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Thread: Spectra Physics 171 White Light Replacement Tube

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    Default Spectra Physics 171 White Light Replacement Tube

    Picked up a complete Spectra Physics 171 the other day. The head was nicely crated, but the last time it was likely run was sometime during the year of 2001. It is gas intact, had a slight water leak out of the bottom of water jacket which I repaired. I'm planning on testing it next week, but I'm skeptical as to whether it will light. If all does not go well, I'm assuming I will need a replacement tube or have this one refurbished. If anybody could recommend a company who does that or sells replacement tubes for the 171 that would be great. I'm also looking for a manual for the 171 and a 270 exciter.
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    Bring up the voltage real slow. Someone can tell you what the voltage across the tube should be at a given current. I do not know. That will tell you a lot about the tube. If your really lucky they can come back after sitting but it's not the norm. Good luck and talk to someone more knowledgeable then I am before turning it on. Check the supply before you use it. I didn't on one I had and blew the entire transistor stack. That was expensive. Also have a water leak. Very impressive smoke.

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    Thanks kecked, I appreciate the tips. This laser is a beauty, the bigger brother of the 168. I'm very happy to have it.

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    Congrats ! ...Your side of the pond ....for replacement sources and info in general . you should really talk to stateside gasguru, Steve (Mixedgas), I think refurbished tubes are still available in Europe, but that's not much use to you in the states.

    Cheers

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    Call Brian Bohen at Cambridge Lasers Labs and get a PDF of the manual. Cambridge owns the rights to the tube design. Don't power it up, let alone start it without READING the manual cover to cover at least ten times. Correct current knob setting for start is half to three quarters of full power setting, not down at idle. . If you have one of the rare psus with variable magnet , the starting magnet setting is at least one half rotation ie 12 'Oclock noon or higher.
    ~
    Why read the manual? You will only want to be in the room with a 45 amp Plasma oscillation Once, if ever at all.
    ~
    The cost for a refurb tube will still shock you, let alone for a white light.. Think beat up, used, Porsche.. There is still some scientific demand for the tubes, and a few laser show companies that project long throw on mountains still use 171s.
    ~
    Its been 15 years since I've used one, and probably seven since I've been it the room with one working, but I would still read it cover to cover.. Things like older ones develop ozone in the intracavity space that can lower output power (carefully filtered purge gas needed for full power) , frying dust/fingerprints on the windows, not getting fingerprintgs on the intra-cavity catalysts, using the search bar properly, how to remove the window covers, things like that.
    ~
    A passbank passive check is probably a good idea, too. Taking out seven or ten passbank transistors or more all at once is really easy. That is why you never start one down at Idle.
    ~
    The importance of a pair of safety glasses, never looking anywhere down the bore, and a great beam stop with side glow suppression cannot be over emphasized. Especially if it does not start right away.
    ~
    Your odds are one in a gazillion of it starting.. Your odds of troubleshooting a passbank with out insight from training, and a big bench DC power supply, not good. Good Luck..
    ~
    Steve
    Last edited by mixedgas; 08-21-2017 at 06:27.
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    Thanks for the information Steve. I have a nicely running 168 in my office right now. They look similar, but I think that is deceiving. I repaired the leak from the water jacket with JB weld. Had a slight problem with the flow switch/impeller inside the power supply. The water flow interlock is not activating. I'm thinking of jumpering the flow switch terminals and tying in a manual flow meter and needle valve upstream so my flow rate is right. Opened up the PS today and all fuses are good. Passbank looks nice and clean, no water leaks or charring anywhere.

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    Flow should be as much as the plumbing can sustain, but do not exceed 60 pSI backpressure unless you like the over
    pressure dump valve opening. No need to limit flow.. Cooler is BETTER. Especially on the 171.. I would not throttle it to the exact specification, I would exceed the spec if at all possible.
    !

    I get weary when folks bypass the flow switch, had a student do that at work when I was not there one day, in the early 2000's that resulted in a 7500$ problem.
    Proteus flow parts are cheap if you keep looking. The flow rotors are replaceable/interchangeable with care, and usually that is all that wears out. Anecdotally I think there are a fast rotor and a slow rotor type, depending on which used Proteus you get on Ebay. The hole in the back of the rotor wears to become oblong, and the rotor stalls. If you get the slow one, you recalibrate the adjustment pot on the LM2917 (??) chip.
    ~

