Author Topic: Another alternator problem  (Read 696 times)

Johndoh

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Another alternator problem
« on: May 23, 2018, 07:56:27 PM »
Hi guys, I bought a yanmar diesel generator 5.7 kw 10hp. Excellent engine but no power. I replaced the brushes still no power when a multimeter is connected. I am getting 4 volts from the outlet socket, any suggestions?
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dieselgman

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Re: Another alternator problem
« Reply #1 on: May 23, 2018, 08:20:10 PM »
Insufficient information provided... But you may need to "flash" your field. Restore magnetism if residual has been lost in storage.

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Johndoh

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Re: Another alternator problem
« Reply #2 on: May 23, 2018, 10:45:43 PM »
Hi G-Man The engine is an L100 not sure of the alternator brand it has brushed and an AVR and 110 and 230 v outlets and 12v battery charger. I have read several articles about flashing a generator I'm a little bit afraid of electricity and giants but not many giants in Ireland! Could I blow up the AVR by flashing could I blow up everything? I have a battery charger could I use the 6 volt setting to flash it? Thank you
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glort

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Re: Another alternator problem
« Reply #3 on: May 23, 2018, 11:09:18 PM »

Look on the bright side, it's not working now so if you do " Blow it up" you'll be no worse off!  :0)

Firstly, about all the " Blow up" You'll get will be a few sparks. Don't worry about them.  Some Lunatics like me like to make sparks and flashes and bangs for fun.... and we are still here!

I don't know about 6V, I always use 12 cause that's what I have in batteries etc. You could try 6 and if it does not work, then set your charger back to 12.
Give it a good hit too, some of them can be a bit slow on the uptake and you may need to do it a few times. Not sure what the correct Procedure is, I usualy do it when they are running.  Just make sure what you are holding is insulated in case you go back for a 2nd flash and the thing has come up between looking at the meter and looking at what you are doing.  You should probably try to flash the thing while it's not running first I spose.

If you can't get it to come up, next most likely thing would be the AVR.  I have done a few of these for different generators, mainly on friends boats.
Just buy a cheap universal one of ebay. They are under $20 hear and never had problems with them... except for said friends Buying the wrong unit for their genny. Even still, you could buy about 10 and still be in front on the onan and others I have done. They just plug in now and couldn't be easier to install.  friends have usually bought a spare so if they do have problems which seems common on boats, they can now plug the other one in themselves and eliminate one possibility of fix the problem.  Not aware of any chinese replacements I have put in failing in the last 3-4 years since I did a couple at once or beyond or the more recent ones.

The AVR is designed to handle the full output of the genny volt wise so hitting it with 12V won't do anything. They are usually Potted so you won't be able to hit anything you could damage anyway.

Only thing with those L series motors is they are Noisy buggers.  Most of the racket is mechanical and intake. The exhaust everyone Immediately suspects is pretty quiet but if you take the air cleaner off while it's running, the giants will be too scared to come near you!

Haven't played with any of mine for a while, Might be a good day to drag one out the shed and have a fire up! :0)

EdDee

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Re: Another alternator problem
« Reply #4 on: May 24, 2018, 08:13:19 AM »
Hi JD,

Not to undermine anybody here, but I had a similar problem with my yanmar clone autostart unit... It turned out to be the AVR unit that was kaput... Ordered a few off fleabay and when they arrived, plugged in and tested....

Found 2 things, the first of which was an electrical incompatability issue - there was a plug between the avr and gen with 4 wires going into it - when plugged in and running, there was very low output on the 220V terminals, it turned out that the pairs of wires were switched around, when taking a random stab at things, I switched the pairs around and all came right...

The second was a tricky issue that reared its head after the unit was tested standalone with isolated non-household loads (where it worked perfectly)... It turns out that the AVR, when mounted, had a heat sink sticking out of the potting and was shorted to earth when mounted to the genhead. as soon as N/E was coupled together by the addition of a household load (My N/E is connected at DB Board as well as pole) the slight raise in potential be the earth of the genset, being fed back into the heatsink which wasn't insulated from the control circuitry by the looks of it, caused the output voltage to cycle from about 50 up to 150V at about 5Hz...

Long and the short of it - Has the AVR been replaced? Does it look like a new chinesium one in better condition than the internals on the genset? If so, maybe the pin config on the plug is incorrect. If not, visit fleabay and get a couple.... (Oh, and make sure that the heatsink that sticks out the back of the AVR isnt shorted to ground...)

There are also one or two other 2pin connectors on the genhead proper (Besides the 2xsets of 110v outputs) - they are for auxilliary 12/24v generation to charge onboard starter batteries and provide sometimes a separate 12/24v output, once rectified, for the 12/24v dc outlet...

Cheers
Ed
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Johndoh

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Re: Another alternator problem
« Reply #5 on: May 24, 2018, 08:59:38 AM »
Thanks guys! I haven't replaced the AVR yet one has been ordered from Amazon.co.uk. It appears to have been strapped to an especially lazy tortoise but im hoping it will arrive eventually. This generator is another 50 quid buy. The starter motor wasn't working so it was left abandoned, I put in fresh diesel and a pull start and she started soon as the injector popped. I tried the drill idea to flash the alternator but still nothing at the brushes. It is a noisy bugger but Im not too bothered about that. I have just ordered a new brush box for it as well as replacing the brushes again the brush box will probably take a while. Thanks Glort I will try a car battery long as it won't fry ME the alternator can be repaired/replaced! Paul
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mike90045

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Re: Another alternator problem
« Reply #6 on: May 25, 2018, 04:58:59 AM »
When I flash a alternator/generator, I use an old style automotive jump pack and a taillight/stoplight bulb

The stoplight bulb provides a current limiting resistor, and some visual indication you did something, if med-dim. you flashed it
no glow, the winding is open, full bright, something is shorted.  The bulb also can provide some grace against frying the regulator or diode bridge if you hook up wrong.

some ideas
https://www.smokstak.com/forum/showthread.php?t=60336
http://www.dieselduck.info/machine/03%20electricity/flashing_generator.htm

The idea is the diode pack rectifies AC to DC and that is applied to the Field   That's where you attach the DC, at the AC pins of the diode bridge.  The diodes will steer the DC in the proper direction to re-magnetize the field.

