OT - Need some help

[medic29]

I know this is off topic, but it is kind of reef related. I've got a generator that I plan to use to power my reef setup in the event of a power outage.....well, currently it is not putting out the voltage it should. Anyone who could help me figure out why and/or that might be familar how the generator head works??

[GuySmilie]

What should it be putting out and what is it putting out?
On most generators the voltage is a function of the motors rpm.
Motor speed is typically controlled by a mechanical governor on the fuel delivery device, or by electronic control.

[UH_OH_5_OH]

You might want to throw this question into the DIY forum as well.....I'm sure there must be one or two electricians or mechanics that keep saltwater fish in there ! LOL !

[medic29]

The voltage it is putting out is 11-14v AC and it should be 120v AC. Motor RPMs is not the issue...I know that much. It has something to do with the generator head. There is some rust on the inside of the outer coil. I can't see the outside of the inner coil. I'm thinking there if there is rust in there it would degrade the voltage, I'm just not sure as I don't have a lot of electronic experience; I have more mechanical experience.

[BeanAnimal]

It sounds like the genhead is shot. Where are you testing the voltate at? Can you get a reading right off the coil leads? Please be careful, you can get whacked pretty darn hard (or worse).

What do you get from the ground lug to each leg? With the genset off, what resistance do you measure across the legs? To ground from each leg?

The rust could have shorted the poles of the head. It could have eaten away one of the connectors, etc.

What size genset is it? Is it just 120V or 220V output? (If it is 220V, there will be (2) sets of windings to measure.

[medic29]

Could this be the voltage regulator being bad on it? I've heard of several instances of them going bad on generators.

[BeanAnimal]

It could be... that is why you want to check the output at the poles.

[medic29]

I'll try to do that in the next day or so. No can I do this from the connectors from the coil (there is a multi-wire conncetor where the voltage regulator and outlets connect to the gen-head - can I just test using these contacts?), or do I have to actually get in to the coil? - I could take a pic of what I'm talking about if that would help?

[BeanAnimal]

Photos would help.

You want to first measure the input side of the vreg. You also want to check for shorts between poles and from the poles to ground... DO THAT with the power off.

[medic29]

I'll get some photos taken probably in the morning and get them posted and let you know what I find out checking the continuity/ohms.

[RV8tor]

Before you replace anything, you may want to FLASH the field. I don't mean that in a dirty way either. When a generator sits and doesn't get used you can loose the field. Meaning the magnetic field. One easy way to do this is to plug in a power drill into the 110 v, start you generator, pull the trigger on the drill and hand spin the head on the drill while holding the trigger down, this puts a charge from the motor of the drill to the field of the generator and will regenerate it for you. You will know instantly if this works because your drill will spin up so be careful. IF that doesn't work then you may have a bad part. This happened to mine during the 6 days I was without power last November. I wouldn't mess with the coil at all, take it to a shop that knows what they are doing. there is one in Bloomington, but I am sure you can check the internet for a recommended service department for your generator. To prevent this from happening in the future, anytime you go by the generator just pull the starting rope one will do. keeping the field generated. hope that helps

[BeanAnimal]

Yeah I did not want to get into lost or reversed fields... I figured we better have a look at the ouput first

We picked up a very large diesel welder because it "didn't work". It just needed polarized I usually just use a 12V car battery and load the coil momentarily.

[medic29]

Well, I've got some information, but I'm not sure it is what I was hoping to find. I did take some pics today and here are some:



I took the plugs out of the outlets; these plugs is what supply power to the AC & DC outlets.

I checked for continuity between the tabs in each outlet on the Gen Head and a ground. None of the tabs (connected to the coils inside the Gen Head) had any continuity with the ground, so I have to assume there is no ground short. I had also checked for continuity between the other leads as well; the results were none.

I left the plugs unplugged from the gen head and started the motor. With the motor running at fairly high RPMs I checked the voltage from the 12v tab on the gen head and got the same as what I did from the front of the generator. I then checked each of the 110v lead tabs and found it was generating 4.3v AC when checking the 110v lead tab and the com lead tab. These all are from the tabs of the Red outlet. All of the wires from the White outlet/plug go into the voltage regulator, then out to the various outlets on the front of the generator. See the drawing below.


I'm not sure if there is any other testing I can do without dissassembling the generator head.

While the generator was running I took a drill and plugged it into the generator and tried turning the end while depressing the switch as was suggested. I was not able to turn it very quickly, actually fairly slow. I don't know if it needed to be turned quickly or not.

Okay, any other ideas or does this give you guys the info you were looking for or did I not do something correctly??

Thanks for your input!!

[GuySmilie]

Originally posted by medic29
Could this be the voltage regulator being bad on it? I've heard of several instances of them going bad on generators.

It very well could be. I used to work on a lot of generators in my old job and when the output would drop to ~12V AC, many time it was due to a faulty triac on the control circuit. I've got some old service manuals on disc boxed up somewhere. We mainly had Onans, Generacs, and a few Whites at our network locations. What make and model you got? If I can find the discs for your unit you're welcome to them.

[GuySmilie]

Whoops! Looks like you got a Generac
Looks to be a smaller unit <5kW.

All our stuff was 20, 30, 50, and 100kW. Even though a lot of the Generac boards were interchangeable between their different size gensets, the diagrams I would have would not reflect what you're working with. Sorry!

Edit: Looking closer at your pix, that unit has not been well maintained. I see a lot of corroded wire connections, especially that spade connector in the second picture. Corroded terminations such as those could easily be causing your trouble. Before you get too far into it, I'd get after that corrosion on all the connectors with some electronic contact cleaner and a small wire brush. You may be surprised. Also, look for obviously distressed components on the circuit boards. Triacs can show burn signs on their connections/wiring when they fail. Also check electrolytic caps for blown ports. If you know how to use a DMM, check all your diodes for forward/reverse conduction. Good luck.

[medic29]

It is a Generac 5k watt

[newreefer2]

I use to work at Floyd Electric in Champaign ( many many years ago) They did all the motor and generator repair work for Chanute AFB and a lot of generator. They used to be very helpful with giving advise prior to taking work in.

[medic29]

Floyd electric is no longer around.....

[cioutlaw]

Originally posted by medic29
Floyd electric is no longer around.....

Nope, but they were good people. Dont find shops like that anymore.

[pokerfish420]

Its a long shot but did you try sammys auto electric? he rebuild all types of stuff. Not just car stuff.