Page 1 of 2 12 LastLast
Results 1 to 10 of 11

Thread: HGM K7 Light Controller Repair - Need Advice

  1. #1
    Join Date
    Jun 2008
    Location
    Orange County, CA
    Posts
    205

    Default HGM K7 Light Controller Repair - Need Advice

    I need some help from the smart people in the PL family.

    Several months ago I brought home a fully operational HGM K7:

    http://www.photonlexicon.com/forums/...?highlight=HGM

    I modified the fiber output housing by removing the collimating lens.

    This weekend, the front display was flashing a low power warning when I set the output to 5+ watts.

    I then noticed artifacts in the output beam. So, I removed the fiber output housing and found that the plastic around the internal beam splitter was melted. I guess when I removed and re-installed the fiber output housing it was partially in the output beam.

    The following pictures show the housing where I removed the beam splitter. The beam splitter was melted into the plastic housing and was destroyed when I removed it.

    Click image for larger version. 

Name:	HGM K7 002.jpg 
Views:	6 
Size:	1.54 MB 
ID:	43350....Click image for larger version. 

Name:	HGM K7 021.jpg 
Views:	8 
Size:	2.00 MB 
ID:	43349....Click image for larger version. 

Name:	HGM K7 020.jpg 
Views:	5 
Size:	1.98 MB 
ID:	43348

    The laser still works, but now it is at full output and no way to control the power.

    I have a couple of ideas to fix this problem:

    1) Find a suitable replacement beam splitter. I have a milling machine and I would need to re-machine a 45 degree shelf on the plastic housing.

    2) Couple a “grain-of-wheat” light bulb to the photo-diode and control the beam power by dimming or brightening the light bulb.

    3) Replace the photo-diode with some sort of variable voltage source.

    I am tending towards replacing the beam splitter, but I do not know if the beam splitter is a special coated optic or if I could just use a glass microscope slide cover.

    Please recommend some solutions and/or what to use for the replacement beam splitter.

    Thank you!

    Willie

  2. #2
    mixedgas's Avatar
    mixedgas is offline Creaky Old Award Winning Bastard Technologist
    Infinitus Excellentia Ion Laser Dominatus
    Join Date
    May 2007
    Location
    A lab with some dripping water on the floor.
    Posts
    9,025

    Default

    It is a specially coated piece of glass, coated for about 1% reflection. Do not try to inject another light source, or the PSU will oscillate and the plasma tube will die. You need the light feedback to prevent the plasma tube from oscillating. You also need it because there is no true upper current limit on the K7 PSU. Unlike the other HGM psus, the traditional hack of using the upper current limit to run the tube CW with the computer disconnected does not work on the Surgica K7. In other words, if there is no feedback, the PSU will damage the tube eventually.

    There is only one guy in the US who normally has that whole HGM assembly in stock, and he's been very, very, grumpy towards hobbyists lately. HGM and American Laser were both part of Laser Corporation and they shared certain parts and tubes. One shared part is the splitter plate. Your best bet is to find the beam splitter plate from a dead ALC 60X, Omni 532, HGM5 or HGM8. You may have to cut the glass to size, but it will be the same coating.

    There will most likely be a stack of black glass filters and diffusers between the silicon cell and the beamsplitter pickoff, calibrated for that particular laser. don't lose it or change it.

    Steve
    Last edited by mixedgas; 05-27-2014 at 05:49.
    Qui habet Christos, habet Vitam!
    I should have rented the space under my name for advertising.
    When I still could have...

  3. #3
    Join Date
    Jun 2008
    Location
    Orange County, CA
    Posts
    205

    Default

    Steve, thank you for your reply.

    Anyone out there with a dead American Laser or Omnichrome laser that they are willing to sell parts?

  4. #4
    Join Date
    Jan 2006
    Location
    Charleston, SC
    Posts
    2,147,488,525

    Default

    Not sure if it will help you or not, but I have an HGM Spectrum Argon that has a dead tube in it just taking up space in my garage. If you need parts from it, I'd be happy to send them to you for no more than the cost of shipping.

    Steve, you know the laser I'm talking about. Anything on that thing that would help out our friend Turbohead with his K7?

    Adam

  5. #5
    mixedgas's Avatar
    mixedgas is offline Creaky Old Award Winning Bastard Technologist
    Infinitus Excellentia Ion Laser Dominatus
    Join Date
    May 2007
    Location
    A lab with some dripping water on the floor.
    Posts
    9,025

    Default

    Quote Originally Posted by buffo View Post
    Not sure if it will help you or not, but I have an HGM Spectrum Argon that has a dead tube in it just taking up space in my garage. If you need parts from it, I'd be happy to send them to you for no more than the cost of shipping.

    Steve, you know the laser I'm talking about. Anything on that thing that would help out our friend Turbohead with his K7?

    Adam
    Yeah, the fiberfeeds are probably interchangeable.

    Steve
    Qui habet Christos, habet Vitam!
    I should have rented the space under my name for advertising.
    When I still could have...

  6. #6
    Join Date
    Jan 2006
    Location
    Charleston, SC
    Posts
    2,147,488,525

    Default

    OK - let me dig into the case and see what's still in there.

    Worst case, I know I have the original fiber feed from my HGM-20 that I could send him too.

    Adam

  7. #7
    Join Date
    Jun 2008
    Location
    Orange County, CA
    Posts
    205

    Default

    Adam, your offer is very generous. I am certainly willing to pay the shipping and handling cost. Let me know if you have the part and I will PM you with my address. Thank you.

    Willie

  8. #8
    Join Date
    Jan 2006
    Location
    Charleston, SC
    Posts
    2,147,488,525

    Default

    I'm working late again today, but tomorrow I should have time to get into the garage and take some pictures of the unit. Then we'll see what Steve says!

    Adam

  9. #9
    Join Date
    Jan 2006
    Location
    Charleston, SC
    Posts
    2,147,488,525

    Smile

    OK, I finally got some time to look in the garage and get some pictures of the output end of my HGM Spectrum. The tube is dead, and the fiber-launch hardware is of no use to me, so I have no problem stripping it for parts, but I have no idea if it's the same as what is used on the K7.

    Here are some pictures I took:





    Click on either picture to see it in full resolution.

    So, what do you think Steve? Will this work on a K7? Looks like it would be easy enough to take it off and drop it in the mail...

    Adam

  10. #10
    Join Date
    Jun 2008
    Location
    Orange County, CA
    Posts
    205

    Default

    Adam, thank you for going through the trouble of taking and posting pictures.

    The mount appears to be physically identical. The circuit board is different, however I would replace it with the board from my K7.

    Can you please send me the fiber mount?

    I will PM you with my address.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •