Northern Lights Genset Brushes

Post here if you want to discuss a topic specific to the MV/32, MV/34, and MV/41.
Post Reply
Pisgah
deckhand
deckhand
Posts: 8
Joined: Thu Jan 14, 2021 11:25 am

Northern Lights Genset Brushes

Post by Pisgah »

I stopped getting voltage to my panel from my NL generator the other day. The service dept at NL was very helpful with diagnostic steps. The first was a resistance check on the brushes. Instead of perfection which would be a little over 16 ohms, I got 127. I’m trying to figure out how to access the brushes to examine them. Can anyone help?
Randy Catlin
Nighthawk
PDQ34

deising
admiral
admiral
Posts: 315
Joined: Mon Sep 15, 2014 3:48 pm
Location: Punta Gorda, FL
Contact:

Re: Northern Lights Genset Brushes

Post by deising »

When you say you stopped getting voltage, that implies zero output. I had that happen once and found a fuse in the control box was blown. Replacing that restored operation and it has worked fine for several years.

Are you sure the brushes are your problem?
Duane Ising
m/v Diva Di
Punta Gorda, FL
2006 PDQ MV 34 - hull 91, 75HP, 3-blade

Pisgah
deckhand
deckhand
Posts: 8
Joined: Thu Jan 14, 2021 11:25 am

Re: Northern Lights Genset Brushes

Post by Pisgah »

The three relays seem to be fine. My AVR has a fuse holder on the board, but there is no fuse, there is a copper wire slug of the same diameter, which apparently was supplied by NL. The rest of the board has no obvious signs of failure.
I think I have to check the brushes. I wouldn’t think they’re worn down since the generator has less than 400 hours since 2006. If they are indeed the problem, I think it more likely that they just need to be cleaned.
It was suggested that I try to access the brushes by opening up the bulkhead at the back of the locker under the fridge. That area was covered with insulation by a prior owner. I hope to avoid surgery.
Thanks,
Nighthawk
PDQ 34

makala
1st mate
1st mate
Posts: 26
Joined: Tue Jan 17, 2017 11:18 am

Re: Northern Lights Genset Brushes

Post by makala »

I just played with my generator for a couple of days (see post about checking the NL generator 12V ground). If the engine runs it's not any of the four 12V relays (I studied the wiring diagram for days when troubleshooting my generator).

Obviously you probably checked the 120v circuit breakers on the side of the control box. You might want to try to check if you are getting 120 volts on both sides when it's running if possible.

If you unscrew the four brackets holding the generator base "tray" to the hull you can slide the generator forward several inches. After sliding forward you will see about 4-5" of clearance at the generator (aft) end, which looked like it would be enough to remove the cover and get to the brushes with a shorty screwdriver, perhaps using a mirror for help.

I wouldn't advise cutting from behind the refrigerator. The area is sealed for a reason (sound and CO emissions, likely). On ours (2006) there is a plenum to provide fresh air to the generator head that you would also have to cut into. Not worth it.

You could feasibly slide it more forward if you disconnected the four isolators the generator, but I don't think it's necessary...

Let us know how it goes... I am thinking about replacing ours as a matter of maintenance since we are creeping up on 2500 hours and brushes are cheap (in marine bucks anyways)!

Oops, almost forgot- One thing I read regarding 120 power output is that if you aren't getting it you could try to "flash the field", see here:

https://www.cruisersforum.com/forums/f1 ... 50885.html

Thanks,
Doug
B-Side MV 34 #102

Pisgah
deckhand
deckhand
Posts: 8
Joined: Thu Jan 14, 2021 11:25 am

Re: Northern Lights Genset Brushes

Post by Pisgah »

Thanks for the input!
When I did a follow up check of the brushes, they were fine. At the suggestion of NL and helpful fellow PDQ owners, I flashed the field, a very simple procedure.
Problem solved!

makala
1st mate
1st mate
Posts: 26
Joined: Tue Jan 17, 2017 11:18 am

Re: Northern Lights Genset Brushes

Post by makala »

Pisgah wrote:
Sat Sep 25, 2021 9:18 am
Thanks for the input!
When I did a follow up check of the brushes, they were fine. At the suggestion of NL and helpful fellow PDQ owners, I flashed the field, a very simple procedure.
Problem solved!
Hi Randy,

Can you post the procedure you followed to flash the field for our NL generators? It would be nice to have it documented in the forum for others with the same problem.

Thanks!
Doug

Post Reply