM does not show any increase in AC reading, suspects would be armature or field windings or bad brushes/stator.

Things to suspect would be the voltage regulator or system controller (if your model has one of these)
​

sorry for the long ramble.

 

[SkippyKtm]

Thanks ifnh, I'm going to be much wiser by the time I get this fixed. I'll let you know the results, and thanks for taking the time to help me out!

 

[lfnh]

I'm hoping it's simple - like a cheap set of brushes.

 

[SkippyKtm]

fwiw, check the stator ring surface and clean if rusty or dirty.

Physically check the brushes and connecting wires - mine showed
electrical continuity, but when i pulled the brush holder, one of the
brushes had cracked and separated from the spring. $6.00 fix.

Check fuses, circuit breaker. Especially check push button breakers
with DVM.

A quick check of the core alternator AC field output can be done with a DVM:

Disconnect core alternator wiring harness to control panel - usually one n-way plug.

Identify the AC leads on the alternator plug and attach DVM, set to measure AC voltage.

Identify the stator brush leads on the alternator connector plug and their polarity. Usually the outer brush (furthest from engine) is the positive, but check your schematics.

Start the generator.

Attach leads from 12 volt DC source (battery), paying careful attention to correct polarity to the stator brush leads. actually a 9 v transistor battery can be used in a pinch.

When the 12 DC leads are connected, the DVM readings should begin rising, from .2v to 30, 50, 90, 120. The AC output of the alternator will continue rising very quickly without a voltage regulator to control the upper limit of AC output. So when the DV read 90 or so volts disconnect the 12 source leads, and shut it down. Note the AC output will rise quickly without limit, so be prepared to disconnect the 12 VDC leads quickly.

If the DVM shows rising AC, the problem is out board of the alternator core.

If the DVM does not show any increase in AC reading, suspects would be armature or field windings or bad brushes/stator.

Things to suspect would be the voltage regulator or system controller (if your model has one of these)
​

sorry for the long ramble.

Great Post! I cleaned the stator ring surface as the resistance across the brushes was 90 ohms, and after cleaning they were at 60 which is Honda spec, but no luck. So i pulled the brushes off the stator and found a brush not floating freely, cleaned the dust out and reassembled, no luck. I pulled the avr, attached a 12v batt to the brushes and read the main winding voltage and it only rose to 1.9 vac. I checked resistance across the stator windings and I get only 1 ohm (those I think are the 2 blue wires that go to the AVR, they're in a 4 terminal connector with only 3 terminals being used and the remaining wire is white). So, I hope I'm wrong, but I think the stator windings could be shorted. What do you think?

 

[lfnh]

Apologies for delay in getting back here.

Thanks for the test numbers.

First, a quick correction to my testing post to avoid confusion:

1. all my references to stator ring should read slip ring.

For all these tests, turn auto throttle off, so engine runs at full speed.

Before getting into more DVM tests, can you make a simple test with generator running by plugging in a 110 V trouble light with 100watt bulb ?
First to top receptacle.
Next to bottom receptacle.

Slip ring ground fault test can be made by disconnecting avr plug and measuring resistance of each brush lead by itself to ground. ground = end of rotor shaft (cleaned). Engine off. Set DVM to mega-ohms for this reading. Connect DVM lead to first brush lead in housing connector, other lead to the rotor shaft ground. Make same test for the second brush lead.
DVM should = infinite resistance (no value, so to speak) for both tests.

Assuming the light test fails, a DVM test of the the brush voltage with the generator running may shed some light on the problem. For this test set the DVM to DC volts. Clip the DVM leads to the brush leads and start the generator (actually just cranking should be enough speed). Write down the low and the peak reading.
Should see the DC volts range from 10-12 VDC cranking, to 24-30 VDC at run speed.

I'll check back later and in the morning.

 

[SkippyKtm]

I retried your first test and The generator passed! I first tested it with the red/white and gray/blue wires connected (the wires that lead to the control panel) and got just 2.3vac. I then disconnected the red/white and gray/blue wires and tried again and got over 75 volts on both sides! It looked as though it was going to keep going higher so I removed the 12 volts when it climbed over 75 vac as I tested both main windings, I didn't want to smoke it. It must be something in the control panel holding it down.

 

[lfnh]

Thank you for the test. Good detective work.

In a nutshell, it appears the core alternator (rotor, slip rings, brushes and most importantly, the field coils (where the AC is produced) are working.

The AVR basically monitors the AC load, and makes adjustments to maintain AC voltage and current, by regulating the DC sent to the brushes (slip rings) which in turn control the strength of the rotor's magnetic field and consequently the saturation of the field coils.

So, if the AVR can't sense the AC output, or can't control the DC to the brushes, the generator appears dead, when in fact the AVR has failed.

A lot of generators, have a no load circuit which allows the unit to idle until there is an AC load detected. Then the throttle is moved to WOT and the AVR functions as above. Turning off the Auto-Throttle keeps the generator at WOT with AC volts usually set at 124-130 (no load) AND the cycles = 60.
So if a 100 watt bulb is used to check the AC at the receptacles, no damage will happen to the bulb and generator if the AC is out of range or the cycles isn't 60.

Most AVR's are potted (filler poured over the components) to protect against dust and vibration and so are not generally repairable at the component level.
If the generator stopped while under load, there can be an instantaneous reverse current spike that will get past the protective diodes to the transistor on the AVR and short it. There may not be any visible or telltale smell inside the AVR.

I'm sure you have checked the wires coming into the AVR for continuity, but it might be worth re-checking with the DVM set to mega-ohm resistance so to catch a high resistance break or short to ground in the wires and the crimped connectors. Mating n-way connectors are also places to carefully check. Also include checking the Auto-Throttle wires would help.

If all the wires and connections check out, then the AVR is probably suspect.
Might scout around online for cost to replace AVR (prices will probably vary a lot).

I'll keep thread marked in case something comes up.
Lee

 

[Dreamweaving]

Similar Problem

Can you send me the link to the service manual for the EB 5000.

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Thanks