ILT 5500A Questions and Help

[onelightmind]

Please excuse my lack of knowledge...

I own an an ILT 5500A capable of putting out 500mw but is only putting out 100mw due to cathode sag in the beam path. It is $1500 to rebuild with the new "non sag" improved cathode. Is there a less expensive way to fix it? I was thinking of running it and using a magnet to help bend the cathode back or???? Have not been able to find a schematic on this laser so don't know much. I sent it off to the shop so I do not have it here to take apart... Thanks

[DZ]

If you can, rotate the tube 180 degrees so the cathode will start to sag the other way. I had a couple 5490's years ago and I seem to remember being able to turn those, not sure about the 5500 though.

[mixedgas]

yeah, you can try rotating the tube, but until you correct the incorrect cathode voltage, in this case too low, it will keep sagging. So you would have to rotate the tube and then once its clear, IF it clears, get the voltage back up a half a volt or so, and thats if the transformer has taps.

With that model of ILT, the main optical alignment is inside, so its a pain in the neck if you loose alignment. The cathode is AC, so a magnet is out, and DONT let anybody try to tell you to overvolt it with a car battery either.


Did you try Evergreen for a quote?

Steve

[onelightmind]

Currently the laser is here http://dzlaser.com/ I DID loose alignment and it was a super pain in my ass. Rotating the tube sounds like a great solution if it is possible. I will have to ask those guys if they can do it for me. Gotta make sure they go the full 180deg so they don't throw off the polarization on my NEOS PCOAM in my little white system...Ihave a question about my NEOS but I think I should start another thread...

I have not checked with anyone else about the rebuild. DZlaser usually does it for $2500.00 but they are giving me a break at $1500.00 for a complete rebuild which includes the tube being back to original specs 500mw min output newly desgned cathode to spread heat more evenly, regass ect. 1yr warranty 200 hr tube life at full power. They are former employees of ILT.

The laser is doing 100mw now...guess I'll shoot off an email.

[onelightmind]

"until you correct the incorrect cathode voltage, in this case too low, it will keep sagging. So you would have to rotate the tube and then once its clear, IF it clears, get the voltage back up a half a volt or so, and thats if the transformer has taps."

Please explain the low cathode voltage making the cathode sag...

The guys at DZlaser said those cathodes tended to sag due to how they were designed.

Thanks for all you guys help!!

[mixedgas]

[QUOTE=onelightmind;90900]"until you correct the incorrect cathode voltage, in this case too low, it will keep sagging. So you would have to rotate the tube and then once its clear, IF it clears, get the voltage back up a half a volt or so, and thats if the transformer has taps."

Please explain the low cathode voltage making the cathode sag...

The guys at DZlaser said those cathodes tended to sag due to how they were designed.


Tungsten gets butter soft at 700'c , then at 800'C it gets hard, and then at 1130'c where it runs, its damn tough. So the idea is to pass through the soft zone on warm up as fast as you can. Plasma cools the cathode, so if the emission is down, and the voltage is down, and the current is high, they can get weak

On some older lasers, notably lexels, the weld to the tungsten from the kovar in the lead through seal is done with a moly or nickel rod, and this can diffuse into the other metal over time, weakening it, resulting in a bend in the assembly.

Now you know the Rest of the Story ,Good Day! (RIP Paul Harvey)

Steve

[onelightmind]

Thanks for the answer. Tungsten has some interesting properties huh.

[mixedgas]

Thanks for the answer. Tungsten has some interesting properties huh.

yeah, but only half the number of phase states of plutionium. :-(

Steve

[dhg6]

I have a water cooked ilt 5500a-wl it is water cooled and capable of 1.5 watts. My trouble it starts up very easy runs for three seconds then shuts down. I have tried lowering the output all the way down from 1.5W to 200mw but it still shuts down. The curtis meter shows 250 hours. All interlocks flow sensor and thermal sensor on the tube are working and again I hve more than adaquit water flow. Does anybody in the forum have a clue what may be causing the shut down. I'm stumped. Thanks in advance.

