Fuse in a MK Troll motor? I may have toasted my Trolling Motor

[charly1954]

Not my day. Spent 2 days building a platform for my late model Minn Kota TM and may have ruined it. Hopeing there may be a reset or fuse but from memory I don't remember seeing a fuse when I took it apart. Long story short its a mid 1990's 812 auto pilot TM. Paid $25 years ago and never could get the prop to turn so last year I tore into it, first the electrical part then the motor. CLeaned the armature and brushes up and that was the problem.

After mounting it I thought the pedal plug pins looked very dirty so I took a small fine wire brush across the tips a few times and thought I seen some very minute arcs, that was stupid wasn't thinking I guess. After that I tested it and all that would work was the left/right turn, the prop would not turn.

So did I toast it, any ideas on what may have happened or if it can be fixing

Note: I was going to put a 50A inline fuse between the bat and TM but no place in town had one so I was going to order one online. I'm no electrician but I can't see a inline fuse stoping it cause it was caused from the pedal plug, I may be wrong,

 

[alldodge]

Don't know of a reset or fuse, but maybe just need to take it back apart and clean. Might just be more corrosion or bad connection since it sat for a while again

 

[charly1954]

While installing the platform and TM I had run it 4-5 times in the last 2 days and it worked everytime. Only time it didn't run was after I wire brushed the pins in the pedal plug. Read in another post last night to bypass the electronics and try to run the prop directly from battery, not sure how to do that but thinking maybe pop the cover off the top and use wires that run down shaft to prop.
I'm old enough to know better but wasn't thinking and in a hurry, makes me so ticked off at self.

 

[charly1954]

I hooked the prop pos/neg wire directly to my battery and the prop took off so no damage to the prop motor.
The left/right steering and auto pilot works so no damage there. So it looks like the problem is in the control board that turns the prop on.

 

[alldodge]

I hooked the prop pos/neg wire directly to my battery and the prop took off so no damage to the prop motor.
The left/right steering and auto pilot works so no damage there. So it looks like the problem is in the control board that turns the prop on.

The part that's usually hard to get or costly, bummer
I

 

[sam am I]

So you say you had it apart? Can you open it again and take several decent pictures of the control board/s?...Several each of the front and back, different angles would be most helpful.....


Clear'ish picture like my B-fast pic.........I call it a "Wuhan Special " BTW



Toasted Sour Dough English Muffin, Buttered (both halves). On the left half (only) Sliced Boiled Egg with TONS of Pepper. On the right half(only) Black Forest Ham, Topped w Sharp Cheddar Cheese. Nuke for 30 seconds, slap'um together!!!

 

[charly1954]

As S.Mariner said it is hard to get out, from memory he's right. I still have photos when I had it out before so I would have a picture on what wire go where before I pulled them off. But you wanting to see after the damage photos right?

 

[sam am I]

Yes and is there actual physical damage? Where is this damage? A printed circuit board? Sure, let me see both before and after if you got um....Give me everything you got and/or can get that is either obvious damage or not so obvious(e.g., the main controller printed circuit board)....

 

[charly1954]

Took it apart tonight it was dirty so I lightly brush/cleaned it, was easier than the first time. Except for power wires(1 set to motor 1 set coming from batteries) and 2 wires come from the gear box to turn left/right and go into a black oblong hard rubber piece. The rest of the wires go into a molded board that is not transparent. I don't see anything melted or burn, doesn't have a burnt electrical odor either. Maybe something in the board that's molded over toasted.

There's 1 red wire that goes to nothing, I has shrink tube on the end to cover wires end and its bend over to close the end. Nothing is melted on it and I would say it may have been for a accessary that's not included in this model.

I keep getting unknown error on pics upload. So I uploaded them to picturetrail.com, I've used this picture host site since 2002.
http://www.picturetrail.com/sfx/album/view/24857808

 

[gm280]

Do you own a multi-meter? If so, first thing to check is if there is voltage getting to the head unit. You have to start with the common basics. Verify you actually have power to the places you labeled pos, neg, on the picture to the power relay area. You can also remove either the black or red wire going to the motor and wire direct fro the pos neg wires to see if the motor works. Once you verify both those conditions, the rest is in the molded over section. So that means you isolated the problem area.

After that, it all depends on your electronics abilities. If you want to push further and know what you are doing, have at it... If not, get some local help... JMHO!

 

[sam am I]

Ok, so you did have the prop motor working before the sparks?

Hmmmm, bummer they didn't limit the current on the foot pedal plug feeds........Well engineered products usually do.....Like in the event the plug floods, get mashed or even has a guy with a metallic brush etc, those (any) I/O connections should limit current/fold back so the main board stays safe, well at any rate.....

From a tad bit of previous knowledge of a assumingly similar MK control board, with proper power hooked up etc, that white relay on the control board should "click" (turn on) when you hit the throttle (foot pedal). If not, the motor isn't getting it's high side voltage (static switched 12/24 volts), most likely the control board isn't working properly, see ref link here.

If the relay is clicking but, still no prop joy, the low side (dynamically switched ground) PWM circuit isn't working..........Again, the board isn't working (PWM IC and/or associated components, see same ref link here) but, I know ppl that can fix it....BUT, is it worth it? Potting has to be removed etc....It can be done and I'm cheap enough to stick it to the man but....

