Stoney's First Argon - ILT 5490A

[Stoney3K]

Today I went to Laserwinkel's to pick up the ILT argon head he was planning to sell me for about 6 months now.

Foto0430.jpg

The PSU and head as pulled from the Datronik casing. I did a test run and confirmed the whole lot was in working (and lasing) order before I took it home on the train. I must admit, there was something funny about turning heads when carrying a beige box which has a huge 'DANGER' sticker slapped onto it.

The head is in near pristine condition and the hour meter reads just over 500. During the test run, the laser power jacks read a voltage of about 0,121V (which, I guess, would be 121mW) and the current measured in at just under 8 amps. That is, until I discovered the Datronik had some switches on the back and could kick the whole lot into a 'high' setting. This was about 10,9A current (which, AFAIK, is maxing out the tube) and a power meter reading that was rapidly climbing to 300mV and beyond. I didn't run it on that setting for long because I wouldn't want to risk any runaway.

The ion got home safely but I haven't been able to run it in an isolated environment yet: Unfortunately the power supply (an ILT5400 switcher) was subject to some not-so-subtle aftermarket hacks which I need to repair first. More specifically, remove the 4 pin DIN jack that was used by the modified Datronik to control this unit in the first place, it has pins on it that read +, -, TTL and no connect, but I will need to take out the mod to find out what the original function was. Ultimately, I just want to put back a proper keyswitch and control the power with the little pot that's on the head (which is the intended mode of use).

Has anyone got some schematics or other useful information for the 5400 series? I've found plenty of useful data on the tube but hardly any info on the power supply. My first goal is to return this unit back to its original condition.

[mixedgas]

Has anyone got some schematics or other useful information for the 5400 series? I've found plenty of useful data on the tube but hardly any info on the power supply. My first goal is to return this unit back to its original condition.[/QUOTE]

In 20+ years of working with lasers, I have never seen a ILT schematic. Nor a JDSU schematic.

These are the guys who inherited ILTs IP, I have sent many people to them over the years, but they seem to be very shy, unless you have your checkbook out.

http://www.dzlaser.com/index.php?ID=75

Steve

[Stoney3K]

Never mind, I fixed it already.



The power supply has been modified to allow interlock and current regulation from some outside device (like an ILDA jack) without the need for the (probably quite expensive) original ILT remote controller. An extra circuit board with a relay and some analog magic was added and gives you two voltage inputs: One for laser power on/off, and one for current control. A few minutes with a soldering iron later, and I built the most elaborate power button I could imagine...



Just two lab power supplies, as I was too lazy to hack up a 6VDC wall wart adapter for the on/off voltage. Right-hand one controls current (which is at 0v, happily idling right now).

When it was built in the Datronik, somebody took a bit of artistic liberty and figured that 'idle' would be around these readings (Power on the left, tube current 10mV/A on the right):



Obviously, he wasn't doing his job.



Much better! I can dial the current down to under the lasing threshold if I wanted to, but I'm a bit reluctant to do so at the moment because I don't want to risk any tube damage.

A quick crank up to a tube current of 10A (Imax = 10,9A), which I don't intend to repeat ever so often:



If this meter is right, I just made a whopping 310mW of cyan out of this thing. Whoa! For an ILT 5490ACM, this is seriously over spec and I guess there will be plenty of photons left in this thing for me to enjoy. For normal runs on show-day, I'll stick to about 9 amps of current and 250mW of laser power, which should be more than enough for a lot of gigs.



Brightness comparison at 9A (250mW) with my 50mW DPSS green labbie which is outputting a little more than it advertised for. But it's never going to beat a pencil-thin blue beam.



Divergence test: Spot size of 10mm across on a piece of paper which was about 9 metres away. A divergence of about .99 mRad - that's an argon all right.

[mixedgas]

Your cavity optics are filthy, as evidenced from the transverse mode noise, but at those excellent power levels leave them alone.

