McClean: PlasmaPreen ORingReplacement

Overview

If you notice when using the Plasma Preen that you get plasma but it seems "locked" (i.e. you see a pink-purple glow but it is not moving) the problem could be that the antenna (fan at the top of the chamber) is no longer turning.

It is possible that the fan has stopped turning because the O-ring that is used as a pulley to turn it has worn down and snapped. This protocol will explain how to take the Plasma Preen apart and replace the pulley.

The broken pulley in this picture causes the antenna to stop rotating.

Materials

You will need the following to change the brushes in the lab roller drums:

• New O-Ring (#263 O-Ring)
• Philips head screwdriver
• Small flathead screwdriver
• Pliers or wrench

Protocol

• TURN OFF THE PLASMA PREEN AND UNPLUG EVERYTHING.

• You are only going to be dealing with the "microwave" part of the plasma preen, so unhook the tubing at the body of the microwave (see illustration). These should only be finger-tight, so you should not need a wrench. Remove the glass barrel reactor from inside of the Plasma Preen (don't forget this costs >$800 to replace, so put it in an uber safe spot). Move the Plasma Preen to a clear work space where you have plenty of room to get on all sides of it.

• Remove the black case of the microwave
  • You will need to remove the handle to the power regulator (see picture). This can be done using a small flat head screwdriver and loosening the two screws. Then use the pliers or the appropriate wrench to remove the nut holding the potentiometer to the case.
  • Remove the screws holding the case on. There are 5 screws on the back of the unit and one per each side (7 total, 5 silver, 2 black). There are 4 plastic brackets on top of the microwave that need to be removed. Place the screws and brackets in a beaker, or similar, so that you don't lose them.
  • Slide the case back and off

• Check the pulley. The pulley is quite obvious and is right at the top of the machine. If it is broken, it should be obvious (see picture).

• You will also need to remove the handle to the power regulator (see picture).

• Begin by removing the back cover of the roller drum. There are four screws to remove using the philips head screwdriver. Throw them into a beaker or something else so that they don't go rolling away.

• Once the screws are removed the cover should come off easily. Remove it gently so that you don't rip off the (green) grounding wire.

Green wire is grounded to the back cover. If you are careful you can work around it.

• Inside you will find the motor at the bottom, attached to the belt that drives the wheel.

• We need to loosen the motor by undoing the two screws that hold it to the casing. You will do this using the 7/16" wrench. See the pictures to locate the screws.

• Once the motor is loose, remove the belt. Find where the two brushes are located (see picture). The are directly across from each other and one is much easier to reach than the other. In fact, if you are lucky and only need to change the "front" one, you won't need to undo the motor from the housing. Use the flat-head screwdriver to remove the cap covering the brush.

This is one motor brush hidey-hole. There is another one directly opposite it at the back of the motor.

• Remove the old brush. If it is worn down, replace it with a new brush. Replace the cap.

The spring on the brush should pop out and make it very easy to remove the old brush.

• Replace the belt. Reattach the motor to the housing. Use the wrench to tighten the two screws holding the motor to the housing.

• Replace the back cover.

• Voila! If it was the brushes, your roller drum should roll once more.

Helpful Links

• What is a brush and why is it in a motor? How Stuff Works
• Lest you want to change the brushes on your washing machine's motor: Art of Doing Stuff's Explanation
• Manual for the TC-7: ‎ Roller Drum Manual

Notes

Please feel free to post comments, questions, or improvements to this protocol. Happy to have your input!

1. List troubleshooting tips here.
2. You can also link to FAQs/tips provided by other sources such as the manufacturer or other websites.
3. Anecdotal observations that might be of use to others can also be posted here.

Please sign your name to your note by adding '''*~~~~''': to the beginning of your tip.

*Megan N McClean 17:11, 7 May 2015 (EDT): This is a bit of a greasy job as you can see from my fingers in the above pictures. You might want to wear gloves. I preferred to just get greasy and then wash my hands, because it was easier for me to grab screws, etc without gloves on.

Contact

• Megan N McClean 14:01, 07 May 2015 (EDT)

or instead, discuss this protocol.