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Thread: ALC 68B advice

  1. #1
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    Default ALC 68B advice

    Hey guys;

    I've found another laser enthusiast here in Charleston! Gonna try and meet with him later today to talk lasers and see if he's interested in the SELEM this summer.

    However, I've also discovered that he's got a good bit of laser equipment that he's looking to sell. (He did shows out west for 7 years, but he says he's tired of the business and want's out.) Anyway, he has an air-cooled ALC 68B laser that he's thinking about selling.

    This is a medical laser that he modified to run CW for shows. (Apparently in it's original configuration it was designed to do 3-5 watts for several seconds, and then be off for several minutes.) He's got it set up to do around a watt continuous (all lines) while running off a dryer outlet plug. (Single phase 220v) He also added a couple large blowers to increase the cooling to the head and PSU.

    Now, my question is - how cantankerous are the 68B's? All the argon's I've owned to date have had sealed optics. This one does not. Is adjusting the mirrors something I'll need to do with any regularity? And if so, is this something I can learn to do myself without hosing the laser? Furthermore, are there any other "gotchas" that I should consider with respect to this laser?

    The main reason I'm interested is that this laser fits my budget and offers me an order of magnitude more power than anything else I've got. (Solid state is nice, but to get to a watt of power you've got to spend more money than I can afford right now.)

    But I don't want to buy this laser if it's going to be a pig to run, or if I stand a good chance of ruining it the first time I have to adjust it. I'm also concerned about the stability of the power supply.

    Comments?

  2. #2
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    Default

    well if yo dont like it... give it to me
    I got 220Volt in my House

  3. #3
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    Shipping it from Charleston to Norway might be a little expensive...

    I'm going to talk with this guy again tonight and see what I can learn about this laser. I've read a little about how you have to "walk" the mirrors on a laser like this, especially after cleaning, but I've never actually done it on an Argon before. I'm hoping that it isn't too hard to learn. (I'm also hoping tha the guy is willing to be reasonable with his prices!)

    If I get it, you folks will be the first to know about it.

    Adam

  4. #4
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    I have owned a couple of 68's, they are quite good lasers. For continuous use, nothing over 1.5W is recommended. Make sure you have a very good centrifugal fan for cooling. Set this up on the manifold and use it to extract air from the head. Use 2 of the H/D papst type fans for blowing air in. I usually only needed to adjust optice every 2 or 3 shows. If you have got the end plates set up well, this can be done by eye usung the correct size spanner. Only minute adjustments are required.

    Keep an eye on the large PSU reservoir caps, they can stsrt to wear, if in doubt replace them with ones of a slightly higher voltage. Expensive, but worth while. The passbank transistors can also blow. This can also get expensive. Luckily it only happened once in 5 years.

    It is also recommended to use an air compressor to blow out all the dust which accumulates on the heatsink vanes. Again, do this every 3 or 4 shows and all will be well. I used to do the same with the PSU as well, although this can be done less frequently.

    The 68 is a good choice for reasonable power without using water cooling. Have fun.

  5. #5
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    Quazar;

    Thanks for the info! This particular laser has two large cooling fans already installed, and running at 1 watt the outlet air temperature is around 130 degrees F. Good idea about using compressed air to keep the fins clean though - I should probably start doing that with my other, smaller argons as well.

    As for the optics adjustment, you make it sound easy! I guess with a prizm and my lasercheck wand I should be able to tweak it until I get the maximum output, but I've never walked-in a set of mirrors before. I know that the laser FAQ has a good bit of information about it, but I'm still a bit timid. So you don't think it's that hard to learn the process then?

    Also, what's the best way to clean the external mirrors? I'm thinking maybe lab-grade isopropyl alchohol and a lint-free tissue?

    RE: PSU caps... I'm assuming these are big honkin' electrolytics, right? And they dry out and fail? I can get pretty good prices on caps from Digikey, and I'm not afraid of a soldering iron, so if I do end up getting this laser I'll probably take your advice and swap them out with new ones...

    I should know something by next week, and if I get it I'll be sure to post the news here...

    Adam

  6. #6
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    Correct regarding the electrolytics. Replace with ones at least 50v higher, they will perform much better as they are operated quite near their limit.

    If you remove the optics for cleaning, you will have to re-aligh them afterwards. With regard to this, the 3 adjusterss form an "L" shape. Once set, NEVER adjust the centre one. Only use the 2 end ones for alignment. This will save lots of grief.

    Acetone is also good for cleaning optics, evaporates very quickly.

  7. #7
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    Well, I didn't get the laser. Got out-sniped at the last minute. Dream-Beamz wanted it a lot more than I did I guess! (I think he bought it as an investment though - he just sold a 68B a while back for like $2000, so my guess is that he's planning on flipping this laser soon.)

    I guess I'll keep looking...

    Adam

  8. #8
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    My bad, I accually made the last min bid with a last min notice. my friend that i bid on it for is keeping it. Its very well designed although you will be happy to hear that the output power sits at around a half watt at the same current my old one sat at a watt. But if it makes you sleep easier about it, this laser is being put to good garage hobby use and wont be sold as an investment

    Quote Originally Posted by Buffo
    Well, I didn't get the laser. Got out-sniped at the last minute. Dream-Beamz wanted it a lot more than I did I guess! (I think he bought it as an investment though - he just sold a 68B a while back for like $2000, so my guess is that he's planning on flipping this laser soon.)

    I guess I'll keep looking...

    Adam

  9. #9
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    AHHHHHHH!!!!!

    DreamBeamz... Damn - I never made the connection. I'd forgotten about that auction.

    Well, thanks for stepping forward anyway. And no - I don't hold a grudge. E-bay is a winner-take-all, looser-gets-nothing environment and we all know it.

    Glad to hear that the laser is at least being used by another hobbyist.

    I'm still looking for a decent deal on one for myself. I've missed out on two others on E-bay since that auction.

    BTW, the guy that sold you the one you bought didn't know a whole lot about it. My guess is that the mirrors are seriously out of adjustment, and the unit may need a good cleaning as well. Still, it sucks that you're only getting a half-watt out of it. Maybe with a little TLC the power will come up...

    Adam

  10. #10
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    i realigned it to get the 1/2 watt. I have owned a few HGMs and ALC68b's and c's. The tube is near its death although that was the cleanest hack i have ever seen done to an HGM, it still looked stock

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