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Thread: So,,,I went and did "IT",,,

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    Default So,,,I went and did "IT",,,

    First things first,howdy to all,it's been awhile since I've posted here,mostly for lack of time. So I got rid of all my Argon heads,tubes,power supplies and what-nots a couple years ago,,,but for 2 Uniphase 2113-75 power supplies. Well I just happened to find 2 2213-75 heads at a good price on,wait for it,,,E-Bay of all places!
    Imagine my excitement! 55 bucks each + shipping on my employers Fed-Ex account,for a total of 110.00 out of pocket to me.
    Well found a couple EBM fans,duct at Home Depot,roll of Duct tape and we're in business,at least one is.
    1 head does over 80mw at 10 amps and other head just ticks with a twitch of blue like "Timmer" on Southpark. The head doesn't seem to get warm either,even without the fan running,broken filament? I've checked voltage to the tube and appears to be 3-4vac with either ps.
    Gentlemen,start your prognoseses?
    Mike

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    Try testing current on the primary side of the heater transformer... That should tell you if there's a load on it or not. (Direct test of secondary current might be too high for most meters to take).

    Blue twitching is probably a good sign, means the gas is likely good, and the ignitor too. No warmth at all maybe isn't, you may be right that the heater is broken.

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    Quote Originally Posted by The_Doctor View Post
    Try testing current on the primary side of the heater transformer... That should tell you if there's a load on it or not. (Direct test of secondary current might be too high for most meters to take).

    Blue twitching is probably a good sign, means the gas is likely good, and the ignitor too. No warmth at all maybe isn't, you may be right that the heater is broken.
    No No No No No yes yes.

    Great theoretical answer, but not the way to do it in practice.


    There is no reason to dig into the PSU. Especially not some of the newer PSUs that have switch mode cathode supplies. This is a hot chassis set, meaning it uses directly rectified line. Sticking a voltmeter where it does not belong can result in sparks. If you have a Ampclamp you can measure the secondary current. It would be equal to 50-75 watts when you do the math, depending if its a 2.6 or 3.2 volt cathode.

    There are two ways to check the cathode in practice.

    1. Easiest. Power down the laser, disconnect the head, find the two pairs of heavy wires they use for the cathode, which are usually yellow or orange, and see if you have a direct short across them with a Ohm meter. When the cathode is cold it has nearly zero resistance. Usually Sam has the pinouts in the FAQ.

    If its a circular connector, the cathode will be the ones on the two "large blade pins". If its the rectangular Molex style connector, you'll see pairs of heavy gauge wires, for a total of four conductors. They use two wires for each end of the cathode to make the cable more flexible.

    2. But the easier way is to hold a white paper card at the end of the tube and look for the cathode glow in the dark. It will show up as a dim, fuzzy, orange spot through the output optic. On a cylindrical head you may need to pull the rear cover to see the glow, depending which end they placed the cathode on. However you mush ensure there is cooling air at all times. If you can view it off axis, you'd see a orange spiral in there.

    The purpose of the paper card is to diffuse the light for eye safety reasons. Obviously looking down the bore of a laser trying to ignite is a bad thing.

    Do you get a flash of plasma or a flash of laser with the "ticks?"

    Steve
    Last edited by mixedgas; 02-18-2014 at 04:54.
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    Ok. I assumed with the history of past ownership this might be safe, but amp clamp is best. I just thought not all would have one. An ammeter wired in securely before switching any power is ok, but I could have spelled that out for safety, always wise to use a cheap meter and no personal contact just in case. When I measure mains amps it's never a casual probe-it-and-see so I have a habit of thinking other tech-heads might do it the same way.

    The fuzzy glow is a nice trick. I wasn't sure if it would show up through a cavity mirror so I didn't consider that.

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    Thank you Sirs,update,hooked it up and it does produce the orangeish glow inside,enable tube current on the interfae and after the delay it trys to start,tick tick tick with a blue dot on the wall/paper. Does not lase nor will the 2500 interface let me increase tube current,assumingly due to lack of lase current? The dot/beam is sharp and well defined,visibly appearing as bright as an idle beam would be comparing to it's twin. If necessary I can bring home my ind. ammeter tomorrow to see how much current the filiment is drawing. The first time I tried it was at work and obviously didn't notice the glow,I'll blame it on plant lighting or rushing after a 14hr day.
    Next step?
    Mike

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    Quote Originally Posted by HD58PHD View Post
    Thank you Sirs,update,hooked it up and it does produce the orangeish glow inside,enable tube current on the interfae and after the delay it trys to start,tick tick tick with a blue dot on the wall/paper. Does not lase nor will the 2500 interface let me increase tube current,assumingly due to lack of lase current? The dot/beam is sharp and well defined,visibly appearing as bright as an idle beam would be comparing to it's twin. If necessary I can bring home my ind. ammeter tomorrow to see how much current the filiment is drawing. The first time I tried it was at work and obviously didn't notice the glow,I'll blame it on plant lighting or rushing after a 14hr day.
    Next step?
    Mike
    Is there a continuous purple plasma glow with the orange after the first few ignite spikes? if the Cathode is glowing its good, no need to measure that. Next step, and I need to think about how to do it on that model, is to see if there is DC across the tube. The problem is tbe 15-20 Kv ignite spike makes that a interesting measurement that will kill your voltmeter.
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    JDSu psus are not easy to diagnose. I need to think how to do the next step. Usually I disconnect the igniter, but that is not so easy on this model. You can put the good head on the nonfiring psu with little fear . I would not put the bad head on the good psu however .

    Steve

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    HV resistor and little neon bulb? It would flash with ignitor pulses, but stay steady with the DC voltage. A few diacs in series might set thresholds for crude voltage detection in steps of 35V or so beyond the neon's initial threshold of about 70V. It's crude but might be good enough to detect a fault.

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    [QUOTE=The_Doctor;286258]HV resistor and little neon bulb? It would flash with ignitor pulses, but stay steady with the DC ,,,,,,,,,,,

    Thats great if you work with HV for a living and know how to insulate the throwaway voltmeter . Not many do .

    No, He needs a pin pulling tool to remove the ignitor pin. Problem is the "personality" board in the psu will see the missing ignite pulse and time out.

    Take the known working, lasing , head and place it on the PSU that is not firing to full plasma. Working Heads are very difficult to kill. If the known good head works, its either the light sensor is dead or the tube likely has one of four possible fatal issues.

    If the known working head does not fire, its a interface configuration issue or a dead psu.

    Do not leave the ignitor banging away on the laser if the tube does not light.
    A few minutes max if it does not light.

    Steve
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    Thanks guys,not sure if I explained my problem clearly. The "good" head (hereinafter referred to as "Head1") works with either power supply,no problem,it's "Head2" that won't start with either power supply. I will try it on both power supplies again to confirm and post again.
    Mike

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