1990 Prevost 50DN alternator issues...

[Timkar]

1990 Prevost charging issue. 50 DN Alternator not charging, 24V system.
When running alternator has 24V (battery voltage) on main lug which is also connected to F1. F2 has 0 volts (field neg) and the relay connection has 0 volts. On the voltage regulator connection results are battery is 24V, ignition is 24V and field is15.2 volts. Suspected the blower cut in relay (R4) and checked it. There are 3 terminals with wires out of 4 available. Term 1 has 0v, term 2 has no conections, term 3 has 24V, term 4 has 0v.
Thinking of applying separate 24V to the relay terminal to see if it is in wiring, relay, etc.
This coach has not run for a couple of years and just put a different 8V92 in to it...
Anyone out there with this era of Prevost that can check their cut in relay and regulator voltages? I checked on my 95, but totally different wiring...TIA

[luvrbus]

Tim, take the serial number and call Prevost they will have the schematics for that bus Prevost changed that sh** every 6 months,15v on the field is a little high it should read 12.8 and if it is magnetize it should be charging.You know if the batteries are fully charged and you leave a charger connected they won't show charging     

[Timkar]

Will try Prevost tomorrow if can't figure out today. Relay should be 12V(nom) with a 24V 50DN alternator? Juts have to check before I try from external source.
No charger connected. Thanks...

[Timkar]

Grounded F2 no change, put 24V to relay and tell tale disappeared but not charging. Changed regulator and vanner. No changes, so I guess it's time to replace alternator...maybe in the spring as have to get Eagle ready to travel..

[Jon]

Assuming it is a 24V alternator, connect your voltmeter to the 24 post on the batteries and jumper 24 volts to the field terminal. If the voltage jumps up and shows charging it is the regulator, not the alternator. If no charging it is the alternator. No wiring diagram needed, just that simple test. BTW, if the voltage jumps to show charging disconnect the jumper to the field terminal because the alternator will have unregulated charging and it could get to an over voltage condition fast.

[Timkar]

When I try to put 24V on the F2 terminal it sparks like there is a short to ground...

[Jon]

Same thing if you run the jumper to the field terminal on the regulator?

[luvrbus]

Tim, you have a bad diode you can check those with a meter

[Timkar]

Thanks guys. Will remove this old gear driven unit in the spring as it is getting cool and need to get the Eagle ready to go...

[luvrbus]

Stop by the house going or coming Tim and I will give you some Prevost manuals lol I need to down size on manuals

[Timkar]

Will try. Are you going to be home next week or are you heading "east"? If not then we wil see you in Q

[luvrbus]

I am sure we will head east I have a 8v92 I just finished and dynoed I need to deliver to Ft Smith Ar just waiting on 1 part for it 

[daddysgirl]

Well, just head east...straight to Virginia I'm less than 50 min. from the ocean...

[luvrbus]

New Orleans is as far east as I go only go there for the food 

[daddysgirl]

I"LL COOK!!!!
Ha...I can make you Cajun cuisine... with a side of 40w and grease that's forever under my nails?