minnkota 765mx powerdrive

[tmorriss]

Hello. I have this bow mount trolling motor. It had worked fine. It is older I believe and it came with this used boat I purchased about 9 years ago.
The ser # is MK01469380 . I can't match up the number with anything Minnkota documents, but I suspect it's an 01'. regardless, it's older
Anyway, I just stopped turning with the footpedal. The motor runs.It runs in both MOM and CON. The foot pedal will make it run in MOM, however, it will not turn.

I'm not sure how to diagnose what is wrong here. I think the foot pedal is ok though because using the foot pedal and a multi-meter, I can see continuity across the pins on the plug when I step on the pedal, both right and left. (maybe I'm wrong on this part though).

Any tips on what I might be able to check would be appreciated.
thx

 

[tmorriss]

I've taken this apart to do some checking with my meter.
The yellow and green wires from the power cable where it enters the control box go right to the motor drive unit. THey don't go to the control board. I assume these are what makes this turn?
When I do measurements here across these two, while pushing on the pedal to turn I get some strange measurements. I get about 10.4V turning L and 8.5 turning R. This seems to be the case whether I'm in CON or MOM.
What is also odd, or at least I never noticed it, is that even though the speed control is on zero, when I touch the pedal in either CON or MOM, the prop turns slowly?
Why should the prop be turning when I'm in CON and I'm just pushing the pedal to turn the motor?

Does anyone know if I should be getting a full 12V here?
If so, does that take the control board out of the picture and point to the foot pedal?

Is there a way to check any of this?

Thx in advance

 

[tmorriss]

Ok... I just did more measurements on this. After pressing the foot pedal about 20 times, now it doesn't make the prop spin when speed is on zero. Go figure.

measuring the green and yellow wires, using foot pedal in L then R I get the following where these two wires connect with the M/F spade terminals.

Using my meter, with one probe on green and one to ground
Foot pedal L turn 0.6V R turn 11.6V

With one probe on yellow and one to ground
Foot Pedal L turn 11.6V R turn 0.6V

Then measuring across the yellow and green, one probe on each

L turn about 10.9 R turn 10

Appreciate any help,advice,suggestions. Thx

 

[jhande]

How about using the OHM function and test the foot pedal disconnected from the motor.
See if you are getting a reading between green and yellow.
That would isolate the pedal.

I'm not sure how the switches/foot pedal operates. It might send full juice through one circuit or possibly reverse the polarity.

Hopefully an experienced person chimes in.

 

[sam am I]

My understanding of the steering control is as jhandle mentioned.............The two wires just get their polarity reversed BUT at what voltage?

Not sure but if by design when the steering motors turns and it isn't a variable speed type then most likey, as jhandle mentioned, it just is 12V (and -12V) most likely that runs the steering motor.

You then can simulate the pedal by just hooking up 12V and gnd to the two wires that drive the steering motor...........then reverse the two wires to get it to turn the other way.

 

[tmorriss]

Thx folks. Well as it turns out, I was convinced it was something in the motor drive. Based on what I had stated above, I then tore the whole darn thing apart and took all the insides out of the motor drive. Made sure the moto spun by hand(it did). So then I checked that all the gears were properly positioned and turned (they did separately, but turn hard when the motor is in there, which I think is normal.
Then I got the bright idea to just hook the battery directly to the motor leads and see if it ran (it did, much to my surprise).
So I put it all back together and then hooked the battery up directly to the two power (red,black) and put the pedal down and viola... now it works.
I don't know if the gears were bound up? Or, if I had a bad connection and unplugged everything and then reconnecting fix that, or what.
You are correct , the polarity changes, which is what makes it turn R and L as I confirmed this also with the battery directly hooked up, by just swapping + and -. So, after days of messing with this and actually weeks of thinking about messing with it, it seems to work fine now. Thx for the info. I learned more about this thing that I really wanted to know Thank you all

 

[jhande]

Glad you got it working again.

 

[tmorriss]

As a final piece of info, I had also asked minnkota support about this, and provided them the same information . I did get a response from them today as follows:
"It appears the foot pedal is sending the appropriate voltages to the servo motor inside the steering housing but that servo motor is not responding. That tells me your servo motor is burned out or seized due to corrosion over time. You can try searching for a steering housing on ebay if someone is parting one out. Or, you can sell your motor for parts online and replace it with a new motor. "

So I take this to mean that they confirmed my readings were correct and ruled out anything with control board or foot pedal(which was my assumption as well, based on my limited knowledge of how this was suppose to work, and the lack of any real wiring diagram).
So if anyone has a similar issue in the future, I hope this may help them.

Me.... I'm going fishing!