ILTs are the toughest air cooled tubes, real works of art, lots of grain, and your results are typical of a low hours ILT. Set it up for 4 amps to 9 amps and be very happy. The cavity optics are dirty, but do not attempt to open them up at this current level of performance. ILTs are a bitch to realign, with inverted, sealed, optics mounts. Therefore leave the optics sealed and alone, but you can peak the fine adjusts which are near the optics mounts if installed(DO NOT TOUCH THE BIG COURSE Adjust screws) with tinsy tiny movements of a allen wrench.

ILTs optics train was intended to be sealed for a whole warranty life. No one intended that to be decades.

Can you put a grating on it? I'd like to know if it has a prism, all lines, or wavelength selective optics. If it has a prism, the rear fine vertical (if installed) selects wavelength. The fine trim is a flexure, not a MM style adjust, so tinsy tiny adjustments.

BTW< consider bolting it down to some aluminum, if the baseplate is getting warm.

It looks like the light pickoff beam splitter is filthy too. That you can clean.

Steve

[Stoney3K]

Your cavity optics are filthy, as evidenced from the transverse mode noise, but at those excellent power levels leave them alone.

ILTs are the toughest air cooled tubes, real works of art, lots of grain, and your results are typical of a low hours ILT. Set it up for 4 amps to 9 amps and be very happy. The cavity optics are dirty, but do not attempt to open them up at this current level of performance. ILTs are a bitch to realign, with inverted, sealed, optics mounts. Therefore leave the optics sealed and alone, but you can peak the fine adjusts which are near the optics mounts if installed(DO NOT TOUCH THE BIG COURSE Adjust screws) with tinsy tiny movements of a allen wrench.

I'm not going to bother with opening it up and cleaning or otherwise adjusting the optics. The thing is already running way over spec as it is now, so I would be foolish to try and 'tweak' everything for super power, complete TEM00 perfect beam. I'm planning to use it for my laser harp, so I'm more than happy with a little more powerful, multimode beam.

I set the idle current at 6 amps for now, I tried running it at 4 but it wouldn't remain stable, as I kept seeing the tube wash out and restart when it hit just under 4 amps. (I know it was not running under threshold as I heard the igniter every time)

Can you put a grating on it? I'd like to know if it has a prism, all lines, or wavelength selective optics. If it has a prism, the rear fine vertical (if installed) selects wavelength. The fine trim is a flexure, not a MM style adjust, so tinsy tiny adjustments.

Already way ahead of you.

lasert01.png

Lasing on 6 lines as it says on the tin!

BTW< consider bolting it down to some aluminum, if the baseplate is getting warm.

It looks like the light pickoff beam splitter is filthy too. That you can clean.

I can imagine it would be filthy, since it's been sitting in the old housing collecting dust with nobody bothering to put the cap on it for transport. Nothing a good bit of spit 'n' polish wouldn't fix, would a simple alcohol swab be good enough for the front of the pickup? I'm not sure if it has any special coating on it.

The rest of the unit is in need of a bit of a cleaning as well. The outer casing should be no problem, and I'm going to leave the heat sink alone for now since it would be too much of a hassle to open the lot up. The air coming out of the blow-hole at the top is warm, but not surprisingly hot.

The other thing to do is fix some cosmetics, like ordering the proper connector backshells and fixing that ugly hack on the PSU. I guess I'll take artistic liberty and cheat a bit, by putting back the key switch and adding a 3-pin XLR underneath which would be a 'remote interlock'. If I can find a good 6-12V DC supply inside the PSU I can leave it out altogether, but I need some DC juice to power the relay board that has been bodged inside of the unit. The added bonus would be that I have a proper modulation jack to control the tube current from the outside if I want. (The current control is too slow for blanking, so I wouldn't bother with that, but it's perfect as a dimmer.)

BTW, tube voltage is 104V at 9 amps on cold start and climbed to 106,6V after a 10 minute warmup. Filament voltage is 2,65VAC. (Right on the money, if you ask me.)

