Katsu trimmer router will not start until I give it a spin

[Mel769]

Good evening hope someone can help; I bought a Katsu trimmer router back in April, so almost 6 months ago. Ive put it to good use in that time but yesterday it just stopped half way through a piece. Ive checked the brushes and there's plenty left on both & they dont look damaged atall. Ive stripped it down and checked for any obstructions ect and all looks good. With the power off it spins freely and is not impeded. With the power on I checked the voltage with a volt stick (in the body with the top off) and theres constant power there while wiggling the lead, so this rules out a dodgy lead.

Anyhow what ive discovered tonight after another look is that if I switch the power on and give it a slight spin manually (with the bit removed obviously) then that will get it going and all okay. However I do notice if i look through the vents that there's now quite (how can I put it) fierce sparking going on; more sparking than there was new when it was new im sure !

Would anyone have any ideas what could be wrong with it ? Im thinking it could be a dodgy speed control switch ?

 

[southendwoodworker]

I'd say is a warranty issue.

My limited electrical knowledge is that some motors need a capacitor to give it a kick like you've described to start it rotating. The starter capacitor could have blown. I don't know much about this though.

 

[Mel769]

I'd say is a warranty issue.

My limited electrical knowledge is that some motors need a capacitor to give it a kick like you've described to start it rotating. The starter capacitor could have blown. I don't know much about this though.

Okay thanks I will look into that, I cannot see a capacitor (or any electronics for that matter) other than the speed controller. The warranty is expired after 6 months I expect. I would like to repair it anyway !!

 

[Droogs]

Try giving @Myfordman a DM, he's the most knowledgeable bloke I know about twirly electrickery engines

 

[Essex Barn Workshop]

Good news is I can do a guaranteed fix for under £30!

https://www.aimtools.co.uk/collections/routers/products/11-86

 

[Mel769]

Yes I could maybe just get a replacement.

 

[D_W]

Those are right on the bubble of "deal" compared to makita in the US. The makita trimmers show up new for about 60 pounds equivalent from time to time, but they do actually have the power they say they do (about 800 watts -even though it's not that easy to use all of it in a trim router).

I'd buy another one and use the time spent to make things instead of sorting out tools that may or may not be worth the time.

 

[Mel769]

Thanks for the response its interesting. Thing is I would like to give it a shot at repairing it tbh before buying a replacement. The rotor does turn as I said; it just needs a tap to get it going; with that in mind I'm trying to reduce what's wrong with it ! Do these little trimmers even have capacitors? I will clean the commutator with cleaner, a toothbrush, and 400 grit w&d and see if that makes any difference. If not then try and get hold of a new speed controller and refit that. See I'm interested in what's wrong with it and trying to fix it before chucking in da bin. Thanks anyhow !!

 

[MARK.B.]

6 months old, should still be in warranty, give the people you bought it from a call or email , worth a shot and you have nothing to lose.

 

[Chrispy]

I'm sure you will find that one of the rotor windings has burnt out, if you have a meter you can check readings across the armature contacts. But they are not easy to dismantle.
BTW one of mine does the same.

 

[Mel769]

I'm sure you will find that one of the rotor windings has burnt out, if you have a meter you can check readings across the armature contacts. But they are not easy to dismantle.
BTW one of mine does the same.

Thanks for the info, I will buy another.

 

[XTiffy]

I did my apprenticeship in the RN as a Radio Electrical Artificer in the 60s. In those far off days we repaired to "component level" we also used to do coil winding (tranformers etc.). As you are keen to have a fiddle with the router, have a look on the internet for "Small ac electric motor faults and repairs", quite sure you will learn a lot.

 

[XTiffy]

I should have delved deeper! That router is probably a cheap copy from China of a "proper" trim router. I would say chalk it down to experience but I would not buy another, once bitten etc.! I did buy a similar trim router from Lidl or Aldi which has been quite good and they seem to stand by their warranty.
I wanted a router I could use one handed for light trimming, I have several other bigger routers that are awkward for very light trimming

 

[Spectric]

Cheaper to just buy a decent tool first time than put up with cheap copies that so often fail to deliver, quality always comes at a price. My Bosch 600 has done some hard work and apart from needing a new collet has worked great.

 

[okeydokey]

Are the brushes seated correctly on the armature it's unlikely but possible they have worn and are seated sideways or whatever so there is insufficient contact for enough current to pass and start the motor without giving it a nudge.
Give it a look if its not that issue (and you can't reseat them) and is you know where it came from send it back for another

 

[Spectric]

Are the brushes seated correctly on the armature it's unlikely but possible they have worn

It has probably just worn out and is now beyond economical repair, you may even have an open circuit segment so it cannot start in this position.

 

[clogs]

I have a desk top fan thats the same.....we used it mainly to cool the computor with a little to the operator.....
Progressively over time it got harder to start/spin up......
took it to bits and found the bearing bushes were a bit dry but everything else looked OK...
no burning etc.....
rebuild it and still the same.....just cut the lead off and in the recycle bin it went.........

 

[John Brown]

Far from being Chinese junk, I seem to remember the Katsu routers getting favourable reviews.
I can't speak from personal experience, though.

 

[dizjasta]

A possible solution?

 

[ChaiLatte]

Do these little trimmers even have capacitors?

As they are copies of the Makita RT 0700, maybe the exploded parts diagram for one of them might be helpful:

https://www.sparetoolparts.co.uk/makita-rt0700c-spare-parts-list.html