Thursday, June 9, 2011

Lamp and Lamp Wiring Harness Disassembly

If you are not planning on doing a complete restoration of your sewing machine then you probably don’t have to do all the steps I’ve shown below.  However, for safety reasons, you do need to inspect the wiring connections on your machine to make sure they are in good shape.  At a minimum, check the wiring on the 3 pin terminal (Step 2) and the socket (Step 5).
Here are the steps that were required to remove the lamp assembly from Ms. Rusty.
  1. Removed the sewing machine (Ms. Rusty) from the cabinet by removing two set screws from the underside of the machine base.
  2. Removed the 3-pin terminal by removing the screw attaching it to the head (machine body).  I then labeled and disconnected each of the wires. 
    • Here is a picture of the 3-pin terminal after it has been removed. 1 - 3pin terminal with switch
    • Here is a picture of the terminal bracket after removal.5 - terminal bracket
    • Here is a picture of the labeled wires after the 3-pin terminal and bracket have been removed.
      • Purple Tape = Pin 3 = Red wires: light and to motor
      • Orange Tape = Pin 2 = Black wires: motor & foot controller
      • Blue Tape = Pin 1 = Yellow wires: light & foot controller
        4 -Tagged Wiring 
  3. I then removed the light switch from the 3 pin terminal by removing the knurled thumb nut and hex nut from the front of the switch. I then disconnected the light lead wire from the switch that is attached at the screw and labeled it with green tape. 
    • Here is a photo of the switch out of the terminal and with the light lead wire removed.  The wire that is still attached has been soldered on and I don’t plan on removing that right now.
    3 - Light switch assembly
  4. Removal of the bulb and lamp shade:  Push and twist the bulb to release it from it’s housing.  You can then access the small screw on the lamp shade that attaches it to the machine body.  Once that is off you can access the set screw at the back of the shade to disconnect the shade from the wiring harness.
    • This photo shows the disconnected lamp shade and the screw that attaches it to the machine body (head).8 - Lamp shade, front
    • This photo shows the set screw at the back of the lamp shade7 - Lamp shade, back
  5. Depending on your luck, the felt pad covering the back of the light assembly may either be in the lamp shade, fallen to the table, or still on the back of the light socket.  Mine was still attached to the socket and without the Adjusters manual I wouldn’t have noticed that it was hiding two screws.  After you remove those two little screws your wiring harness is now free!  Well, almost – see step 8
    • These photos show the felt covering the socket, the back cover removed from the socket (wires exposed), and the socket removed from the wires.9 - Light socket & felt washer10 - Light socket without cap11 - Disassembled light socket, top view12 - Disassembled light socket, side view
  6. Then, according to the Adjusters Manual you need to remove the stitch indicator plate to see how the light leads are positioned inside the machine head
    • Front and back photos of the cover plate and washer14 - Stitch Indicator Plate & Washer - Front15 - Stitch Indicator Plate & Washer - Back
    • After removal of the cover plate and after removal of the washer13 - Behind stich indicator plate16 - View behind stitch indicator plate with light leads in place
  7. I then took photos of where this wire harness snaked through the machine
    • It makes 2 bends – 1 near the stich indicator plate and 1 near the bed17 - Light wire lead location in head18 - Wire clamp view from underside of machine
  8. The next step was removing the set screw holding the light lead clamp.  Let me tell you that little bugger was hard to find because it was so covered in crud!
    • The colored end of the toothpick is showing where the set screw is located19 - Clamp Set screw location20 - Closeup of clamp set screw
  9. After the set screw was loose, then it was relatively simple to pull out the lamp wire harness.
    • Photo of the wiring harness outside and in front of the of the head21 - Lamp wire assembly removed
    • Both lamp wires inside the harness and clamp22 - Lamp wire assembly
    • One of the wires removed from the harness23 - Yellow lamp wire from assembly
Initially I thought the lamp wires were in good shape, but upon closer inspection I noticed that they are rusted and starting to break off near the ends.  As a precaution, I have decided to replace all the lamp wiring in Ms. Rusty.  I’d rather be safe and confident the wiring is good and not have to go through this whole disassembly process again in the future.

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