[mixedgas]

BTW, tube voltage is 104V at 9 amps on cold start and climbed to 106,6V after a 10 minute warmup. Filament voltage is 2,65VAC. (Right on the money, if you ask me.)[/QUOTE]

2.65Vac is Right on the money for a standard 5 turn cathode. You can pop the light sensor apart and clean the AR coated pickoff disk with a swab and alcohol. The solar cell leads are a bit small, so be careful. Note the direction that the disk is installed, some times it matters.

Perhaps one of the reasons ILT as a company failed early, besides some wild investments in laser driven dental whitening that was quickly surpassed by whitening that did not need blue light, was that they made too "good" a product and their tubes always exceeded spec and did not fail fast enough. Other ion companies made the money on the replacement tubes. The biology companies loved ILT for this. The tubes would last a long, long time.

Be careful, most ion PSUs have a high side and a isolated low side, and the high side will be at line potential.Both sides will have +/- 12 or +/- 15V sources. So you must choose your 12V source carefully. I'd call DZ and see if they would tell you where to get it off the PSU interface. Or use a external source.

6A is not worrisome, you have a bigger tube then you think. ~106V is about right for a 110VAC laser.

Enjoy it.

Steve

Steve

[absolom7691]

ILT heads bear a striking resemblence to the 60X heads (from the looks of it). Or is it the other way around?

[mixedgas]

Specific heads were developed for various end users. Other users copied the form/fit/function to compete for contracts.
Some times the only thing that changed was the baseplate mounting hole pattern.

60X is Xerox Photoprinter. (room sized high speed printer, prints a whole book in a minute or so)

60B is Hell Typesetter, which is where the side fans come from.

Omni532 is a 60X form factor clone.

NECs heads were SP161 clones for the most part.

I'm somewhat sure ALC predates ILT.

At one time there were at least 4 air cooled laser manufacturers in Salt Lake City, alone, all ALC or ALC spinoffs.

HGM and ALC were both owned by Laser Corporation, same tube designers, one line is medical, other production line was OEM/Scientific.

Steve

[absolom7691]

One of my first lasers was an ALC 60X. I loved it. It was a snap to service and realign. We broke down a ton of those at MWK. Took out the single-line, single-mode optics and put in some 60cm optics and got 180mW+ with 9 lines. I miss the old ion days. I also used to live about 5 miles away from Omnichrome in Chino, CA

[Stoney3K]

OK, it was about time the PSU got a little TLC and I un-hacked the modification done by Datronik.

Foto0434.jpg

There was a pretty straightforward mod in there which consisted of a relay (tripping the interlock circuit and replacing the key switch) and a simple wire which overrides the current control on the upper PCB. The wire pair which does the 'modulation' was connected to the terminal block next to the capacitor bank.

The fix was simple: Remove relay, and replace key switch in the proper circuit.

Foto0436.jpg

The end result, happily running at a set current. Instead of fidlling with PSU's, I can just plug the unit into the wall and turn the key for some coherent fun.

Right now I set the current for about 8,5A and a resulting power of 250mW. Should be more than enough for what I want to do with it.

Foto0435.jpg

The front of the PSU as it is now. It's still in need of some spit 'n' polish, as the key switch is slightly smaller than the DIN plug which was hacked into the housing and left a few holes where they should not be.

Furthermore, the head is missing a few screws and one of the PSU screws has been damaged. So there's still some cosmetic work to do here, but I need to order some components for that. (Also, end caps for the Amphenol jacks and back shells for the plugs)

Does anyone have information on which connector should mate with the original interlock jack? Right now it's populated with the factory supplied jumper.

I might put back the modulation wires and reroute them to a proper BNC jack, but I don't need it right now.

