Re: HELP! Onan Emerald III No AC


"QBall" <qNOacyoung@xxxxxxxxx> wrote in message
news:mQkei.213304$Fk2.5970@xxxxxxxxxxxxxxx
Alan,

I was able to do the checks as you said. Here is the strange part that
totally loses me.
I charged the battery, it took awhile because I have been doing it in
between the periods of rain that have almost been constant the last
several days. When I started it the first time it would start, run for
about 20 seconds and then blow the DC fuse. Then if I would try to start
it again it would go back to the slow start problem. I disconnected one of
the brushes and it made no difference, still slow start.
I came back to it the next day and the issue was exactly the same. It
started and blew the fuse the first time and then went to the slow start.
I pulled one of the brushes and started with the main breakers off, still
slow start. Detached both brushes and turned the main breakers on and it
started and stayed running even when I released the start button. I let it
run for a few minutes and then stopped it and reconnected the brushes. I
restarted it after several minutes and it started again. I ran through
several cycles of start and stop and it started everytime. It does not
stop when I release the start button. It is now only putting out ~2VAC.
While it was running I did check the terminals on the back of the electric
choke and had minimal voltage not near 36vac.
Any ideas from here or should I just take it in to be looked at? Thanks
again for your patience and assistance.

Quentin


Since it will stay running with no output, you -definitely- have problems
with the control board - from the symptoms, most likely the contacts of K2
have welded together (K2 is energized by the battery charge windings, so the
contacts welding together would make it think it -has- output. You may still
have other issues, but with some jumper leads we can simulate what the
control board does, and check most everything else.

You'll need two jumper leads with alligator clips on both ends, and a third
jumper lead with a 5A fuse and a diode spliced in series in the middle of
it - a 3A/200V diode from radio shack will work fine. Remove the control
panel - the control circuit board is mounted to the back of it. Carefully
work the connector loose from the circuit board and unplug it. Make sure
that you have the brush leads hooked back up in the generator housing.
Follow the two leads from the ignition coil - one will go to the control
box, the other goes to the points/condensor. In the control box, find the
starter solenoid - cable from battery will go to one large terminal, cable
from other large terminal goes under genset housing to starter, small
terminal has lead going to pin 2 of the control board connector. Hook one
jumper lead from the battery terminal at the solenoid to the control box
terminal of the ignition coil - this should give you ignition and fuel pump.
Hook second jumper lead to battery terminal at starter solenoid, and touch
the other end of this jumper to small terminal of starter solenoid - genset
should crank and (hopefully) start. Disconnect this jumper once genset is
running.

Ok - now we've got the genset started and running. Now we need to flash the
field (use 12v from the battery to briefly provide power to the brushes -
this provides an initial output, some of which is used to provide more power
to the brushes, which gives more output, round and round until output is
about 120v ac and dc voltage at brushes is about 30-35v dc. Find bridge
rectifier CR4 mounted in the back bottom of the control box - looks like
either a miniature hockey puck or like 1/2 of a domino, with 4 terminals -
one of these terminals ( the + terminal) will have a lead going to pin 5 of
the control board connector. Connect one end of the jumper lead that has the
diode and fuse in series to this + terminal...use the end of the jumper lead
connected to the end of the diode that has a band on it. With the genset
started and running, briefly (like for one or two seconds) touch the -other-
end of this jumper lead to the battery terminal at the starter solenoid. If
everything is ok, you should now have approximately 120v ac output from the
genset. And you should see 18-26V ac at the choke terminals (sorry about the
36v figure - that was from memory the other night, but this genset is a
little less than the one I was thinking of).

If all this worked ok, then it would appear all you need is a new control
board. If the genset started and ran ok with the jumpers, but you didn't get
120v after the field flash, let me know what voltage you do get - if voltage
is very low, let me know what voltage you see on the output while the field
flash is hooked up.

Alan


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