# DeWalt DW621 problem - motor pulsing



## blinkh2 (Dec 19, 2011)

I have a dewalt dw 621 type 1 and the motor is pulsing when I turn it on. Adjusting the speed control still increases or decreases the speed but does not stop the pulsing effect. It will periodically run at full speed but not for more than 20 secs and then the motor speed will slow and speed up and slow again. Any ideas?[/I]


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## blinkh2 (Dec 19, 2011)

sorry, I meant to post this in another thread


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## bobj3 (Jan 17, 2006)

HI Tim

It sounds like the variable speed device is going south, time to replace it ..you can by pass it to make sure the motor is ok b/4 you do..if you are not comfortable doing the job take to a service center and let them CHECK it out for you..most big towns have one.(DeWalt repair service center)



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blinkh2 said:


> I have a dewalt dw 621 type 1 and the motor is pulsing when I turn it on. Adjusting the speed control still increases or decreases the speed but does not stop the pulsing effect. It will periodically run at full speed but not for more than 20 secs and then the motor speed will slow and speed up and slow again. Any ideas?[/i]


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## blinkh2 (Dec 19, 2011)

I am comfortable attempting to see if the motor is bad. It looks like the speed control is about $65 and the dewalt guaranteed repair is $130 so if I can save some money and do it myself then great. Please let me know how to bypass the speed control.
Thanks


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## bobj3 (Jan 17, 2006)

Hi Tim

" Please let me know how to bypass the speed control. "

"This is how I prefer to do it" 

I don't have a blueprint on that router in front of me BUT most are made about the same..
This is what I would do, 1st.clamp the router down to the work bench, pull out a router control box or a power outlet let bar with a switch on it,, find a temp.power cord, find the wires going to to brushes cut the lines going to them so I could isolate the speed control on the router or to say take it out of line.

Once that's done hook up the temp. power cord lines to the wires going to the brushes with jumper wires, turn off the router speed control box or outlet bar then plug in the temp. power cord, making sure the wire are not touching anything then hit the power switch on the speed control box /power bar,if the motor is OK it should run at high speed or what every you have it set on the router speed control box..if it runs you found the error than buy the new part and replace it..if not replace the brushes and run the test one more time if it runs your got it, repair the wire you cut and button it up..

You may say why not replace the brushes right off the bat because it doesn't sound like brushes to me ,no need replace good parts with more new good parts..

Hope this helps

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blinkh2 said:


> I am comfortable attempting to see if the motor is bad. It looks like the speed control is about $65 and the dewalt guaranteed repair is $130 so if I can save some money and do it myself then great. Please let me know how to bypass the speed control.
> Thanks


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## Dmeadows (Jun 28, 2011)

bobj3 said:


> Hi Tim
> 
> " Please let me know how to bypass the speed control. "
> 
> ...


DO NOT DO THIS!! Guaranteed to burn up something! The field and armature are in series normally. Powering just the armature will probably fry it!!!!


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## bobj3 (Jan 17, 2006)

Hi

I had the same error on the router below and it worked just fine, you will also see the router speed control box I now use on that router ...(PC 3 1/4hp )

I should say I took one of the hot lines coming (black one) into the router and just when around the speed device and just isolate the device box and taking it out of the path..the device will pull power from the white line but it's just floating without the black line going to it,so to say no need to play with it..or to remove it..

But you are right if your not sure take it to a repair shop and let them do it for you.. 

http://www.routerforums.com/woodworking-classifieds/26420-porter-cable-speedmatic-type-1-plunge.html
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Dmeadows said:


> DO NOT DO THIS!! Guaranteed to burn up something! The field and armature are in series normally. Powering just the armature will probably fry it!!!!


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## Dmeadows (Jun 28, 2011)

Bob, I agree that bypassing the routers speed control module is a good test procedure. However cutting both brush leads and connecting a power cord directly to both brushes also bypasses the field winding. Neither the armature or the outboard speed control are likely to survive unless the circuit breaker pops VERY quickly!

Solid state devices as in the speed control fail much quicker than fuses, let alone circuit breakers.

I hope I have misread your directions, but having reread them several times, I still come to the same conclusion. As a repair tech for 35 years, I hesitate to post a correct procedure, for liability reasons and for the possibility of being misread.

A local repair facility may indeed be the best option!


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## bobj3 (Jan 17, 2006)

Hi

" As a repair tech for 35 years " give it a shot he just wants to know how to do it right..

" what one man can do a norther can do also "
http://www.youtube.com/watch?v=9ALOI63X_CE

It can be hard to do sometimes but most will get the job done
http://www.youtube.com/watch?v=_2MhQGFWdYU&feature=related

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Dmeadows said:


> Bob, I agree that bypassing the routers speed control module is a good test procedure. However cutting both brush leads and connecting a power cord directly to both brushes also bypasses the field winding. Neither the armature or the outboard speed control are likely to survive unless the circuit breaker pops VERY quickly!
> 
> Solid state devices as in the speed control fail much quicker than fuses, let alone circuit breakers.
> 
> ...


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