In theory.  It works for me.


Johndoh

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Re: Another alternator problem
« Reply #7 on: May 25, 2018, 07:44:10 AM »
When I flash a alternator/generator, I use an old style automotive jump pack and a taillight/stoplight bulb

The stoplight bulb provides a current limiting resistor, and some visual indication you did something, if med-dim. you flashed it
no glow, the winding is open, full bright, something is shorted.  The bulb also can provide some grace against frying the regulator or diode bridge if you hook up wrong.

some ideas
https://www.smokstak.com/forum/showthread.php?t=60336
http://www.dieselduck.info/machine/03%20electricity/flashing_generator.htm

The idea is the diode pack rectifies AC to DC and that is applied to the Field   That's where you attach the DC, at the AC pins of the diode bridge.  The diodes will steer the DC in the proper direction to re-magnetize the field.

In theory.  It works for me.
#
Thank you this suggestion goes well with my idiot knowledge of electrics  simple and obvious!
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quinnbrian

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Re: Another alternator problem
« Reply #8 on: June 26, 2018, 02:42:33 AM »
Just flashed one today...pulled the car up  ::) hooked up the booster cables...disconnected the plus terminal on the rectifier , hooked a wire from the negative battery cable to the negative on the bridge rectifier ( leave the wire hooked up the the rectifier) , started the generator, with the volt meter on the output voltage, held the positive battery cable to the positive terminal the went to the rectifier ( the wire must be unhook from the rectifier...or you will smoke your rectifier) , look at the volt meter...when it gets to 115 volts, disconnect the positive battery cable...you should see a spark come from the end of the battery cable and the positive wire that came off the rectifier ...if you don't...try again!
After you get the "spark"  LOL
Stop the motor, re-hook up the positive wire to the rectifier, and start your motor, power should be as normal again.
Cheers
Brian

glort

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Re: Another alternator problem
« Reply #9 on: June 26, 2018, 05:01:37 AM »

Different to how I have always done it.  I wouldn't be waiting for the voltage to come up that high before disconnecting the battery!
Once the voltage gets up to 20V even it should climb on it's own and energise the field from there. If it didn't, I'd think something was wrong.
Connecting an escalating AC supply to a battery would not be something I would do. Unless I miss understand what you are doing, I'm a bit surprised the genny comes up at all. the load would have to be significant in the volage difference and the load that caused.

I can't see how you will smoke a rectifier feeding it DC either. It would be conducting full time rather than Cycling but for the time you would have it connected, wouldn't cause enough heat build up anyway.
I'd be far more worried about having a generator ramping up to 9x the rated voltage of a battery myself.

I thought the proper way to do it was with the genny not running. Give the thing a couple of liks and it shoul ramp up from there. I have done it many times with the genny turning but again, only a couple of licks till the thing comes up on it's own. Overspending the genny a bit usualy helps the voltage rise as well.


Johndoh

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Re: Another alternator problem
« Reply #10 on: June 26, 2018, 08:56:19 AM »
Thanks guys the generator is producing power now! Interestingly when I was trying to figure out what was wrong I watched a video by generator guru. In it she said you disconnect the wires from the brushes on the generator and you should get 4-5 volts from the terminals on the brushes. There was nothing there I assumed it was scrap. Thanks Top Eddee Glort it's now running producing a very steady 235 volts. Lesson learned - youtube videos aren't gospel!
« Last Edit: June 26, 2018, 12:17:59 PM by Johndoh »
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glort

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Re: Another alternator problem
« Reply #11 on: June 26, 2018, 09:27:03 AM »
Quote
Lesson learned - youtube videos aren't gospel!

I have seen  a number of videos where the information is just plain wrong to the point of ludicrous. I have pointed it out nicely and the creator has had a hissy fit and called me all sorts of names till 10 other people chimed and and said I was right and they were an idiot.

Like all other information, you have to try and compare it to other sources or test it for yourself.  In this case the latter didn't apply so well!  :0)

Main thing is you got it going.
I'm looking at a genset on fleabay now and have emailed the seller to see if the thing is functioning.  As against the ideal of this place, I don't really want another fixer upper right now, I have more than enough on my plate.  Just want something I can set up and enjoy.
Got the roid to balance before I take on any more engine projects as well as the IMAG I have just started on.

quinnbrian

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Re: Another alternator problem
« Reply #12 on: June 30, 2018, 01:38:19 AM »
Here is the ST manual I used to reflash my gen head...hope this helps...I didn't know you could reflash, when it wasn't running..have always done it this was...It's on the last page of the manual.
http://cgg1.com/index_htm_files/ST%20Manual-42013.pdf

38ac

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Re: Another alternator problem
« Reply #13 on: June 30, 2018, 01:56:10 AM »
Won't help you now  but a trick I learned to easily acomplished the  same thing is to simply  plug a single speed electric drill into the receptacle and with the engine running hold the trigger back and spin the drill chuck backwards.
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BruceM

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Re: Another alternator problem
« Reply #14 on: June 30, 2018, 03:34:35 AM »
I've read good reports on the drill method.  Makes sense- it's a brushed DC motor really and excitement of the mains windings will get the harmonic winding hopping too.  The hard part these days is finding one that isn't variable speed, which might not work.