[Mel]

And readed this amazing thread looking for info about ILT heads and PS... Really great reading people at the avant-garde on this rare items!
Astonishing the work you do here and the knowledge shown by you all, too much to learn for me still! :-)

I received it yesterday from Germany, and still looking at it, reading as much as I can (not too much available! Less from builder's firms, or official schematics!), and praying for the moment *I dare* to connect it to line and stare at the blue-green photonic rain!
Not sure about how many AC watts it is going to drink from line. I know it's a 20A fuse, and know the specs thar appear at a pdf says exactly 20A for 220 AC (I'm in Europa), so gross figures could be 4.4KW, obviously a maximum -the 20A fuse would break over this level-. I'd like to know the minimum line powerage, as for maintaining it just over the 5-6A tube current... I assume half max. line power at this tube current level, say 2.2KW, but not sure if complete start-up procedure (carthode warming, starting kick, overall temperature stabilization...) will sum up a remarkable wattage to just tube comsumption. Well, again, poor official bibliography available, still googling for more, but according to what I've readed on the forums for the moment, I'm starting thinking it's not worth looking for *apocryphal* documentation.
Well, two fast questions, if you don't mind.

-Current control on the head: is it *clock-wise >> increasing power* or the opposite?
-Could I set this power control pot to the minimum -lets say full counter-clock-wise - and spect having no laser output; and then start slowly cranking it up and set it to approx. half-way and spect to be at half the power?

I obviously will plug the multimeters to read current, power out, and voltage, and also I will use a laser meter, but still I want to know what I can spect from the fiddling with the power control pot.

Well, thanks for reading, and thanks again for sharing your expertise and knowledge!

PS: I'm still going to browse for documentation, schematics, or whatever... I know it will be frustrating, but .."be water my friend!", perhaps I step over something (I'm now really optimistic! XP). Moreover, it would be great to find a controller, the RPC-50 remote controller that the "barely readable" pdf I've found talks about. Well, and later I will try to round the square, start an antrigravity experiment with a pair of spoons, or something a bit more possible than finding this f***ng documentation! XD

Cheers!

[Stoney3K]

Great to see another ILT user on this thread. Don't hesitate to post any pictures!

I've done a run-up on mine and can answer your questions without much trouble:

The power control pot on the head (assuming you have a 5490ACM head with 5400 PSU) is clockwise to increase power. Depending on your tube, it can set the current from 4.5A up to 11A, which is the maximum current the PSU can supply and is not recommended to run for too long. When on the bottom stop, the tube may wash out and lose its laser output, but if the current drops, the PSU will automatically try to restart.

When running, the unit will draw up to 10A from your 230V grid. However, I have yet to reach that current even with the tube pushing Imax, so don't expect your breakers to pop by running the system. 120V @ 11A is the maximum that will run through the tube, giving about 1200-1500W for the tube only and about 2000W for everything including the losses in the PSU and fans. There's a sticker on the back of the PSU with a serial number and current rating. (The fuse is only a safety measure)

I have yet to find any documentation for the remote control interface, but I managed to figure out the interlock circuit. If you have a German system, chances are it was pulled out of a laser display system and it has a 4-pin DIN jack on the power supply. If you have the mating plug, you can use that directly, if not, you can replace the relay board inside the PSU with a simple switch or a key. Bear in mind, the interlock circuit itself is connected to the line directly via a split tap at the EMI filter. Make sure you get a switch that can handle 250VAC at low current. Be careful, since I am not sure whether the interlock loop is insulated from earth or not. (I need to pull the entire PSU apart to find that out.)

Be careful when connecting your multimeters, especially the one for tube voltage (connected between 'CATHODE VOLTAGE' and 'ANODE CURRENT'). I have no idea whether the jacks are somehow insulated from the starter circuit and you may risk losing a meter because of the start zap.

[Mel]

Hey, that was fast answer Stoney3K! Thank you very much!
Yes, I can see I'll have to be carefull... Specially I won't measure tube voltage, to avoid starting-zap hazards...
Would you connect the meters AFTER starting the thing, or only this could be valid for the tube voltage for zap avoidance, as said?

I guess it is wise trying to start the tube at lowest power, setting the head-pot totally CCW; the manual says that to start it easily one should set it to full power!
I think best is starting with low power and, if it doesn't ignite, crank it up till it lases. Do you agree?

