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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 :eek:
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.
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
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.
"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!!
[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
Thanks for the answer. Tungsten has some interesting properties huh.
yeah, but only half the number of phase states of plutionium. :-(Quote:
Originally Posted by onelightmind
Steve
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.Quote:
Originally Posted by dhg6
Steve
That would be the case, were it not the 5500 supply is a switch-mode.Quote:
Originally Posted by mixedgas
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.
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?Quote:
Originally Posted by dhg6
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?
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.Quote:
Originally Posted by dhg6
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?Quote:
Originally Posted by mixedgas
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.
[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
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]Quote:
Originally Posted by Stoney3K
[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
A picture is worth a thousand words so here is seven thousand worth. Thanks for all your help Steve! :)
Attachment 29784Attachment 29785Attachment 29786Attachment 29787Attachment 29788Attachment 29789Attachment 29790
Also this is not in medical or will be returning to medical use. Just for holography and possible light show use. :)
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
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?
Also this is not in medical or will be returning to medical use. Just for holography and possible light show use. :)
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.
Light feedback or there is a twenty turn pot on the card side of the unit you can take it from 1.5W down to about 200 mw was the lowest. I never found the med board here is an overall photo of the power supply. I will work on a sideview of the light card you requested. :)
Attachment 29792
At least its a standard PSU, or sure looks like one.
Would like to see a bit more heatsinking though.
Not saying its under, but I like heavy metal for CW.
Steve
Light feedback or there is a twenty turn pot on the light you can manually adjust from 1.5W down to about 200mw. I couldn't find the med board specifically but here is an overall shot until I get the cover off to get that sideview of the light card.Attachment 29793
I took a picture of the twenty turn pot, the cover where you acess and the junction connector on the board. fs stans for foot switch H stands for hand piece. :)Attachment 29794Attachment 29795Attachment 29796
Sorry for so many replies here is an overall of the side of tha board but the part I think you wanted was the last picture above of the operator interface. This is directly plugged on the back side going to the three input switches we where talking about.
Attachment 29797Attachment 29798
The PSU is stock, in fact, I envy you for having an ILT head and PSU that are in such amazing condition!
Especially given the fact that you have the water cooled 1,5W version on single phase, this one is beyond unique. Not even a scratch on the casings, circuit boards look brand new without a speck of dust. I'd hold on to this puppy if I were you -- you're looking at a priceless collector's piece.
It's almost a shame to sabotage the medical circuitry on the head to allow it to operate CW since it would compromise its original condition. Steve: Is there a way the board can be disconnected with some degree of elegance so the (internal and external) cosmetic condition of this beauty won't be violated? ;)
If I were to play on a hunch, I would defeat the entire operator interface on the PSU connection end. The PSU itself doesn't know about the fact that there's a medical laser on the other end, it just notices the interlock is broken after a few seconds of run-time, caused by the operator interface board. So defeating that (and only leaving the case interlock intact) would make it run CW.
You'd have to be careful and sure if the PSU can supply enough current to the laser all of the time though. 1,5W is a lot of power and you'd need quite a lot of juice to keep that up.
He'll have to derate it for CW use, the power supply that is.
Basing things on the Omni 643 to Lexel 75 or 85 size tube, and assuming a 220 PSU, try around 400-500 mW MAXIMUM CW for a while. Guessing that is around the upper limit of the PSU for long term. One likes to run one's lasers less then the max. If its a 110 PSU, we need to revise the estimate.
The board that says "operatory" on it is the medical board.
Assuming no mods to the PSU, and if you can keep the light feedback or get it into current mode, all you'll need is a FLOWSWITCH for the coolent and a remote for the PSU. The remote is not hard to build. Getting the pinout may take some time.
I'm willing to bet they did not hack the PSU other then boost the current limit and use a beefier FET array. That does not help you much for CW as the heatsink is not massive. I'm betting they beefed up the supply control rail to power the solenoid, or something, they need a bit more power in the head then usual, so I'd check for extra pins on the PSU head connector that may "Bite" or have AC on them.
I'd like to see a pic of the PSU heatsinks before I comment further.
YMMV, its a prototype or demo unit. Its missing much of the precautionary circuitry usually found on a medical laser, usually there are many, many, safety boards.
At this point in time you need either a good technician, some patience, or a friend who is a Electrical Engineer who does analog.
Steve
This unit is made to run continuous duty I assure you that. This is a 220v @ 20 amps. After looking at the inside of the footswitch input the center middle pin isn't connected only three wires are. Do you have an idea from this picture what two points need to be jumpered to close the footswitch I'm willing to try it. At worst it will more than likely shut down as it has when I've disconnected the flow swith and thermal. :)
Attachment 29799Attachment 29800
My thoght solder a small jumper from the h to the f what do you think?
