Repairing a Dremel 4000

So someone at my workplace accidentally plugged my 110v rated Dremel 4000 to a 220v source. With the amount of smoke that came out, I was pretty sure it was a goner.

But I attempted a fix anyway and guess what, those Germans sure made one hell of a machine. Everything is modular and repairable, gotta love precision German Engineering :D

The Dremel 4000 is one of the most popular tools for makers and hobbyists out there. So there's plenty of resource online to fixing it. The best one to find out exactly what's wrong with your Dremel 4000 is eReplacement part's page on dremel parts. Just look replacement part by symptoms and you'll have a general idea on what might might have gone wrong.

iFixit's page on the Dremel 4000 is a great resource on how to take it apart. I did try asking on iFixit's forum on asking about my problem directly, but it went unanswered till this day.

After a moderate level of looking around, I was pretty sure it was my electrical assembly that died out. I would also need to check the coils if they burned out too by any chance.

So now to take it apart. iFixit has quite amazing documentation on how to take the dremel 4000 apart. Just follow through step 1 to 14 from here and you'll be done in no time.

It was pretty obvious from the looks of it what I was dealing with here. But just to make sure if it was just the electrical assembly, we need to check the coils.

After doing a continuity check on the Secondary coil and the armature, I was convinced they were fine. And it was just the electrical assembly that needed replacing.

I ordered the electrical assembly from amazon

1) Dremel Electrical Assembly
https://www.amazon.com/Dremel-Parts-2610004636-Ele...

So after waiting aroud 3 weeks for the Electrical Assembly to ship to my country, we're finally ready to bring this Dremel 4000 back to life

So there's not much information well documented on connecting the three electrical assembly wires. I had to do alot of digging around until i finally found a video explaining the whole thing in detail. There are three wires in total.

1) The red wire (connects to the top connector of the Secondary coil)

2) the Black wire (connects to the bottom connector of the Secondary coil)

3) The Blue wire ( latches onto the bottom part of a plastic hinge connecting to a metal connector)

A special thanks to TXW5CSM for his video on explaining the mystery of the blue wire.

There are grooves to hold the electrical assembly in place. Place it in gently and it should fit right in.

The red wire connection is pretty straight forward. Just connect it to the top connector of the Secondary coil. Make sure to route the wire from below the screw terminal, or the top plastic cover of the Dremel might damage it.

To connect the Black Wire, you'll need to lift up the Armature assembly. It's pretty straight forward after that. Just connect it and like the previous red wire, route the wire through the space beside the plastic screw terminal.

Now the tricky one. Connecting the blue wire. for this you'll first need to disconnect the metal terminal with the capacitor attached to it. Then gently place the blue wire's metal connector onto the plastic ledge just beneath. ( shown in the picture)

After that, route the wire through the space beside the plastic screw terminal and re-attach the metal terminal to the secondary coil.

Connect the power cord and slide the electrical assembly back into it's slot.

Now we're ready to put everything back together.

Place the Power Button Assembly in place. The small notch should place just on the switch ( as shown in the picture)

Attach the cover to the speed controller. It has notches to fit the PCB.

Place the speed controller in place. One end of the Power Button Assembly sits into the plastic knob of the Speed Controller.

Now to put it all back together and see if it runs :)

Make sure to plug in to a 110v source! (Not making the same mistake again) and see if any smoke comes out.

If everything went well, your Dremel should be as good as new :)

Here's a link to my google photos Album for the project, if you guys need it.