I've been lucky and could find a pdf manual, which I gladly post here. I'm not sure if it is legal, but provided the absolute absence of info online, neither I'm sure who could blaim against posting it here! Cards-up speaking, the seller kindly sent it to me when he/she found it and I asked him/her a similar bunch of questions, as the first post I've posted here. I'm totally gratefull to the seller, as there is a kind and fluent communication and it is a totally helping person (you know, when one dares to have a deal on the net... everything is possible!). Anyway, he/she assured me it is play&plug, along with some enlightments about safety, which I specially appreciated.
So I hope it is helpfull for anyone in the future. For me, it answered the main questions I was wondering about... Specially important though, are your experienced comments-readings on working units. That's awesome! I will post my first readings when done...

Having said that, I think I will dare to start the baby this evening. I'll take pictures of the beam (if successful!), and will try to post pictures of the head and ps themselves.
Thanks for your help Stoney3K, I bet I will go back soon asking something more... :-)

Cheers!

PS: The 5Mb upload limitation made me impossible to upload a single pdf file (it was 5.6 Mb, a bit MORE compressed!). So I'm uploading png graphic versions for each page (22 pages). Sorry for that!

[Stoney3K]

Hey, that was fast answer Stoney3K! Thank you very much!
Yes, I can see I'll have to be carefull... Specially I won't measure tube voltage, to avoid starting-zap hazards...
Would you connect the meters AFTER starting the thing, or only this could be valid for the tube voltage for zap avoidance, as said?

I guess it is wise trying to start the tube at lowest power, setting the head-pot totally CCW; the manual says that to start it easily one should set it to full power!
I think best is starting with low power and, if it doesn't ignite, crank it up till it lases. Do you agree?

If the tube is working properly, it should start lasing even at low current (completely CCW) at a power of a few mW. (Mine runs at 20mW when idle, and can run all the way up to 310+ mW when at 11A, but keep in mind, my tube is in near-new condition). If you have any doubts, turn the pot completely CCW and then go clockwise for about a quarter turn. If the tube does not lase then, it may be on high pressure or damaged.

Starting with the current at full blast (pot completely CW) is possible but not really recommended as the plasma tube will get one hell of a thermal shock, especially when starting from cold. Sure it will work, but it may shorten your tube life.

The reason it is recommended in the manual for INITIAL startup (for a brand new delivered system) is to ensure the laser can perform at rated power and to make sure all components can settle thermally. Also, running 'er for a short while at full steam means the getters in the tube can get to work and all of the useless gas in the tube is buried -- leaving more argon for the laser to work with.

Once the head is running, plug in the multimeters. Don't try to plug them in any earlier (after all, you're not gonna need 'em during start) just to be safe instead of sorry. Also, there's no reason to measure all of the values simultaneously -- you can do all of them one at a time and change the current set-point after that.

If she's a proper runner, set the tube up for a current of about 8-10A depending on how much laser power you need. Tube voltage at 10A is a good indication of gas pressure and remaining tube life, while cathode heater voltage is an indication of possible cathode wear.

[Mel]

Hello!
Just to roud my previous post, I'll post here some pictures about my first test of my ILT.
Thanks Stoney3K for inviting me posting pictures on this thread.

=====REPORT=====
Aprox. ambient temperature: 23 Celsius (75F aprox.)
Time on: aprox. 40 min
First start, at lowest power using the head pot totally CCW.
It started at first attempts, but seemed to want more power, as it was flashing from two "power modes". No beam stop between flashes, beam continuously flashing each 1sec. or so, from low intensity to twice (at sight) the power. Beam was stabilized by increasing power turning head's potentiometer CW. The setting, when the beam was stable, had this measured values, taken with a multimeter on the head's plugs:

Laser Power: 0.73 V (dropped to 0.71V past 4 or 5 minutes)
Cathode Voltage: 2.71 VAC
Anode Current: 72.5 mV
Tube Voltage: 101.6 V

If I'm not wrong, that should mean: 70 mW of output power at 7A tube current, isn't it?