Attachment 29801
I would at least try to measure the voltage between the H, FS and + terminals before jumpering wires together. Try to find where the pins on the Footswitch connector actually lead to. I'm not going to guarantee anything, but my guess is that the pins mean case interlock (SH, Shield or Shell), foot switch, hand piece and interlock.
There's a good chance the foot switch controls the laser power in 2 settings, so jumpering 1 set of these wires would be low power (low dosage) and the other would blast it at the full 1,5W.
The easiest way to run it CW is to bypass both the medical board and the light feedback card altogether and just use the current control that's on the head, which should connect to one of the pins on the umbillical. I don't have the pinout for that here right now -- maybe Steve can point you in the right direction for it.
Again, the PSU is completely clueless about the fact that there's a medical laser on the other end: As long as it can see there's a working laser connected, it will happily flow current. If the laser doesn't support light control (or if it was deliberately sabotaged, heh, heh), it will supply current up to a certain set point which can also be controlled with the little potmeter you discovered earlier.
@Steve/mixedgas: Don't let the PSU compactness and lack of heat sink fool you. This thing is a full SMPS, not your old friendly neighbourhood "they don't build things like they used to" passbank. For example, the whole laser is connected directly to the rectified line via a plain buck converter. I've pulled mine apart completely already, and the main transistors are at the bottom board of the PSU. They have quite the heatsinks.
I own one of the 220 ILTs too. I've just seen a few people burned by some med grade switchers out there that are pulsed duty (many HGM models) that have a tiny, tiny, heatsink. My best friend services the HGMs, and I love the one that delivers 35 amps from a heatsink module that is the size of a pack of cards. The filter cap is the biggest thing in the PSU, and the cathode is heated by a switching psu. However, it only does it for 30 seconds.
I guess I'll have to reverse engineer my remote. Its the nice one with the 50 LEDs for current and light.
It will take a few days, I have some other projects to do.
Stoney, I've been servicing these things for 20 years now, including the switchers, I'm just trying to err on the side of caution.
I've seen some shortcuts taken. So I'm VERY cautious when I give advice and I dont have my hands on the unit.
ILT air cooled manual, sans pinouts:
http://class.phys.psu.edu/p457/manuals/ionlaserman.pdf
I'll find the generic ILT pinouts if I can.
Steve
Even the cathode was heated by a switching PSU on those units? Now that's pretty impressive... as far as I've reverse engineered my own PSU, the cathode is being heated by a good ol' transformer off the AC line. Frankly, for the cathode filament, I really wouldn't want it any other way.Quote:
Originally Posted by mixedgas
I can understand. Especially on a switcher which is connected straight to line, it's really dangerous to get bitten if you don't know what you're doing. There are no components to limit the current going from the grid, through any 'illicit component' (and that includes an inadvertent operator) in the chain.Quote:
I guess I'll have to reverse engineer my remote. Its the nice one with the 50 LEDs for current and light.
It will take a few days, I have some other projects to do.
Stoney, I've been servicing these things for 20 years now, including the switchers, I'm just trying to err on the side of caution.
I've seen some shortcuts taken. So I'm VERY cautious when I give advice and I dont have my hands on the unit.
I've worked on a 2,2kW class D audio amp once which had a very impressive cascade failure once I switched it on and fixed what I thought was the problem.
An update. I did some probing how the other switches are wired. I made a jumper that goes across the two top pins. Now when you throw the switch the alarm chirps that laser is on, the yello treat light comes on and the grean beam led flashes but runs and still shuts down. Looked closer and checked how to bypass. Made a jumper from the right top pin to the bottom ground pinBOn the seventh day god said let their be light It stays on. Downside my little fans stop and no leds so I still have a problem that the board is calling for shut down. By the way I am an electronics engineer at first data resources just had my poker face on and haven't troubleshot lasers this deep with no schematics. Any Ideas after my new findings the tube is more than healthy and schematics or Ideas would be greatly aprreciated. Or throw it around in the laser network and see if anyone you are friends with may know something else. I love this website I'm an old laser tube junkie I love the new semicondutor lasers for efficiency but my heart is in tube lasers. :)Attachment 29859
Wait for Steve (Mixedgas) to reply in here. He may have some pinouts that can help you set this thing up properly.Quote:
Originally Posted by dhg6
Jumpering random pins because you think they know where they go (and what the buttons they control are supposed to do), and then blissfully expecting it to work, is not the way to get this thing running. Worst case, it could fry your tube or power supply in the process.
