Stoney's First Argon - ILT 5490A

[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!

[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.