Several minutes later (15-20 min) I turned up the power a bit more, and measurements were:

LP: 1.044 V
CV: 2.71 VAC
AC: 81 mV
TV: 102.4 V

Again, If it's right, that means 100 mW at 8A tube current, right?
I didn't go up with the power, as I was worried with the "ghost beam" that shows at the pictures.
I readed that this could be from brewsters reflections or coatings peeling or not in 100% wealthy state... Should I worry? It is not so strong anyway...
When I have a more accurate way of measuring it, I'll find out its power. I also have to test it at 9-10A, but for now I had to "locate" the set in my house, making it "wife-compliant"

I tried to measure with my laser power meter (IL1400A with SPL024 sensor), but I found no sense readings and assumed it is not specially good for 488 and blues in general (it gave a power of 15-19 mW on first-second measure). Have to take it to re-calibration.

So now, and finally, the pictures. The spectrum was done using a CD. Thanks for reading/comment!
IMG_1994.JPGIMG_1993.JPGIMG_1997.JPGIMG_1986.JPGIMG_1987.JPGIMG_2000.JPG

[Stoney3K]

Your ILT seems to be in good shape, for one thing, the power supply looks brand new (not even a scratch!). Even for historic purposes, I wouldn't touch this thing with any tool -- right now, it looks like a museum piece which just dropped out of the factory's marketing folder.

Tube seems to be OK, 100mW @ 8A with 102V tube current is nothing you should worry about. Gas fill pressure is probably slightly lower than on mine (compare tube voltages), but that's probably by design instead of a problem. These tubes were *designed* to make 150mW @ Imax, not over 300.

The ghost beam is probably the result of some dirt inside the cavity. I wouldn't worry about it too much since the system is in working order, and tweaking/cleaning the cavity optics can kick everything out of alignment or damage the tube or optics if you don't know what you're doing.

Run her for a few hours at 8 amps, that could bury some of the gunk in the tube and keep an eye on the laser power. If the tube gets more pure argon, power will climb. Remember, this thing was probably on a shelf somewhere for a few years, and it has little time on it, so running it once in a while won't hurt the laser.

[Mel]

I'm absolutely happy with your conclussions! yeah, it seems I've taken a good deal. According to the seller, the tube has low hours (approx. 40 hours they assured), it seems so by the "Curtis", but still I wasn't convinced, as I readed that Curtis meters are "hackeable". What I have to get now is a proper light-meter to have some direct-beam measurements. Also I have to make the several-hours run you suggest, but I'm going to wait till I have a meter with known callibration. It would be great to data-record the values during several hours, and take out some graphs...
Well, Stoney3K, If you don't mind, I'll post the results here when done, if this doesn't bore you! I could also start a new thread, please, let me know. I think our ILT's are so alone that perhaps talking about them here will make them happier

Well, thanks again Stoney3K.

[Stoney3K]

OK, I had to perform some maintenance on the power supply since one of the components decided to call it quits.

Here's what happened:

Last time I ran the system it was irresponsive to breaking the interlock through the keyswitch. Which left the laser pretty much in a state where it is unable to shutdown nicely, as pulling the plug on the PSU also means the fans are cut off and the tube has no chance of cooling down. Causing thermal stresses, misalignment and other nasty stuff.

I ultimately performed an 'emergency stop-gap' shutdown by dialing the power all the way down on the head, keeping the system running like that for about 30 minutes and allowing the tube to cool down as much as I could, before disconnecting power. For obvious reasons I was not going to run the head any longer unless I could get the PSU repaired.

What caused the problem was the solid state relay that supplies power to the main transistor banks and the cathode transformer was (for some reason) in a stuck-on condition, so the relay kept conducting no matter what. So that was a good excuse to pull the entire PSU apart, clean it out and put it back together again, replacing the semiconductor relay with something more archaic but reliable: A simple SPST switch.