[mixedgas]

I have a water cooked ilt 5500a-wl it is water cooled and capable of 1.5 watts. My trouble it starts up very easy runs for three seconds then shuts down. I have tried lowering the output all the way down from 1.5W to 200mw but it still shuts down. The curtis meter shows 250 hours. All interlocks flow sensor and thermal sensor on the tube are working and again I hve more than adaquit water flow. Does anybody in the forum have a clue what may be causing the shut down. I'm stumped. Thanks in advance.

On most lasers that means you have a shorted passbank transistor or rectifier.

Steve

[Stoney3K]

On most lasers that means you have a shorted passbank transistor or rectifier.

Steve

That would be the case, were it not the 5500 supply is a switch-mode.

If there's a short on one of the transistors of the switcher PSU, the laser wouldn't run at all and would probably blow a fuse.

[dhg6]

Thanks for the thought but there is absolutly nothing wrong on the power supply side. Any other ideas? Thanks in advance.

[Stoney3K]

Thanks for the thought but there is absolutly nothing wrong on the power supply side. Any other ideas? Thanks in advance.

Have you checked the tube temperature with a thermometer and cross-referenced it with the temperature sensor's output, to make sure the calibration is not out of whack?

Also, the PSU is not getting too hot either?

BTW, the 5500A-WL is a rare beast. And I mean, really, really rare, even more so than something like a Reliant 300WL. Do you have the version with argon fill or with anything else like krypton or even mixed gas?

[dhg6]

No fans are running and the kicker is this supply will work on another one of my ilt's. But it was matched to this head now as a set for dental curing. Ilt's power control adjustments are all done on a tiny 20 turn power control pot on the head.

[mixedgas]

No fans are running and the kicker is this supply will work on another one of my ilt's. But it was matched to this head now as a set for dental curing. Ilt's power control adjustments are all done on a tiny 20 turn power control pot on the head.

If its not the PSU, if its not any matching done in the light cards or other little possible pots in the head (only used on some systems) its the gas pressure. Give the light card and light pickoff a good checking over. Also some ILTs have sensors for cooling in the head that need to match or it shuts down, for example, on air cooleds, they sense fan current, and some newer fans move more air but do not draw enough current.

Check the magnet current, check the cathode watts,check the head electronics, look for coolent flow issues in the head, but if its not that, its most likely low gas pressure.

Steve

[Stoney3K]

Check the magnet current, check the cathode watts,check the head electronics, look for coolent flow issues in the head, but if its not that, its most likely low gas pressure.

Steve

But if the gas pressure is too low, it will either not start or have trouble starting, or run for a very short while and then 'sputter out', right?

As dhg6 explains the problem, the tube has no trouble starting and running steady state even at full bore current, but suddenly shuts down as if it were deliberately switched off.

If the supply is from another (air cooled) ILT, it may just shut off because it doesn't sense any fans running. Obviously, on a water cooled head, there aren't a lot of fans to speak of, so the PSU would shut down because it's intended to do so.

You can always try wiring a few dummy fans to their respective pins and see if that keeps the head going.

[mixedgas]

[QUOTE=Stoney3K;219071]But if the gas pressure is too low, it will either not start or have trouble starting, or run for a very short while and then 'sputter out', right?

If it runs for about 3 seconds and dies, and the supply is fine, it can have low gas pressure AND a blocked gas return bore. While not a symptom on most smaller lasers, this does happen on larger tubes. Gas is pumped rapidly around the tube, and small internal gas feeds have to exist. The feeds can get blocked, or on air cooleds, shorted out, by deposits forming inside the tube, from erosion or plasma etching.

Without running a really good check, I can only go from what the OP is presenting. If the PSU is good, with another head, it needs to be in the head, provided the heads match. If the head electronics are fine, its the tube.

Ignite, run, lase, plasma dies in 1-10 seconds, is a symptom of a gas or magnetic field problem in larger tubes.

This OP has a water cooled tube, with external magnet, and a air cooled power supply, if he has the compact PSU. I mentioned the fans because ILT used some interesting interlocks some times.

Steve

[dhg6]

One thing I forgot to mention there are three Jacks on the side. The first says interlock which I have a factory shunt that is made for it if you remove it doesn’t start at all. The second being a holder which is the wand and has a manual toggle switch, when this is thrown this makes it run for three seconds and shuts down. The third jack says foot switch and it has four male conductive pins in the same type of jack as the others. I don’t have this attachment. It dawned on me being a medical laser do you think it may be protocol to have to keep your foot on the switch to keep the laser active? In case a physician loses consciousness he or she won’t do as much damage to a patient. I’m only a junior member if granted permission I would happily upload some helpful photos I have taken. Again the Curtis meter bubble is parked real close at 250 hrs. The max is 10,000 hrs. Thanks in advance.


[QUOTE=mixedgas;219092]

But if the gas pressure is too low, it will either not start or have trouble starting, or run for a very short while and then 'sputter out', right?

If it runs for about 3 seconds and dies, and the supply is fine, it can have low gas pressure AND a blocked gas return bore. While not a symptom on most smaller lasers, this does happen on larger tubes. Gas is pumped rapidly around the tube, and small internal gas feeds have to exist. The feeds can get blocked, or on air cooleds, shorted out, by deposits forming inside the tube, from erosion or plasma etching.

Without running a really good check, I can only go from what the OP is presenting. If the PSU is good, with another head, it needs to be in the head, provided the heads match. If the head electronics are fine, its the tube.

Ignite, run, lase, plasma dies in 1-10 seconds, is a symptom of a gas or magnetic field problem in larger tubes.

This OP has a water cooled tube, with external magnet, and a air cooled power supply, if he has the compact PSU. I mentioned the fans because ILT used some interesting interlocks some times.

Steve

[mixedgas]

[QUOTE=dhg6;219265]One thing I forgot to mention there are three Jacks on the side. The first says interlock which I have a factory shunt that is made for it if you remove it doesn’t start at all. The second being a holder which is the wand and has a manual toggle switch, when this is thrown this makes it run for three seconds and shuts down. The third jack says foot switch and it has four male conductive pins in the same type of jack as the others. I don’t have this attachment. It dawned on me being a medical laser do you think it may be protocol to have to keep your foot on the switch to keep the laser active? In case a physician loses consciousness he or she won’t do as much damage to a patient. I’m only a junior member if granted permission I would happily upload some helpful photos I have taken. Again the Curtis meter bubble is parked real close at 250 hrs. The max is 10,000 hrs. Thanks in advance.


OH, its medical? NO freakin wonder. There is more then one model with this model number, and we were diagnosing the problem as if its a OEM laser. Sounds like your hitting the REQUIRED medical exposure safety board. Sir, I need pics to see what you have. Please disregard ALL of the above, until I get pics. Request will be sent to Spec for you to have pic upload, if you have not em... transgressed, I'm sure its possible.

Steve

[dhg6]

A picture is worth a thousand words so here is seven thousand worth. Thanks for all your help Steve!

Footswitch-jack.jpgHour-meter.jpgLightcard.jpgPower_supply-front.jpgPower-supply-back.jpgside-overall.jpgTopview.jpg

[dhg6]

Also this is not in medical or will be returning to medical use. Just for holography and possible light show use.

[mixedgas]

OK, water cooled ILT, rare beast.
Probably a dental curing test rig.
Now pop the hood on the PSU so I can play "Spot the Med Board ADD-ON!

Also need a shot of the board between the resonator rods next to the test (blu-grn-vio) bananna jacks

Thanks Spec (Brainnnns!)

Kind Regards,

Steve

[dhg6]

The third image in the above posting is the light card board if you look close(the one you requested with banana jacks). I will work on removing the powersupply cover and try to get some of those pictures but do you think the foot pedal switck has anything to do with this problem?

[dhg6]

Also this is not in medical or will be returning to medical use. Just for holography and possible light show use.

[mixedgas]

I need a board shot so I can see the components. I'm only seeing a "above" view, I need a side view.

Yep, footswitches are usually required. I'd say 75% of the systems I've seen or scrapped for tubes NEEDED the foot switch.

Almost every time, its two pins for interlock, two pins for the switch.
I cannot reccomend just adding jumpers till it works, usually the circuits are isolated and should not be cross wired.

What sets the delivered optical power? I'm missing something here.