MEP-804a wont turn off

[zipposrule]

I picked up an MEP-804a last week and have started bringing it back to life, ive gotten it running (and it would shutdown via the start switch no issues) but the alternator wasnt charging, according to the TM it had been wired backwards so i got that hooked up right and she sharted charging to my delight! but i went to turn it off and nothing, i was wondering if anyone had run into anything similar, im still pouring over the TMs but i have not found anything yet. anything else i should know about these generators?

 

[zipposrule]

 

[zipposrule]

 

[Guyfang]

All you have done is rewire the 24 volt alternator? NOTHING else?

 

[zipposrule]

All you have done is rewire the 24 volt alternator? NOTHING else?

before rewiring the 24v alternator (and having this issue) i reattached the wires for the aux transfer pump (were just pulled out of the plug, and also attached wire 125a back to the starter side of the starter solenoid where wiring diagram said it went. again the generator started and ran and shut off until i messed with the alternator.

 

[Guyfang]

Here is an old hard rule. "If it worked, and you did something to it. And then it doesn't work. Put it back the way you started from. Work now?" Try that. See if you can reproduce the original problem, no charging. And the set starts and stops right. Then you KNOW, its what you did, and NOT a problem that was lurking there and you had not seen it before.

Whats the date, and change # on the TM you are using?

 

[zipposrule]

Here is an old hard rule. "If it worked, and you did something to it. And then it doesn't work. Put it back the way you started from. Work now?" Try that. See if you can reproduce the original problem, no charging. And the set starts and stops right. Then you KNOW, its what you did, and NOT a problem that was lurking there and you had not seen it before.

Whats the date, and change # on the TM you are using?

yes i know that rule, just figured id ask for help if i was overlooking something simple just due to not being familar with these units! the TMs i am using are from green mountain generators, and all seem to be dated 2008+, one is 2008, one is 2011 and one is 2010. i will start swapping stuff back around today. I just managed to ruin some of the threads on the lunette ring and completely ruin the nut for it attempted to get that flipped on the trailer, the nut looks fun to find after looking around alittle bit

TM 9-6115-643-24
TM 9-6115-643-10
TM 9-2815-254-24
TM 9-6115-643-24P

 

[zipposrule]

okay ive got everything hooked up as its supposed to be (as i originally pictured it) except the 248a wire is disconnected, now the generator charges and starts and turns off normally, as far as i can trace that wire ends up at CR-6 and i am unsure where or what it does from there or what the diode does or where that CR-6 diode is located!

 

[zipposrule]

so after all the tracing, it appears to me that the 248 wire takes power from s1 back to the alternator to excite it? but its still making voltage without it hooked up? it appears the hiatchi lr220-24 alternator is internally regulated but not regulating (outputting 32-33 volts) so i am hoping this is my issue with shutting down? when i turn s1 to prime and run i have power at my 248 wire, is this needed to excite and regulate voltage? when i turn s1 to off there is no power on the 248 wire but i am assuming when it is running there is power supplied to the terminal on the alternator until i disconnect it and it will shut down, so i suppose i answered my own question but i hope this helps someone in the future!

 

[zipposrule]

i dropped my alternator off at the alternator shop today and after testing and evaluating it and i explained what was going on he believes that i burnt a diode somewhere. I am thinking the cr-6 diode in the charging circuit but i am not sure where it is physically located on my genset. my alternator was also only putting out 6amps according to his test. on my ampmeter on my generator it was putting out 20amps but was also over charging to 32-33 volts. he was going to open up the alternator today or tomorrow and see what was going on with it further.

 

[Guyfang]

Everything is in the alternator.

 

[zipposrule]

I also found cr-6 diode bad tonight, presumably got fried when alternator got hooked up backwards

 

[Guyfang]

That will do it.