Brushless Generator advice. Devilbiss GB5010-1

[dacflyer]

i been beating my brains out on a generator i been working on for a few weeks now.
i have checked all there is to check, and i still cannot get it to put out.

here is what i have found and done to repair.
1st of all the cap was bad, i replaced it..then i replaced the diode on the rotor that was also bad.
all the windings check out ok, and the rotor checks out ok. this is a brushless design.
i have tried to induce voltage in several ways to try to excite the generator to no avail.
i have induced AC and DC to the cap windings, and have tried the output windings as well, seems nothing is working to get the rotor excited.
is anyone here have any tips that i have not tried already.

[Lenp]

Hi,
It's important to know if this was a unit that just failed or is it one that 'Uncle Bob' worked on and couldn't fix?
Were the replaced cap and diode Open or shorted?
Do you have a complete schematic? I saw your posts on SmokStak and it seems there are some issues with the drawings.
I good drawing would be of help
Len

[dacflyer]

that was the only drawing i was able to find for it..
the diode tested ok with a meter, but fail with a load test..
the cap was bad ( case split open from friction / abrasion. it was not strapped down good.)

i bought this as a fixxer upper, but not sure if anyone ever worked on it before.
it has a new cap (supposed to be 35uF @ 350V ) and the diode is new and a exact replacement.

[dacflyer]

finally finally found the damn problem !
http://www.smokstak.com/forum/showthrea ... 755&page=2
it took a while, but i persisted, and found the problem.. read on the thread.

[dacflyer]

ok,, i sort of repaired the rotor on this thing. i reassembled the generator, fired it up, and it works now,,but i still see sparks (carbon trail burn ) in the rotor when a load is turned on. so i shut things down. i have to decide what is cheaper..to try to get it rewound, or find a new gen. head for it.

[Lenp]

If you can see the tracks could you clean them out, maybe with a Dremel then repair the area with epoxy. I had a DC motor commutator with carbon tracks between segments. I fixed it that way, cleaned up the commutator and many years later it is still running.

[dacflyer]

if i feel the enthusiasm, i may unwind the rotor again and maybe a bit more, the insulator material was carbon tracked, i fixed the copper after i unwound it to that point, and i then put tape over the insulator, rewound the copper back onto the rotor. put the head back together, tested it,, i came back to life YAY. but when i applied a heavy load, i saw the rotor spark again. but it only sparked a second, and maybe again when i reapplied a heavy load,, but it still put out just fine.
i had up to a 4.5Kw load on it. 240v
still sparked from the same area as before, so i am not sure if there is a bad spot deeper in the rotor arcing to ground or not.

[Janitor Tzap]

I'd say just replace the Rotor.

But, at $1000 for a replacement rotor, you can buy a new Generator for less.

This Generator is 18 years old, right?
If it has been used a lot since then, it would make sense that the Lacquer coating is breaking down on the wires.

I can see only three options.

#1) Find a Generator repair Shop that will put new wire on the Rotor.

#2) Rewind the Rotor yourself with new wire.

#3) Unwind the current wire and re-coat it with Lacquer, then rewind the Rotor with it.
{This last one I don't recommended, because the copper wire is old, and will probably break down after only a few uses of the Generator.}


Signed: Janitor Tzap

[dacflyer]

as far as i know, no replacement rotors are available.
i may try my luck at rewinding it. i would only be out the cost of copper wire.
or use it as is, til it dies, and then search for another complete head.

[dacflyer]

UPDATE >> i removed the rotor the other day and did another megger test on it...it failed, but the failure point was deeper down in the armature.
so i decided to unwind and replace the copper with all new..only 1 side of the rotor is bad, so i will only rewind the one side. i unwound 215 turns ( 225ft. of copper ) looks to be 16-17Ga. wire
there is 1 motor shop still here. the other one went out of business. so i'll be going by there later on to see how much the copper will cost me.

stay tuned

[dacflyer]

update >> went to motor shop and got the copper today. the wire is actually a 17Ga.
i got 235ft of it, cost me $14.00.
will try my luck to wind it in the next few days...

[dacflyer]

UPDATE >>> well i finally got the damn thing rewound
i made sure the new coil was load balanced.
( i applied 70 volts and got 6 amp load on the good coil,
and made sure i had same load on the new coil., both coils are about 2.4 ohms )
all i have to do not is get some varnish to lock the coils in place.
it was hard as hell to get it all perfectly wound.
i'll post pix of it soon..

i guess when i get the varnish, i should just add in a little at a time to let it sink into the coils.
let it dry some, and then add more.??

tips ???

[Lenp]

Most motor shops dip the coils then bake them. That may or may no be practical!

[dacflyer]

ya, i am sure they dip them before they are all assembled..unfortunately mine is..

any suggestions as to what type of varnish to use ?

i am guessing baking it helps it dry faster ?

[Lenp]

Baking also dries out the windings and probably causes the varnish to thicken rather than run out after dipping. Google motor varnish, there is plenty of information. What about the shop where you got the wire?