Generac 7550 Generator


I've got a Generac Generator that has no power output. A friend who is a very good mechanic has looked at it and found that it has no power output from the plug that comes from the base of the generator. He measured 5 volts AC from ground to hot in the plug.
Inside the "cap" that fits over the base of the generator, he found a wire that was burnt in half that goes to a module of some sort. He said the module has several circuit boards and various electronic components.
He said he has no way of knowing the proper way to troubleshoot the module to see if it is the problem.
Can anyone tell me anything that would help with this?
Should I just take it to a reputable repair place now instead of doing more with my friends help?
He also checked all of the output points on the panel and found all the outlets good. The breakers are also good and the switch for the breakers tested good he said.
When the unit is running, he said it appears to be working fine mechanically. The motor is running very well and he said the generator is operating, but not outputting from the plug on the panel side of the module in question.
Thank you for any help you may be able to give.
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modules fail and are expensive, at least a few years ago when mine failed twice.
my best friend a electrical engineer tossed the module and added a heavy duty switch. start generator normally, once its running stable with no power out you push button, it excites generator, like a start switch. you only hold it a very short time or you will burn out the start windings. has worked fine since.
modules must be a big profit item for generac no drawings or board parts availble, one big secret. $$$$:(
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wrote:

Thank you very much for your reply. I have a couple more questions for you if you would be so kind as to inform me:
Can you tell me exactly how to have the switch made? I have a friend who is an electronics tech, and he can make it and install it if he knew what to do. If a schematic of the installation is available from your friend, I would be in your debt. I could post a disposable email address for you to send it to.
Secondly, how much did the module cost that you replaced and how much labor did they charge you. I have to get this thing working. I live in the heart of hurricane areas in Florida. Hehe, the fishing is great.
Again, thank you very much for your time and information.
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They wanted at the time 75 bucks for the module and 150 to service the generator. So I had them do it.
on its second use the module blew again:(
my buddy came to my rescue..... I dont need the generator often will ask him tomorrow for a wiring drawing, the momentary contact switch is heavy duty but nothing special, t the time he said it connects the start winding, which excites the generator. you push it justy long enough to hear engine speed drop a little which means its generating.
will see him monday. glad to be of help
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wrote:

what about their repair warranty? How long a time passed between the repair and the failure? Maybe an email to the company might get you another generator to replace your "lemon".

I wonder if the module PCBs are servicable separately? A good tech might be able to find what failed,and perhaps suggest an improvement. Do you still have the old module,or did the service center keep it?(maybe THEY repaired the failed part in the original module??)
--
Jim Yanik
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wrote:

Were you able to contact your friend? I've taken my generator to a shop for repair. They tell me I'll have it back towards the end of this coming week.
If I were to have a schematic for what your friend did, perhaps I could use it next time.
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he found a intermittent open start winding, patched that and installed the switch.
The board is potted in plastic and no schematics are available.
when I heard what he did I knew it didnt lend itself well to explaining on the net. hopefully the service folks will get it working well, but try it a ferw times before you put it in storage so you will know its working.
mine worked great, tried it once, put in storage, 3 day outage is when I found it dead.
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<snip>

Generators of this type are self-exciting. This means some of the output of the generator is rectified (converted to DC) and used to provide the magnetic field that the generator uses to generate electricity.
This leads to a chicken and egg situation. The generator must be generating power to provide the magnetic field it needs to generate power.
The reason this works is due to some residual magnetic field that remains in the iron when the generator is off. This is enough to get things going when you start the generator. But...there are a few things than can cause problems. One is time. If the generator is not run for a long time, the residual field can decay to the point where you will get no power output when you start it. Most manufacturers recommend running the generator for a short while every few weeks. That will prevent this.
Now, your generator probably uses a brushless alternator, which complicates the situation somewhat, but the basic principle still applies. You need a little residual magnetism, in the right places and with the right orientation, to get things going. I can believe a problem with the control board, which would be handling commutation of the brushless alternator, Could mess this up.
So the story you got is at least feasible....
HTH,
Paul
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wrote:

Yes, it did help Paul. Thank you for your explanation. Now I have to find out exactly how to do this myself. If hooking up a DC power supply to the "slip rings" is all it takes to resolve this, then I'll have to learn how to do this properly.
Are there any publications/instructions/diagrams you're aware of that would help me understand this in a practical sense?
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On 7 May 2007 07:48:20 -0700, "John Q. Public II"

DAGS for "flashing a generator" lot of info out there.
Also, there is a person selling a modified flashlight on Ebay setup to restore the magnetic field. Search for "Generator repair generac"
It comes with a CD with some additional info.
I have no experience with it and have no idea if it works.
HTH,
Paul
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wrote:

Thank you Paul. I'll check it out. If it's not too expencive, I'll buy one just to see what makes it tick. What does the expression "DAGS" mean? I've never seen it. The process of re-aligning the magnetic field is called "Flashing"?
Thanks again!
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"do a Google search".
I've never seen it used before,either.
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Jim Yanik
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On 9 May 2007 05:16:34 -0700, "John Q. Public II"

DAGS == Do A Google Search
Sorry, I forget which acronyms are widely used on which groups...
Yes, the common term for restoring the residual magnetic field is "flashing"
Paul
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wrote:

Hahaha, and I'm a programmer...
Now that's funny!
Thanks again man. You've helped me quite a bit.
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I was able to find a huge (300+ page) tech service and trouble shooting manual for my Generac on their website as a pdf. It very comprehensively describes all diagnostic and service procedures. Perhaps they have one for the 7550 as well.
Smarty

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Thanks "Smarty". I'll check to see if they have any material on mine.

message
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