Update to Bow Thruster will not go down


Stephen Davis
 

I’ve managed to remove the defective circuit board from the bow thruster control box, and am attaching a couple more picture which will allow you to see the damaged resistor. 


Steve
Aloha SM #72


Stefan Jeukendrup
 

Hi Steve,

Well done.

Does not look like a plain resistor to me, could be a varistor, NTC or PTC. But also could be a diode, is there a stripe on one side?

Its clearly a pair and only one of them got hot. You can replace it but you must also find the reason why this component failed.

Send me a private message on eeg@... and I will try to help you.


Stefan Jeukendrup

sv Malaka Queen

SM2k #348 @ Northern Ireland



Op 24-09-2021 om 17:24 schreef Stephen Davis:

I’ve managed to remove the defective circuit board from the bow thruster control box, and am attaching a couple more picture which will allow you to see the damaged resistor. 


Steve
Aloha SM #72


Mark McGovern
 

Steve,

That looks like a diode that failed, not a resistor.  If the tracks on the PCB are intact, you should be able to replace the diode.  If the PCB track has also failed you can use a short piece of wire to bypass the track.  As Stefan noted, if there is some underlying problem, it might fail again.  The diode should have a part number printed on it.  Google the part number and you will likely be able to find a replacement at a place like Mouser or Digikey.  Note that diodes are like electronic check valves that allow current to flow one way but not the other.  Therefore, they are "directional" in their installation.  Take lots of pics and note how the failed diode was installed so that you install the replacement diode in the same orientation.

--
Mark McGovern
SM #440 Cara
Belfast, ME USA


Stephen Davis
 

Hi Mark,

Thanks for the help. Obviously, I’m a bit out of my element if I thought the failed component was a resistor when it is actually a diode. I just emailed the pictures of the board to a company that repairs them, and they said the trace was too damaged to repair the board. The only labeling on the diode I can make out are T47-87, and I did not get any hits on that. Whether or not I have an underlying problem is an excellent question. I had the thruster up and down twice in the hour before it failed, and it was working fine. Considering the boat is 29 years old, I guess it is jus possible it was time to go. 


steve
Aloha SM #72


Mark McGovern
 

Steve,

No problem.  I am by no means an expert but it sounds like Stefan might be able to assist you in identifying the component and possibly sourcing a similar one to replace it.  Here is a link to a diode that is similar to the one that was used in the Bowthruster PCBs found in later model SMs like mine:  https://www.newark.com/vishay/gi754-e3-73/rectifier-diode-single-400-v-6/dp/97K0535?CMP=AFC-SF-T11-US

And if the trace is indeed damaged beyond repair, you can solder a small piece of wire in it's place to complete the circuit between the two through-holes that the trace previously connected.

--
Mark McGovern
SM #440 Cara
Block Island, RI USA