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What am I doing wrong now

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Andy C29/07/2017 16:03:45
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478 forum posts
120 photos

hi everyone

I have recently bought a new little brushed motor and a set of suppressors. Easy I thought, even read the instructions that came with them and did a search here for any other useful information. Found an interesting discussion started a long time ago about whether they are needed or not. Not opening that can of worms again. Just going to fit them.

Armed with some sandpaper to roughen the surface, some solder and my trusty iron, off I went on a journey to not working and back again.

So, not to be deterred I grabbed a great big rasp from the tool box and roughened it a bit more. Hotel not working for an overnight stay. After a big breakfast of "I am not going to give up" I grabbed some different solder, fired up the gas torch and tried again. This trip is seriously bugging my melon man.

So what the heck is going wrong? Wrong solder, still not rough enough or something else entirely?

To save on trips to "this is still not working" I submit myself to your thoughts.

Cheers

Andy

Paul T29/07/2017 16:25:45
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7340 forum posts
1229 photos
2 articles

Hi Andy

Sounds like the can isn't getting hot enough for the solder to stick or the metal isn't clean enough for the solder to stick.

I use the tip of the iron to pre heat the area before trying to solder and I use plumbers flux to keep the metal from oxidising when soldering a tag onto a can.

Paul

Dodgy Geezer29/07/2017 16:53:30
818 forum posts
59 photos

I swear by plumber's 'Active' flux, which is an acidic compound. With it, you don't even have to clean most copper surfaces, and it seems to make solder stick to most metals...

Andy C29/07/2017 17:10:13
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478 forum posts
120 photos

Cheers. I will look that up and try again

Andy

Colin Bishop29/07/2017 17:37:16
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Moderator
5192 forum posts
6120 photos
421 articles

Paul is probably right, the can isn't getting hot enough but if you do manage to apply enough heat you might damage the motor, especially if the end plates are nylon or have nylon bearings.

Do the suppressors need to attach directly to the can? Usually it is sufficient to simply bridge the supply terminals. If you must attach to the can then many motors will have mounting screw holes on the front face and you can simply make a tag mechanical connection to one of those using a small (and short!) screw.

Colin

Malcolm Frary29/07/2017 20:46:05
1043 forum posts

a) there is a thin chance that the metal won't solder.

b) I have yet to need anything other than a single capacitor across the terminals. On small motors with tags with holes in, I poke the capacitor legs through and solder them, then use the excess wire as a more useful tag.

Apart from using the right flux and tinning, the trick is a big enough hot enough iron to get the metal hot enough quickly enough that the heat doesn't have time to travel to areas where damage will occur. My basic reason for not doing it.

As an aside, if one of the "side" capacitors goes disconnected there is a strong-ish theory that any interference, rather than cancelling, will enhance due to the imbalance created.

Andy C29/07/2017 21:01:09
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478 forum posts
120 photos

Okay, I have soldered the on across the terminals. I will try again and if no success I will leave it at the one. It was just that the instructions said to install the three. I will also investigate if I can add tags to the can with screws too.

Thanks for the help.

While I have you though, could I ask one more.

I am putting a car windscreen pump in one of Ashley's LCMs. The set up is an action speed controller, main board and switch. I have a great diagram from Mr Milbourn and it all works great by using a spare channel to operate the pump. However I have a twin outlet pump, thinking it would squirt water through both outlets at the same time. Ha ha, no only one side squirts. So he other side must be switched differently in a car. Can it be set up to do this in the boat. I.e. Left stick left fires one outlet, left stick right fires the other. Works okay with one and a splitter, but two independent would be awesome.

Cheers

Andy

Banjoman29/07/2017 21:24:30
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1146 forum posts
2423 photos

Andy,

I have had similar problems with unseuccesful soldering direct to the motor can, but happened to read somewhere or other that if such were the case, a work-around would be to take a strip of thin copper sheet, wrap that around the can, simply put the capacitor legs under the strip and secure the whole thing with a small screw-and-nut through the ends of the strip.

As the below photo shows, I then also used the strip to earth the can to the propeller shaft ...

hlbygg43.jpg

Mattias

Edited By Banjoman on 29/07/2017 21:24:49

ashley needham30/07/2017 08:47:03
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7637 forum posts
159 photos

Like Malcolm, the motors with just one capacitor across the terminals have given no problems. I have in the past struggled and soldered capacitors to the can but don't bother any more.

I would try just one capacitor and in the unlikely event you get interference, do as Colin suggests. The propshaft tag is also a good and easy idea. In the case of the above, a wire around one of the mounting screws would do

​OR use a brushless motor....job done.

​Ashley

Malcolm Frary30/07/2017 09:25:56
1043 forum posts

I am putting a car windscreen pump in one of Ashley's LCMs. The set up is an action speed controller, main board and switch. I have a great diagram from Mr Milbourn and it all works great by using a spare channel to operate the pump. However I have a twin outlet pump, thinking it would squirt water through both outlets at the same time. Ha ha, no only one side squirts. So he other side must be switched differently in a car. Can it be set up to do this in the boat. I.e. Left stick left fires one outlet, left stick right fires the other. Works okay with one and a splitter, but two independent would be awesome.

That depends on the particular details of the pump and the wiring of the car it was intended for. I can imagine lots of ways of doing it, but probably all wrong, depending on the pump. Most screen pumps are a centrifugal impeller in a chamber, whichever way they turn water in the middle is thrown outwards, its only escape is through a hole in the side, and off up the pipe.

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