PSU is squeaky clean now, I will add a write-up with photos later. The fan is also a lot less noisy now that it doesn't need to move all of the dirt around

[mixedgas]

Ghost beams are normal. They have NOTHING to do with peeling optics or other failures, its the second surface of the output coupler making a Fresnel reflection. Most lasers have a AR coating on the output side of the mirror to reduce the ghost, but it is merely a minor consequence of the laws of physics, you can reduce them at the design stage, but they always will be there.

BTW, if a optic peels on you, the whole optic will usually be gone in a period of minutes or at most a few weeks.

Steve

[Stoney3K]

Ghost beams are normal. They have NOTHING to do with peeling optics or other failures, its the second surface of the output coupler making a Fresnel reflection.

Mine has a slight ghost beam a well but is working without any problems. I figured it was normal and didn't worry about it from the start.

Given the high output power, could it be that the tube in my head was replaced with a tube from a 5500? Those were rated to run at 300mW and a splash more current (11A).

When I have the time, I may go over the head's internals as well with a toothbrush to clean out all of the grit. The PSU was fairly smudged up and looks a lot better now. Too bad about the interlock relay though -- buying a new one of those off the shelf would set me back almost as much as I paid for the laser, so I'm not going to do that. If I can find a mechanical relay that can do the same (with proper current rating), I'm all for it.

[Stoney3K]

Small update since I figured the head could use a bit of TLC, also giving me plenty of chance to make a few internal shots.

DSC_0546.JPG

View of the head's guts with the cover removed. I was surprised by the lack of dirt inside the laser head, given the amount of air flow going through it at run time. A few nooks and crannies had some dust collected on them, but nothing serious, and the only major cleaning I had to do was clean the fan blades and remove some grease residue from the cover. Nothing a damp cloth couldn't fix.

DSC_0554.JPG

Shot of the anode end of the head. The OC is just out of frame on the lower left half of the picture. Also note the teflon blocks covering the Brewster stems, and a set of lines going to a pair of can-shaped objects between the fans (one leading to the cathode, one to the anode end): Could these be gas refill ampoules? In that case, I'm very happy, since both of them seem to be untouched.

The tube serial number is #49622-1 with an argon fill.

DSC_0549.JPG

Shot of the light control and starter card. Compared to the medical board in a water cooled 5500WL, this could hardly be called a circuit board.

DSC_0559.JPG

And a beauty shot on how this machine should look like! Given this thing is a quarter of a century old, I am still surprised by the toughness of it. There are still a few minor bits and bobs to fix on the head, for example, the resonator cover on the OC end is still missing a few screws, which weren't present when I bought the unit.

Unfortunately, every war has its casualties, though:

DSC_0560.JPG

This is what's left of the beam splitter supplying the light sensor with a pickoff beam. No serious harm done, but it was cracked when I was slightly too careless to replace the aperture cover and tightening the screws.

The only obvious result is that the light sensor is now non functional: Not that I really need it, however, it means I need a small modification to the PSU to make it run in current regulation mode. Right now it will just give the head everything it's got, which is 12 amps at 110 volts. Sure, it makes for an impressive display of laser power, but the tube doesn't like it for very long. On the brighter side (literally!), it also means the beam isn't obstructed by another piece of glass anymore and the full 300mW of coherent photons is at my disposal.

Since the PSU still needs a bit of work anyway, it's not a major disaster. If I can find a replacement piece of glass that will fit, I may repair the light sensor and restore the whole head to its former '87 glory, but right now, I'm glad it works. I've reconfigured the PSU to run in 'standby' mode (idle current) and adjusted it for a permanent 6,7A on the tube. Once I can find or build a proper remote I can always go for current control instead.

Mixedgas: Which pins on the remote connector do I need to control the tube current?

The PSU still needs a bit of a cosmetic rework and some adjustments, including replacement of the main (solid state) relay that supplies the laser with power, but I need some components for that. If anyone has a dead PSU which contains a similar relay capable of switching 240VAC / 20A, just let me know.

[DancingMolecules]

Hi everyone,
Thanks for your great help and interest in this tank of a laser.

