Motorguide 45lb thrust foot controlled

[troy306]

The trolling motor will not work on 24 volt, and has lost power on 12 volt, could the motor have burned up, or is it an electrical problem? If its the motor where can I obtain a replacement motor? Thanks

 

[Silvertip]

Re: Motorguide 45lb thrust foot controlled

Armed with that little bit of information we can't begin to tell you what's wong? What have you done to troubleshoot the problem? 1) have you had both batteries load tested? 2) Are both batteries fully charged. 3) Have you disconnected and cleaned (shiny clean) every connection (not just looked at them) and are all connections tight? Is this a new to you boat? Did it ever work on 24V. Is there a 12/24 selector switch on the foot pedal? Is there a Charge/Run switch on the panel where the trolling motor receptable is located? How many wires are there running from the batteries to the receptacle. How many pins in the receptacle. See what we need here. Tell me what you have and I can probably provide a schematic. Just remember, we can't see your boat.

 

[motech]

Re: Motorguide 45lb thrust foot controlled

Hello,

I too have an issue with a Motorguide model 765, 45lb thrust motor. I'm an electronics tech and was asked to fix the variable speed control of the motor. I have downloaded the parts list and wiring diagram but the MOSFETs are all blown and the gate resistor on the PWM control board is smoked, I can't tell the value I need to replace it with.

It's not a very complex circuit and I've reverse-engineered much of the circuitry. It would be great to have an actual factory schematic if possible.

I don't believe the factory design is all that good in terms of the MOSFET driver. They use 4 BUZ71A MOSFETs all in parallel to handle the current draw of the motor. The issue with those devices is their "on" resistance is rather high, and there are many other devices with better specs at similar cost.

Anyway, if you could help me out with a schematic I'd appreciate it. I'll post my replacement choice here after testing it out. It will probably provide much better long term reliability.

 

[motech]

Re: Motorguide 45lb thrust foot controlled

I couldn't find a schematic on the 465 PWM, and the wiring diagram I found with parts list wasn't accurate to the unit I have.

So I decided to just figure it out, best I can. Find attached a complete schematic and wiring diagram for the MotorGuide model 765. I ordered the repair parts from Digikey, but until I get them and put them to the test I can't be confident in the repair.

Plus, I need to determine the value of the gate drive resistor. It's value is probably not critical, but we'll see.

Also, I could not determine the value of the small capacitors on the PWM board, but I seriously doubt they're bad.

Enjoy!