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Wednesday, May 17, 2017

K40 Laser Tube Specifications, Maintenance, Failure & Replacement


A collection of information about laser tubes and their care.

Warning: run your laser with properly treated distilled water as a coolant.


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For other information on the K40-S build use the  K40-S BUILD INDEX with schematics

Laser tube operating conditions (Reci Laser):

  • Water cooling: using purified water; 2 to 5 liter/minute, (31GPH-80GPH)
  • Water temperature: 10-40℃, (50F - 104F)
  • The operating environment: temperature 2-40℃,(35.6F - 104F; humidity 10-60%.
  • The working current: test current is 29mA. The maximum working current is 29mA. The running current must be kept below 27mA. The life span can reach 8,000 hours if the current is kept below 25mA.
  • The ammeter must be connected to the negative electrode of the laser tube. When it is working under high current for the long term, the negative pole will appear light yellow and the life span will be shortened rapidly.
  • To protect dust from going into the insulation sheath, please wrap it with plastic film.

Laser Cooling and Condensation

Laser Tube Replacement

Tube Installation depends on the tube and there are multiple ways to connect to the pins on the tube. Pick your poison.

Basic Anode Connection Termination Methods

Unplug your laser from the mains power and let it sit for 1 hr.

Observe how the anode wire is connected to the tube including the wire routing and restraints.
Install the new anode wire in exactly the same way.

At the Anode end of the laser tube
  • Remove the silicone sheath from the anode connection. Minimize forces on the anode pin. It should pull off but if not you may have to cut it off.
  • Your anode wire may be twisted, screwed or soldered on the anode pin.
  • Remove or re-terminate the old anode wire. 
  • Replace the anode wire in the same way it was connected, twist, solder or screw.
    • If soldering, use minimal heat. Some recommend using Teflon tape to hold wires that are twisted see video below.
  • Route and restrain the wire in the same way. Usually, tie wraps around the tube moving away from the anode end toward the cathode end.
  • Flow silicon around the anode wire connection (use the white tube that came with your K40) 
  • Push the silicone tube over the wet silicon filling the tube. If you had to cut off the tube you will need to replace it with a piece of silicone tubing.
  • Add more silicon to the top of the silicon tube if needed
  • Let dry for 24hrs before using the machine
Alternate silicon: Permatex Blue RTV Gasket Maker. Available in auto and big box hardware stores.
703 adhesive silicone rubber insulation/potting/electronic waterproof sealant (the stuff that comes with the machine)

Other Methods

The videos below for removing a laser show connection and disconnection of the tube from its supply and can be used as a reference example:
  • Videos
  • Replacement Tidbits from the web:
    • "Disconnect power from unit!!
      Gently pull the existing silicone tube off the terminal post by gently twisting and pulling it along the wire itself.

      Use a soldering gun to heat the existing terminal post to gently release the existing wire connections. Then cut and clean up those wires. Also, clean out the silicone tube of the old residue. Of course, you need to remove the water connections and drain the tube. When installing the new tube keep the same orientation as the old tube and reconnect the water lines. Before attaching the power leads, screw down the retaining brackets and make sure the grounding wire is secured properly.

      Since you are replacing a tube, you already have a tube and terminal posts to practice on first. Make sure the wire leads are stripped at least 1/2" long, enough to be hand wrapped tightly around the protruding terminal post. The advantage of Rosin Core Solder is that it contains a built-in FLUX which helps to clean and bond.

      Before the wire strand is wrapped, make sure the silicone tube covering the wires is cleaned and placed back onto the wire. Once the wire strand is wrapped around the post, quickly heat and add some solder. Let it sit for a few seconds to cool and bond. The connection will be very secure. Just push the silicone tube back over the entire connection, completely fill the tube and connection with quick-drying silicone and in about 3 hours once the silicone drys, you are back in business."

Arching [needs content]

Reattaching the Water Jacket

Under shipping pressure or in the event the tube overheats the water jacket can become detached. 
Seems as if you can epoxy it back on! Check out this post.

Cleaning the laser tube water jacket

Replace all the water in reservoir with a couple of liters of vinegar and tap water... let it run for 12-24 hours replace all water with tap water only let it run for a bit... place outlet tube into a waste pan and flush adding a bit more tap water as your reservoir drains. Purge all water and replace with distilled water and some algaecide drops for aquariums. 

Laser Tube Specifications

Parallax: Laser Failure Modes and Warranty Info 

Enjoy and comment
Maker Don

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