help with genset 8/300

[stockers08]

hi all

i am in need of some advice regarding a repair to a genset 8/300 welder generator.

im not a welder, but it seams you guys might know more about these units.

the issue i am having is i have no output on anything. no dc, no 415 no 240.

i have tested the capacitors (fine) there are no burnt out coils in the stator. the only thing left is the diodes. but i cant seam to find them nore get the generator head off the engine to search deeper into the bowls to find them.

anyone ever replaced the diodes or separated the generator head? i have heard that genset are not worth contacting. so i wont

many thanks in advance guys

 

[penfold]

It might need the rotor flashed if it's sat unused for a long time and lost its magnetism.

 

[stockers08]

i tried flashing. no such luck. im thinking its the diodes on the armature. but i cant see nor get to them. i tried removing the back of the head, but it was jammed on there. does anyone know if the are normally a tight fit?

 

[penfold]

How is it held on? Is it cantilevered?

 

[stockers08]

there was 8 bolts holding the back plate on. these go into the iron block surrounding the windings. with these bolts removed, it would spin with alot of effort, but would not come away from the generator. it is the same and the engine end aswell. i removed these bolts aswell but again, no movement. i will add i did remove the long bolt going through the centre on the armature before attempting to remove the back end.

 

[penfold]

I'd suggest trying the same removal trick that works with smaller cheapnese gennys; tap the hole the long bolt goes into for a grease nipple or hydraulic fitting and get it off that way.

 

[stockers08]

im onnly trying to remove the stator to get access to the rotor. so i can test the diodes. i can solder them while still attached to the engine. but i just cant get at them currently because i cant get the stator out the way .

 

[Jim Davey]

Rotor will be connected to the crankshaft via a taper or a flex plate. The other end of the rotor will be supported by a bearing on the end of the stator housing. You need to pull the stator housing off first before you can release the rotor from the housing.

 

[Jim Davey]

Call Glyn at MPM Plant for any help you need.

 

[stockers08]

its onyl the stator i want off. the rotor can stay put. but i cant get the stator off. will heating the bearing plate make it easier to pull it off the bearing?

 

[Jim Davey]

A two legged puller would be better.

 

[stockers08]

hmm thinking im gonna have to get the engine/alternator out of the trailer first then. no fun

 

[Jim Davey]

Call MPM, there are tests you can perform with the engine and alternator in place before you get all medieval on it's ****.

 

[stockers08]

im confident it is the diodes at fault as the capacitors test fine, all stator coils test fine. that just leaves the diodes.

 

[Jim Davey]

That's definitely a rotor out job then.

 

[stockers08]

i should be able to de solder the old diodes in place. why would it need to come off when i can take the soldering iron to it.

 

[penfold]

Rotor will be connected to the crankshaft via a taper or a flex plate. The other end of the rotor will be supported by a bearing on the end of the stator housing. You need to pull the stator housing off first before you can release the rotor from the housing.

I can't see it being on a flexplate if it had a long bolt through the rotor; the bolt must screw into the end of the crank to hold the rotor onto a taper or taper and woodruff. I can't see how removing the casing and stator is going to be any less painful than shifting the rotor, plus it will be easier doing the diode job on the bench rather than bent over the chassis of the genny.

 

[stockers08]

ok, so i got the rotor off. and there is no coil, no diodes. nothing. just a cylindrical iron rotor. im guessing this makes it a permanent magnet generator.
i put a penny washer to it, but it did not stick. so not magnetic. would flashing re magnetize it?

 

[Jim Davey]

Are there slip rings?

 

[stockers08]

nope no slip rings. i should have taken a picture thinking about it. true, i did try flashing it. but only low current low voltage. 9v dc probably less than 1 amp. im now thinking car battery with a few hundred amp down the welder side stator coils (32v output)