ILT 5500A Questions and Help

[Stoney3K]

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.

[mixedgas]

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

[dhg6]

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.

[dhg6]

My thoght solder a small jumper from the h to the f what do you think?

[Stoney3K]

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.

[mixedgas]

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

[Stoney3K]

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.

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.

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 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.

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.

[dhg6]

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.

[Stoney3K]

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.

Wait for Steve (Mixedgas) to reply in here. He may have some pinouts that can help you set this thing up properly.

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.

[dhg6]

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.