Hitachi M12V question

[Joe]

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 per pass.

Thanks,

Joe

[noreaster]

Snip

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?

[Joe]

That's my only guess as well. The motor does spin freely. With the brushes out, it spins *very* freely (of course).

Joe

[George H Hughes]

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..

[Peter Bogiatzidis]

Joe,

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.

Peter.

[Joe]

Peter,

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.

Joe

snip of an annoying problem.

[Mike in Arkansas]

[Will]

Why don't you call Hitachi, they have a 800 number??

[Joe]

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 impatient.

Joe