Saturday, 17 December 2011

How to Re-wire a Potted Motor, Part 7: Disconnecting the Motor Leads


Okay folks, time for us to get our hands on the machine.

Before removing the motor from your 201-2 or 15-91, we must first disconnect the motor leads. From here on in we’re going to need lots of different screwdriver bits, so be sure to read the entries on proper screwdriver bits if you’re unclear on this area; if you use the wrong type of driver and strip a screw in the middle of a motor re-wire, you’ll find it a huge hassle.

Step one is unplug the machine. Not at the wall, but at the terminal body.



Step two is to remove the single screw holding the terminal body on. (A Brownells bit #270-5 fits perfectly.) You’ll find this screw has often been overtightened, so remember to press hard into the screw as you unscrew it, to reduce the chances of strippage. After you’ve removed the screw, keep it safe, we’ll need it again in a sec.


Gently pull the terminal body towards you and downwards. Now at this point you’re going to see one of two things:

Best-Case Scenario:

If you see this, you're lucky.

I call this the Best Case Scenario because even though we can see some exposed wire that needs to be replaced, everything is still clean and there is no oil damage. Which leads me to the next example….


Worst-Case Scenario:


If you see this, you're unlucky. But don't despair, we'll get to it.

This is a different machine than in the previous photo, and as you can see, we’ve got big problems. Never mind the exposed wiring and cracked, rotted insulation--there is massive oil damage. Someone has over-oiled this machine, causing the wiring insulation to get oily and melt and run into the terminal body. Look at how the light switch on the left is covered in thick, black, hardened goop.

Although this problem is fixable, this is a LOT more work than the Best-Case Scenario, and will require a separate series of entries. If your machine’s terminal body looks like this one, let me know in the comments and I’ll begin preparing that Worst-Case Scenario series of entries. In the meanwhile I’ll continue on here for the Best-Case Scenario machines.

Unwire the terminal body

Remove the three thumbscrews from the terminal body. There are only two motor leads, but we remove all three thumbscrews because the wires are often covering one another.



Next, gently pull the ring connectors off of the brass studs. You may want to mark the wires with tape, according to what color they connect with (red, black or yellow.) And be vigilant--there may or may not be a brass washer on top of the ring connectors, and if you pull them up too fast, the washer may go flying off into space. It’s happened to me and I never saw that washer again.

Gently pull the rings off of the brass studs...

...but keep your eyes open for these washers!

Next, isolate the two motor leads--the two wires leading up to the motor--and pull them gently to the side. They may be plastered against the side of the machine, but don’t be shy about pulling them off; if the machine needs re-wiring, then these wires have to go, no matter what.
 

Rewire the terminal body

After isolating the motor leads, re-connect the other, non-motor wiring. Then screw the thumbscrews back in place.

Put it back together, minus the motor leads

Next, screw the terminal body back into the machine. Not tightly, just enough to keep it in place.
We do this partly for safekeeping--there’s no chance you’re going to lose the thumbscrews, brass washers, etc. if they’re attached to the machine--and partly to keep it out of the way: The next step will expose some potentially messy grease, and we don’t want that getting onto the inside of the terminal body.
  
Nice and tidy, in preparation for the next step

Go on to Part 8: Removing the Motor Housing

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