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Discussion Starter · #1 ·
i got a generator in for service. let me first state i haven't done small engines generators in like five years so its been awhile. so here is how the story went down. customers complaint was that the generator was smoking after start up. well come to find out they had only used the machine once and then stored it for like three years. so first thing i check is the oil which was gas. so i drain the gassy oil and carb put fresh fuel in it and new oil to get it to run so i can verify the smoke goes away after it burns all the excess fuel out of the engine/oil and i want to check the output before i qoute the customer on flushing the fuel system and replacing the carb. i get it running smoking stops and i go to test the output and it has nothing. so first thing i do before even grabbing my dvom to test voltage is grab a jumper wire and flash the field. its been sitting for three years so im like yeah the rotor probably lost residual magnetism. flashed the field and boom all circuits have power. load tested them everything works. so yesterday i get the new carb put it on get it running. just for giggles i check the output again. fail no go. so im like hmmm it sat for two weeks and the rotor lost magnetism again. im thinking ive never seen this before something in the brush circuit must be shorted to ground. so flash the field again and boom it has output. shut the engine off and try to restart and the generator is dead again. heres the catch. the generator is not loosing magnetism i have 2-3 volts ac output after restart which means that the rotor is energized. so im like well this sucks. so i grab my books for generators which are outdated at best and im trying to find resistance values and an applicable chart for this gen but its too new. so i try and trouble shoot it any ways. so first thing i do is check rotor resistance i think was 8 ohms. check for short to ground and that is fine. i take out voltage regulator hook up battery up to brushes and record voltages out of dpe/main wires and 11/22. dpe 2/6 was like 180volts and the rest of the main wires are 110v. rpm is 3850 no load. so this tells me the stator and rotor should theoretically be fine. so i think it is the voltage regulator internally bad not being able to take the low input voltage from the dpe windings during start up and increase the dc voltage into the rotor. has anyone had this happen before?? so im thinking this is single board regulation but it has a bonus part ive never seen before and isnt in the parts diagram. it comes from wires 11/22 and is inline with those wires and plugs into the voltage regulator. it is a piece like 2 inches long and 1 inch wide covered in heat shrink and has two terminals in and two out. it looks like it has a relay and a step up transformer. i dont know what it does. so i took this device out of the system and i hooked the 11/22 wires straight to the voltage regulator and retested the generator and nothing changed. how i was thinking of testing the voltage regulator was to get a potentiometer and take 120ac and bring it down to like like 2-3volts and increase it slowly while watching for a increase in voltage on the dc side of the board. will this work?? i duno i have no repair manual for this and besides checking for stator winding resistance and short to grounds in the stator windings i dont know what else to do. if the rotor had a a rolling short it shouldnt have good out put on the startor windings while running right?? i just dont want to throw a volatege regulator on this unless im 100% thanks for helping~!!
 

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Discussion Starter · #2 ·
found it

the problem was a bonus piece connected to the voltage regulator which in essence is a capacitor that excites the voltage regulator. the voltage regulator needs 12 volts to be turned on or else no out put would occur. briggs and stratton has discontinued the "field boost assembly" and updated the generator for a new voltage regulator assembly thats like 80 bucks and does not need 12 volts to be excited. so instead of buying this i ran a fused jumper wire to the + brush lead with a momentary switch inline to Flash the regulator when the generator is running. this saved the customer money the only downside to this hackery is that the battery must be charged or else it will not excite the existing regulator.
 

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Jerry rigging might be ok for something I was doing for myself but I sure would not send it out of the shop wired like that. Huge liability issues in the event of an electrical shock or fire.
 
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