It may help a lot if you'd share your reverse engineering results with us so we can review them.
Ok sounds good. I just wanted to let you know the tube is very healthy. I will document each pin to where it goes respectfully and reply after I have it comepleted. Thanks so much for all the help both you and Steve have given me. I would sure like to make this work with full board functionality and run correctly. :)
Just a little update of the tube output. I could only get it down to 500mw and it's still bright as the sun. My camera was in fireworks mode as it was to bright in any other setting. I shot it into some diffraction grating but didn't have a tripod so it's a little blurry but very stron green and blue lines. :) Now we can work on getting the board working correctly instead of bypassing operatory inputs. :)
Attachment 29866Attachment 29867Attachment 29868
Looks great! So you have no trouble to run the tube in CW for longer periods of time anymore?Quote:
Originally Posted by dhg6
Can you post some measurements on the tube (e.g. cathode AC voltage, tube DC voltage, tube current) at different power levels so we can get a general idea on its condition?
Yes I built a recirculation unit with an ice bath. The thermal cutouts still work because until I put my ice bottle in, it got hot and shut down so the board isn't completely bypassed. After I put my ice bottle in no more shut downs and the water on the exit line comes out warm but not hot like it did before I put my larger volume pump in and Ice. I will build a real chiller when I get the unit repaired correctly but it has no problem running continuous duty. Can you measure the tube without frying a digital multimeter? As long as you use the banana Jacks on the side panel? I don't want to fry my meter.. The jacks are laser power (blue jacks), cathode voltage (green jacks), and Anode current (violet jacks). :)Attachment 29869
You can use the jacks without any risk to your meter (see the manual).Quote:
Originally Posted by dhg6
The tube voltage can be read from the leftmost anode current jack together with the leftmost cathode voltage jack, and it reads DCV directly. Make sure you use the proper range (around 250V).
Take care to connect the meters only after start, since I'm not 100% sure if they're HF decoupled, so some high voltage from the starter may bleed through.
You know a tube like this normally gets a minimum of 2 gallons per minute through a garden hose, right?
You need to get rid of up to 7 Kilowatts, and if the thermals are tripping, your very short of coolant.
Ice baths dont last for long, and the huge thermal gradients are hard on the tube.
Also watch your anode temperature, that fan cooled anode is a weak spot.
Steve
Agreed. If you only run it for short periods, just hook up a garden hose from the wall and dump the waste water down the drain. It won't ever run out of cold water and you're not going to have any problem with cooling like that. I cooled a SP168 from the wall and the water on the drain line was only hand warm, so you'll have plenty of cooling headroom. Not recommended for long runs, unless you have a deep pocket and don't care about your water bill ;)Quote:
Originally Posted by mixedgas
7kW might be a bit optimistic though, since the 5400 series PSU's have a 20A fast blow fuse on 230V single phase, so you'll only be able to pull 4,6kW from the grid.
Ok the tube voltage when I first started was at 207.8 vdc. after warm-up it stabilized at 148vdc. respectively. Cathode voltage was at 3.1vac (seems resonable). I don’t know if the 5500 manual is the same as it is for this unit. It dictates 10 millivots=1 amp for dc for anode current. I measured 9.5 millivolts that would make it drawing less than an amp. That can’t be right.
This unit has 1/4 " tubing and I'm on a well so I don't even want to run well water through it. I do have two type of filters installed in my home, one to remove minerals and the other is a no salt softener. I am currently using a 10 gallon recirculator with distilled water. My ice bath works perfect and it's using a custom fitted 1/4 hp 1500gph pump It has better flow than any home tap. It's restricted not to push more tha 40 psi. water is warm to the touch on the return line. I am going to build a chiller coil when I fix this thing correctly. :)
That sounds like too much of a drop. 207.8V is good, but 148VDC is just not right for a 5500 tube.Quote:
Originally Posted by dhg6
It sounds like your power supply can't deliver enough juice to keep up the amount of current this thing needs (it would also explain the low current reading). What are the readings with the power control on minimum setting?
took readings again. tube is definately at 148vdc. power is at 8.3vdc book says 1 milliwatt=.05vdc I'm at 1.6 watts of power. the anode current measured 132mv. my meter must have flipped out the first time iI took it. it's at a 132mv = 13.2 amps according to the book. Is their a pot on the light card or board of the head that lets you adjust tube voltage. here is a b picture of three pots and a side view.Attachment 29878Attachment 29879