Has anyone had any problems with the electronic speed control on their
Hitachi M12V? In the middle of a large job, it's starting to act up, reving
up then slowing down, whether I'm in a cut or not. Pulled the brushes, lots
left there, although some minor chips out of a couple of corners. cleaned
out the brush housings (just vac'd it) and put it all back together. Runs
fine for one cut, then starts acting up again.
The cut I'm making is with a 1 1/8" pattern cutting bit (bearing on the
shaft and unused for this cut) removing about a 1/4" depth, by a 1/2" width
I have the same router and never had a problem with it. Speed was constant.
My only guess is could be the chipped brushes???
Does the motor spin freely by hand (being unplugged of course), no type of
binding in the rotation?
Somewhere I read about another brand doing the same thing. Seems they used
and LED or something as a timing light thingy to control the speed. Dust
had gotten up around the light somewhere or how and was affecting the
control of the speed. They blew out the dust and that did it. Yeah, guess
who found it, blew out the dust and presented the bill.
Don't know whether Hitachi does it the same way or not....
I use DeWalt 621s and had one just stop starting. Took it to repair place
and they blew out around somewhere on the inside that fixed that too.
Now blow mine out regularly so this must have been deep inside..
I think that you may have overlooked the obvious. Take a look at the speed
control. Try moving it back and forth between maximum and minimum speed
settings a few times to see if that helps.
From the parts drawing, it appears that it may be a sealed unit. I haven't
had to open mine up so I can't be certain. For reference, the part number is
301-819 and is described as Controller Circuit 100V - 127V.
Hope this helps. Let us know how you make out.
Although I've never had to open mine up, it should be similar to
Thanks for your reply. After blowing out the unit while closed, I opened up
the top cap. The speed control unit is sealed, as you said and sits on top
of the shaft. This makes me think that it is some sort of optical control
(LED controlled) as suggested by another poster. There didn't appear to be
any breaks in the seal, but iI blew it out where the shaft to the speed
control dial enters the unit. Was also able to blow out considerably more
dust with the top cap off than without (of course). All this and it still
jumps speeds. I have noticed that it only jumps to higher speeds though, it
doesn't get bogged down.
The mystery continues.
snip of an annoying problem.
Yep. Had an intermitent unit. Router would run or not. If I pressed
down on the top of the speed control module it would run for a while.
I had a hole drilled in the top cover of the rounter to get a screw
driver in to press if needed. Finally got tired of dicking around
with it and just took it out. Only runs at high speed now but I have
never needed to slow it down anyway. Undo a couple of wires and remake
the connections on the input to the motor was all it took. It's kind
of a pricey part, around 80 bucks as I recall and it is a sealed unit
BTW and not repairable.
Yeah, I got that one. All they do is direct you to the nearest repair
center, which wants $45 to direct an airhose on it, which I've already done.
Besides, they're 3 weeks behind on airhose directing, and I'm just
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