    271 PSU topology is a bit different then the 265, they act quite a bit different. You need to check the 271's transistors and fuses with a voltmeter. There is a nice procedure for using a 19" rack style adjustable DC supply for testing the passbank, too. With the right cheap voltmeter on a modest 10K or 2K resistance setting, the transistors look like two back to back silicon diodes. Shorted passbank transistors are common, and show up as 10 Ohm or so shorts, shorted C to E or B to E...
    !
    PM Bradstockdale here, he just got the cleanest copy of the Schematic and manual I have ever seen, since Sea World in 1988... He might scan it for you. The folks at Peachtree laser might just know something about 171s if they are still around. If I remember right Stone Mountain are Coherent large frame fans..
    !
    Steve
    Last edited by mixedgas; 08-22-2017 at 11:07.
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    I think dale has two in his basement

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    Quote Originally Posted by MrNIFty923 View Post
    ..I repaired the leak from the water jacket with JB weld. Had a slight problem with the flow switch/impeller inside the power supply. The water flow interlock is not activating. ..
    OK, so.. continuing from the email / for the info-benefit of others, here's some food for thought (...from a 171-owner who learned this info the 'hard way' - namely, a $12,000. tube exploding in his face... +_+

    a) I would Not, repeat, Not rely on a 'JB weld repair', especially long-term.. For one thing, that may 'soften' under the heat-load of the water (...and if it's where I think it is, based on what you said, that Is the 'hot side', and that area is a notorious leaky-spot..) and, even if it does not, it might give up the ghost under the heat + Pressure.. Remember, you're gonna need to feed this 80psi, just to satisfy the Interlock / kick-off the 'water light', so.. Really, overall the Best repair for that area is the OEM O-ring (which, again, I have plenty of..) and a nice, careful cleaning / reassembly of that water-block / fitting...

    b) Backing up what P'fesser Steve is saying, Don't (imho.. 'bypass' the Proteus / use something else.. That, as a flow-sensor is chosen / spec'd for a reason, and part of it has to do with 'reaction time', if your water flow stops suddenly, etc.. Also, Proteus cannot be 'jammed' (by, say, some 'flotsam' that some-crazy-how gets thru your filter / into the PS, etc..) in the 'flow OK' position, as other-types can, so.. Best to simply determine what exact model you Have, and replace - if necessary.. IIRC, those used a 'Series 100' (?) http://proteusind.com/product/100-se...w-switch/..You can checkit yerself / search that up on their site / spec sheet, etc, and let me know if you need parts, etc..

    c) ..and on that same topic (Proteus parts..) as I mentioned in the email, best to - first - CHECK THE COIL... If it's dead (..and they Do die / 'go bad', especially the 'resin potted' ones..) no amount of cleaning will ever pass the 'flow OK signal' (..and thus not knowing it was the coil all along, you might be tempted to 'up the pressure' / flow, and that - could - result in a KaPow of your beautiful glass bell there, and then, ya know... lots of tears / screaming / cussing, etc, etc..

    ..Then, sure - Go ahead and Clean the rotor / spindle / cover plate and the base, there (just remove the electronics-base, of course.. with "CLR".. just let it soak in a small bowl of it, overnite, then wash / rinse all trace of it off, before reassembly... BUT, STILL - BEFORE YOU TRY AND GO TO FULL PRESSURE:

    d) ..Even If this system was formerly used in some 'lab enviro', with a closed-loop and/or super-filtered, super clean water supply, you should strongly consider running 'CLR' thru the Entire system - PSU / passbank / water I/O underbelly / tube, and all - BEFORE you get it up to 'full pressure' / flow AND Start the puppy, because, even though you might see 'clearish water' coming out the drain when you first flow water thru it, once you've got it Lit, and everything starts heating up / expanding, if you Don't do a 'CLR-flush / deep clean', first, I've seen it happen where some 'intratube' / piping-skak ends up dislodging / getting thru the system - which is Past the input / house-water filter (since it's 'coming from within'..) - and IF that skak ends up piling up / stopping drainage? You can - quicker than the overpressure valve can 'react' (especially if it's calcified-closed..) - end up with an exploded tube.. and water spraying out of it everywhere.. (..and a Lit tube with 600VDC across it, getting sprayed down by 6 gpm of water @ 80 psi is Not a good way to start your day, Trust me on that one..

    ..You can fill it with CLR via a small 'leader hosen' and funnel, and use a gentle-pressure air pump to work that thru the entire water-chain / tube, until it's coming out the drain.. Let it sit overnight - flush w/ clean water Super-well.. and 'rinse / repeat', untill After a CLR-flush, the water in the tube looks nice and clear.. You'll (likely..) be *blown away* at how much 'calci-skak' shows up in the tube, from what you thought was a 'nice clean system' internally, Especially with a tube / PSU this old..

    e) Impressed you were able to source enough 480 for this badboy!.. Not an easy task, these days...

    Anyhoo, Fwiw..
    j

    ....and armed only with his trusty 21 Zorgawatt KTiOPO4...

  10. #10
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    Brad's had a dead tube, maybe he'd part with the magnet... Then maybe not...

    Steve
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