how to bypass dremel tool internal variable speed control?

Hi

Just take it apart, I'm pretty sure it's just a "potentiometer" (variable resistor) so it would only have 3 leads, one from the external wire to the pot., one from the pot to the motor, and one from the other external wire to the other lead of the motor.

Cut things off, plug the external leads directly to the motor.

You can make yourself something that would do the same with a variable light controller (those you have to control your house lights) Get one of these, one wall plug unit and one extension cord.

PWR IN (1) to VARIABLE (1) VARIABLE (2) to PWR OUT (1) PWR IN (2) to PWR OUT (2)

it would be an awesome idea to tape everything together to cover the connections once you're done so you don't get shocked everytime you want to slow it down or speed it up :)

Have fun

(PS I also have one of the new Dremel units and it smokes too ... Uh.)

I'm not positive, but I would think if you just soldered a wire around the speed control it would run at full speed, I could be wrong though.

-Landon

Unfortuantely it doesn't seem that simple. The speed control has what looks like a some kind of semiconductor/IC (3 leads), a diode, and maybe a fixed resistor in addition to the slide pot. I don't know if they're doing pulse width modulation or what.

If you cannot figure that out by looking, you probably should not be dicking around with it.

The last fried speed control in a chinese one I bought, took a buck's worth of a new triac to fix.

Cheers Trevor Jones

I doubt they have put a stepper motor in there, they wouldn't sell for

20$ each! -- You still should only have two leads coming out of the motor. Confirm?

Btw you said there was a IC ... how many pins does it has, can u give out the ID (in case it's a bridge or something so your motor would be DC (Uhm?!) and wouldnt be a great idea to plug it right into a wall outlet!

Of course it's not gonna be a pot, it would have to be far too big and burn up a lot of power. Instead they use what is essentially a light dimmer. The semiconductor you see is a triac, the diode is a diac to trigger it, if you just jumper together the right two pins on the triac, the motor will be forced on.

It sounds like you're describing a light dimmer circuit. See

for an example of a typical circuit. If your circuit is like that one, running a jumper wire across TR1 will get you going at full speed. I presume you can figure out which two of the three thyrister leads. And you do know your safety rules for working with mains powered equipment, right?

the speed control is a triac based phase control, the same as a light dimmer - typically it has two wires, just short the two wires together and the dremel will run full speed all the time.

--
Posted via a free Usenet account from http://www.teranews.com

Mine had a smd triac BT134W which was faulty.

I replaced it (easy!!) with a new one, and the dremel has worked years after that. The triac costs about 1 usd.. The parts are on a white ceramic circuitboard.

Kristian Ukkonen.

Don' it just hurt to the core, James ... ? !!! ;~)

Arfa

. . .

This is one of those cases where "If you don't know already, you probably shouldn't be doing the job".

The wiring should be simple enough to do it by inspection. If it isn't, you really need the schematic and the ability to understand it.

Unlike the other poster, I really doubt that the motor speed control is just a pot.

--
Bill Fuhrmann

Thanks, folks. This discussion is exactly the type of info I needed.

Every Dremel tool I've had apart used a universal motor, and the speed control was a simple dimmer circuit. This one might be PWM, and run the motor on DC.

--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

None of those I've seen used an IC in the speed control. Also, he didn't mention a filter capacitor, so id may be a simple dimmer circuit. It's hard to tell from such a vague description. Part numbers would have been a big help.

BTW, have you seen the small DC powered clone at Harbor Freight? It runs on 12 VDC, and comes with an AC adapter. I was thinking about using one (or more, with different sized drills) with a homebrew CNC machine to drill PC boards.

--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

I took a look at google images for his model and the dimmer really is just a dimmer ... providing they sell brushes kits (2) for his model, the principle was ok from the first post; plug it right to the input.

If the person who originally posted the question still follows the discussion; it is strongly suggested that you do NOT use the tool wired that way for too long as the motor will overheat and break (or some of its internals will melt down)... take it as a temporary fix only.

Or do like I did. I took a 600 watt dimmer and put it in a project box with a cord on one end, and a receptacle on the other. I use it to control the speed of dremel type tools (anything with universal motor under about 400 watts) and to regulate output of my soldering iron. Also comes in handy to dim the occaisional lamp.

As long as you don't run it wide open for long periods of time it will last as long as if you had the built-in speed control. My luck with Dremels has been terrible. The cheap chinese crap lasts just as long, for 1/4 the price. Much as I hate chinese crap.

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Posted via a free Usenet account from http://www.teranews.com

after you make your temporary repair, dremel sells all the parts you might need for a nominal cost if you call customer service.

I was like that once - long ago.

Then I got my first DIE GRINDER!

OOOOOoooohhhh Baby.

Atomic powered Dremel.

What a TOOL to have in hand. Oh, The POWER!

But warning - this dude ain't for balsa wood, kiddies.

And you probably outta practice on something else before trimming those gnarly toe nails...