Slip Ring Cleaning

[Ken1]

For those of you who have an old (1986 Onan Generator) which is not producing any 120V this was my solution.  My symptom were the unit would start and run while holding the start button in and stop when released.  After reading the manual downloaded from hear I checked the output and found low or erratic output.  In my case this was caused by black and dirty slip rings or stuck brushes. I removed the brushes and cleaned the slip rings as directed in the manual except I used fine emery paper stapled over the end of a square wooden stick since I don't have the stone referenced to in the manual and rather than do the jump connections I just cranked it over with the starter. when finished it put out 120V and ran fine. I was considering replacing the circuit board and other expensive or complicated options before trying this. Hope this might work for others as well.

[Stripe]

Thanks for the heads up! 

[legomybago]

Im curious as to how not having 120v output would not let the engine run unless you hold the engine start button in/on? Does 120v's produced by the genny tell a circuit board relay to open/close so it keeps running? Somebody hold my hand lol

[Stripe]

I believe on a lot of these generators the generator side acts as a alternator and returns electric to the ignition via a built in inverter. On some models the generator side is also the starter motor.
If the gen does not produce enough voltage to power the inverter, then you won't get a spark and well, you know the rest..

[legomybago]

Oh..... i??

[M & J]

Right or wrong it sounds good eh?

[legomybago]

The reason the genny ran must be because of the 12v coming from the start battery while you have the switch in the depressed position allowing the run circuit to be open...That one would take some time to figure out I suppose W%

Good job Stripe
and Ken
and oldrock

[DaveVA78Chieftain]

Once started, generators typically have a DC output used to provide the run voltage as well as recharge the battery to restore the juice used to start the generator.  Part of why there are so many relays in a generator.

Dave

[Ken1]

It is all explained in the Downloadable manual as to why the motor ignition is cut if not charging. It is all handled on the circuit board. I have forgotten the details, suffice to say that is the way it is, which is why I almost ordered a new circuit board before discovering the erratic voltage output.

[Froggy1936]

The correct color for any copper segment or ring is a chocolate brown and not very shiney Do not try to keep it a bright copper color As that just wears away the copper    Frank

[Ken1]

I agree Frank. One should not expect them to be bright copper colored however mine were black a light cleaning with fine emery got the system working again assuming it was not a stuck brush.

[Froggy1936]

Stuck or sticky brushes will discolor the copper. First (only if there is a problem) Make shure brushes are free, use a lot of caution, if working on a generator Reddy Killawatt can hurt you with high voltage a mistake can be your last one !  A quick evaporating cleaner can be used with compressed air to blow away excess( SPRAY ELECTRICAL CLEANER) After cleaning and brushes are free, copper can be polished with a very fine emery or a special stone, wile the unit is running. Again be extremly cautious try application of device used to clean wile unit is not running to make shure it will work after started. Dont get carried away with cleaning, before,during or after  If you do not feel confident with working with 220V elec have someone else do it preferably an electrician    Better safe than sorry  Frank

[Ken1]

Thanks Frank for the high voltage  one must be very careful working with 220V as well as spinning parts. I agree if you are not competent leave it to those who are.