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Winco generator runs but doesn't generate

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Posted by Nick Danger on August 23, 2009, 1:57 am

Posted this at alt.home.repair, and someone suggested this is the better
place to post

Looking for generator repair advice...
I have a Winco 900-watt Tri-Fuel generator with about 320 hours on it for
home standby use. It's worked well for years - it easily powers everything
in the house except the central AC. During a power outage last night, after
it had been running for about five hours, I turned on the basement light
switch, the lights flashed momentarily and then went out. The only other
load in the basement is a dehumidifier that I always keep running when on
generator power as it helps stabilize the output. I then found that the
breaker for the basement had tripped. We've been in the house over 20 years
and I've never seen that breaker trip. I reset the breaker and then the
entire house went dark. The generator kept right on running with no
noticeable change in sound (i.e. it didn't sound like it was working harder
or easing up). I tried resetting the breakers on the generator, plugged a
light into the outlets on the generator panel - but nothing worked. I turned
it off for a while to see if maybe the problem was heat-related. Still no
luck. It starts up just fine but produces no power. It seems unlikely that
the problem would be a loss of residual magnetism. It gets exercised
regularly, and it was running for five hours when it failed. Does anyone
have any suggestions for things to look for?

btw: After the main power came on, I turned on the breaker for the basement
and everything functioned normally.


Posted by Ulysses on August 23, 2009, 3:09 pm


That's a rather small generator for running a whole house!  I'd start by
looking for any obvious bad connections going to the AC receptacles on the
genny, then check the circuit breaker(s) for continuity.  There may or may
not be a fuse inside the genny and if there is it may be for DC output,
assuming you have that.  Next I would check the stator and rotor coils for
any signs of over-heating and possible bad wires.  Check the ON/OFF switch
for continuity but that would probably only prevent the engine from running
if it was shorted.  There is probably a bridge rectifier inside so I would
check that too--there should be continuity one way and not the other on any
and all adjacent connections and none should be connected to the rectifier
case.  Next I would test the diodes on the rotor assuming this is a
brushless design.  My guess is that it's either a bad circuit breaker or a
bad diode which was caused by an overload.  Also there's probably a
capacitor somewhere (could be located just about anywhere) but I would
expect a low output rather than no output if it was bad.

Posted by Nick Danger on August 23, 2009, 3:44 pm

My bad - I meant 9000 watts. It's been a rough week.
If there's a bad  breaker somewhere, then it's hidden from view. The
generator has a couple 120-volt outlets (one on each leg of output), a
240-volt outlet (I don't have anything I can test with that), and a big
twist-lock that connects to the cable that goes to the transfer switch.
There are only two breaker switches on the external panel of the generator,
and I reset those multiple times. There are no other breakers between there
and the main panel. Since everything in the house came on normally when the
main power returned, I don't see where there could be any problem in the
breaker box.

I've done some minor repairs on the engine side of the generator. It's easy
to find parts through Google - usually on eBay. But when I look up part
numbers on the generator side, I don't see anything. I'm not afraid to do my
own repairs but I want to know that the part I'm replacing really is bad.
Else, the expenses could add up really quickly. Part of me wants to see the
unit declared unfixable so I can buy a newer bigger one that can drive the
central A/C, since the really big storms always seem to occur on the hottest
humidest night of the year. But the other part of me has to contend with the
economic conditions of 2009 and is a lot more interested in the DIY option.

Posted by vaughn on August 23, 2009, 5:53 pm

   Go to Home Depot or Ace Hardware, ETC. and get yourself a cheap neon
tester.  They are usually good for 120 or 240, so you can test all three
outlets with it.  Then do everything that Ulysses said, plus if your
generator has slip rings, make sure they are clean and that the brushes are
free in their holders and still long enough to make good contact

     Bigger is not always better.  Big generators use lots of fuel, even if
they are lightly loaded.  Where I live, electrical outages can run into the
weeks, so my "whole house" generator is only 4 KW.  We just practice load

   That is why we keep a spare $00.00 window unit for our bedroom.  I can
install it in five minutes.  It is small enough so that the generator can
easily run it, and we have it as a backup in case our central AC breaks.
Much cheaper tha having a huge generator!

You and me both!  Plus I find myself coping with retirement (or joblessness,
whatever you want to call it).


Posted by Martin Riddle on August 23, 2009, 10:55 pm

Sorry for top posting...

Since its 240v and neither phase works, I would look at the field
connections, the diode bridge, and the exciter transformer if it has

But it could be that the common of the 240v is disconnected, for some
reason. Leading to no output.

I would pop the screws and look inside, it may be visually apparent what
is wrong.

If the lights Flickered, then there was an intermittent connection which
might be easy to spot.
With the vibration, you'd be lucky to find a nut fell off somewhere.


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