voltage drop

chazwood · June 21, 2013, 03:16:14 PM

Could there be anything, besides the 50dn alternator dropping a leg of the stator, that would account for a voltage drop of 4 volts (27 down to 23 with no big load) on my dash meter?
I'm hoping it's a relay or fuse or something that costs less than a new 50dn.
Hey, i can always dream.
We were coming back from a concert in MN, (going home to Al.) and about Chicago, my voltage dropped about three volts. We made it home without lights or air and it held steady at 23vlts (as long as you didn't hit the air cond.)

Is my 50dn toast?
or could something else cause this?

Dave5Cs · June 21, 2013, 03:41:34 PM

Bad Voltage regulator or a bad gauge. I am just trying to help ya out on the cost thing.

Dave5Cs

chazwood · June 21, 2013, 03:47:06 PM

luvrbus · June 21, 2013, 03:50:09 PM

Check the belts first

chazwood · June 22, 2013, 02:38:05 PM

Started bus.
Opened back panel.
Tested post 49 .....24 volts.
Tested post 48....23.7 volts
Tested post 33.....04 volts.
I guess I have alternator problems

Does anyone have a lead on who rebuilds 50dn's in the southeast?

Lin · June 22, 2013, 03:34:11 PM

I believe that our local auto electric shop does, so I would hope that one there would also. Have you called any yet?

Lee Bradley · June 22, 2013, 03:43:41 PM

Bad diode? Might be able to fix that in place.

bevans6 · June 23, 2013, 02:52:55 PM

That pin 33 voltage makes me think it's a bad diode. If I have it right that voltage should be around 12 - 14.

That is the infamous R terminal...

Brian

chazwood · June 24, 2013, 09:24:12 AM

Quote from: Lin on June 22, 2013, 03:34:11 PM
I believe that our local auto electric shop does, so I would hope that one there would also. Have you called any yet?

Got a quote from a local who said $1200 I think he just assumes he will replace everything.

Quote from: Lee Bradley
link=topic=25880.msg284086#msg284086 date=1371941021
Quote from: Lee Bradley on June 22, 2013, 03:43:41 PM
Bad diode? Might be able to fix that in place.
Don't know about finding parts for this generator.
Quote from: bevans6 on June 23, 2013, 02:52:55 PM
That pin 33 voltage makes me think it's a bad diode. If I have it right that voltage should be around 12 - 14.
Yes, it should be around 12-14
Where can I get diodes for this thing?

That is the infamous R terminal...

Brian

chazwood · June 24, 2013, 09:25:37 AM

Wow don't let me anywhere near the quote button. Hope you can make sense of my answers to those posts

chazwood · June 24, 2013, 09:45:21 AM

Bottom line is...where do you get parts for these things?

bevans6 · June 24, 2013, 10:37:24 AM

I have dealt with these guys in the past. http://www.elreg.com/Delco-Remy-50DN.html

There is a pretty complete diagnostic and repair section on the 50DN in the MCI manual here: http://www.buses101.com/PDF_Files/MCI%209%20Maint%20Manual%20in%20PDF%20format/MC-9%20-%20Maint%20Manual%20Section%207.pdf

Brian

luvrbus · June 24, 2013, 10:46:29 AM

Check the diodes you need a 300ohms meter reverse the leads if below 300ohms they are bad