I recently acquired this laser in a non-working condition. The first issue was the radiator was dirty and the thermal grease had dried up. I took apart the radiator, cleaned it, put on new thermal grease to get it stable and working. After tweaking for a while I got it working great. My model has a Littrow prism in the back that allows tuning between 514 and 488nm with a SLIGHT turn of the mirror gimbal screws.

One day, when going back and forth between the wavelengths for my experiments, LASING disappeared. After careful adjustments back to the original mirror positions, there was no lasing. Then I did what you are NEVER supposed to do and I adjusted all the mirrors and probably F'ed this thing up completely.

I have checked all the electrical outputs and everything seems to be the values you guys have and the power source seems to be working fine. I am assuming I have completely mis-aligned the cavity. I checked a few places, and someone suggested shooting a HeNe laser down the cavity to monitor the reflections, but I can not see the important reflections and any adjustments of the mirrors dont seem to do anything to the HeNe beams that I can see.

QUESTION::Can misalignment damage the tube in anyway by current spikes or????????

So, anyone have some information or the patience to help me out??? This was a fantastic laser when it worked.

Also, I have a digital copy of the manual for the ILT 5400 series that I got from a tech company. I am new to this forum, so if you tell me how to upload it, I will do so with pleasure. However, it sounds like you all know more than what the manual tells!!!

Enjoy.

[DancingMolecules]

Enjoy. THEY REQUIRE AT LEAST 15 CHARACTERS PER MESSAGE

[Mel]

Really annoying I guess... If you was fiddling with the wavelength when it suddenly refused lasing it would make sense that the littrow prism had lost its correct position... also a sudden gas-out I guess, but perhaps you don't want to think about that reason!

Hi everyone,
Thanks for your great help and interest in this tank of a laser.

I recently acquired this laser in a non-working condition. The first issue was the radiator was dirty and the thermal grease had dried up. I took apart the radiator, cleaned it, put on new thermal grease to get it stable and working. After tweaking for a while I got it working great. My model has a Littrow prism in the back that allows tuning between 514 and 488nm with a SLIGHT turn of the mirror gimbal screws.

One day, when going back and forth between the wavelengths for my experiments, LASING disappeared. After careful adjustments back to the original mirror positions, there was no lasing. Then I did what you are NEVER supposed to do and I adjusted all the mirrors and probably F'ed this thing up completely.

I have checked all the electrical outputs and everything seems to be the values you guys have and the power source seems to be working fine. I am assuming I have completely mis-aligned the cavity. I checked a few places, and someone suggested shooting a HeNe laser down the cavity to monitor the reflections, but I can not see the important reflections and any adjustments of the mirrors dont seem to do anything to the HeNe beams that I can see.

QUESTION::Can misalignment damage the tube in anyway by current spikes or????????

So, anyone have some information or the patience to help me out??? This was a fantastic laser when it worked.

Also, I have a digital copy of the manual for the ILT 5400 series that I got from a tech company. I am new to this forum, so if you tell me how to upload it, I will do so with pleasure. However, it sounds like you all know more than what the manual tells!!!

Enjoy.

[Stoney3K]

Really annoying I guess... If you was fiddling with the wavelength when it suddenly refused lasing it would make sense that the littrow prism had lost its correct position... also a sudden gas-out I guess, but perhaps you don't want to think about that reason!

I agree: The cavity is probably misaligned and it is possible to re-align it. Also check Sam's Laser FAQ for a good starting point on realigning a gas laser from scratch.

Misalignment won't damage the laser tube, unless you abuse the mirror gimbals to an extent that the Brewster stems snap off. You're going to need one hell of a lot of force to do that, though. If the tube is up to air, the PSU would never be able to start it.

If the PSU has no problems and the plasma tube runs as it should (about 103V at 8A, depending on the amount of gas) then the problem is optical and you can look at re-aligning the cavity. I don't know if there are any specific procedures on realigning the HR when there's a Littrow prism present -- you may need to consult Steve (mixedgas) on that matter as he's the local neighbourhood ion guru.