Nice pic's BTW, ty

 

[charly1954]

tks for the input GM and Sam its appreciated, trying to answer both your questions in one post.

Yes it was all working before I lightly brushed the pedal plug pins, and if it hadn't been nighttime I probably would not have seen the tiny sparks. These where tiny arcs not sparks flying.

As I said earlier the prop wired directly to the battery, the prop runs. The left/right steering and auto pilot work so they are getting juice but the prop is not. So there is voltage getting to the head unit for the auto pilot gyro board but not the prop.

On the pedal wire diagram a white wire comes off both pedal prop switches. That white wire goes into the control board and possible runs to the white box that turns on a switch and lets juice go to the prop.

Using a multimeter there's 12.68 volts on the wires going into the control board from the battery. So from that point to the wires coming out of the board going to the prop is where the problem is, inside the board or the white box that sam said should click is where the damage has to be. I am very hard hearing and when I do this test I probably wouldn't be able to hear if it clicks so I'll have the wife listen.

I'm mechanical and logical when trying to figure things out but I'm no electronic expert so I'm very limited on trying to test wires going into the molded board using a wiring system schematics. So wire diagrams I am useless at reading them.

 

[charly1954]

Video I found on how to bypass the control board to get the prop to run, 3:45 minute video. This would be a last resort for me, he splices the Neg wire going to the head to the battery Neg that's pluged into the control box. Wondering if this is safe?.

The TM in the video has a empty head to install a speed controler. so I wouldn't be able to add a speed control inside the head like this video shows cause mine has the gyro and a board, without one it would be full power or nothing. I would have to find another place to add a speed controller.

 

[charly1954]

I just listen for the click. On both prop pedals it clicked when pressed or turned on and clicked again when released or turned off. I may have to go with the video but really didn't want to, guess I do a little searching for a board. With it being a 20+ yr old model finding one will not be easy and probably costly, just like parts for my 1968 20hp Mercury outboard which was made to last.

 

[sam am I]

Yeah so those since the relay clicked (turned on), you should then be getting the 12/24V solid voltage reading on that red wire that leads off the board to the motor......Check that first, the relay's contacts might be pitted and happen stance only intermittently supplying the necessary high side 12/24V.

If the motor's red wire is in fact reading the 12/24V when the relay clicks (turns on), then the low side PWM isn't working and the board (component/s on) appears to have failed..

 

[charly1954]

I think I already tested the 12v Pos/Neg wires going to the motor head and when I pushed on either prop pedal it read nothing, no volt reading at all. Its easier to test the pos/neg wires coming into the head than tearing of the control board cover and trying to touch the wires on the inside. Its tight in there and I don't want to mistouch the wrong wire and mess something else up. Its 1am now so I'll retest that tomorrow to make sure. They way it looks its broke and unrepairable or to costly to get it repaired and there's no new part to be found.

I spent almost an hour tonight looking for a board and found nothing.
This site has no minn kota parts, found this site.https://www.fish307.com/content/schematics/minnkota/1994/865812824.pdf and I used the part number from the diagram from this site and nothing out there for sale online

What do you think of the video bypass, do you think it would work or be safe. .

 

[sam am I]

I think I already tested the 12v Pos/Neg wires going to the motor head and when I pushed on either prop pedal it read nothing, no volt reading at all.

Hold up.......

Either way, once that relay clicks (throttle on either pedal), that red wire, wherever you check it, HAS to read/feed 12/24V to the motor.

Think of it this way.........You have a DC motor and you want to turn it off and on using a toggle switch BUT, you want to turn it off and on with the battery neg. wire, easy enough, right? .......... So you hook up the +12 directly (red wire) to the motor and you splice the toggle switch in on the neg (blk wire) batt feed, thus, you use the negative/ground feed/wire to stop and start the motor.

This is how the control circuit works cept it switches the toggle switch (transistors) for you only VERY fast. This fast switching of the ground feed is how the speed of the motor is controlled and if the +12V is missing, the motor ain't going to work eh?

 

[charly1954]

nothing when tested wires going to motor head when either pedal was pressed and relay clicked, tried 4-5 times still nothing. I lightly tape the relay in a few spots when pressing the pedal and still nothing. Thought maybe it might jiggle something to make some contact.

 

[sam am I]

Sooooo,

Back up!! Sounds like you'll have to chase that red wire back to the controller......

Does the red wire voltage at the controller board read 12/24V when the relay clicks?

If so, somewhere's between the controller and the motor the 12/24V is getting lost(open).

If not, the relay(or its feed trace) is shot.

 

[charly1954]

Checked it few times already and right where the wires come out of the control board going to the motor have no juice. Battery wire going into the board has 12.68v. As I said before somewhere after the battery wires go into the board and before they come out to the head is the problem. 12v going it and noting coming out so probably 9999% sure the white box(relay) is bad.

No way to replace it so looks like I will be trying the video suggestions to get the prop to run. Splice the Neg wire going to the head to the Neg wire from battery which is pluged into the board. THen add a speed control to adjust the prop speed and maybe a toggle switch to shut off power. Here's is what the guy used. I read thru it and it says its industrial grade quality. Finding a place to put it is the only problem. THe guy in video put it inside the head but mine has the compus/gyro system so it won't fit in there.

Tks so much for all your input and help. Hopeing to have it going in a week or so with the bypass