ILT 5500A Questions and Help

**Stoney3K** · 01-09-2012, 15:58

Originally Posted by mixedgas

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** · 01-09-2012, 16:35

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

**Stoney3K** · 01-09-2012, 22:20

Originally Posted by dhg6

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** · 01-10-2012, 06:21

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** · 01-10-2012, 08:56

Originally Posted by 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.

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** · 01-10-2012, 16:43

Originally Posted by mixedgas

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** · 01-11-2012, 02:37

[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** · 01-13-2012, 06:51

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]

Originally Posted by Stoney3K

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** · 01-13-2012, 10:23

[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