Uniphase 2214-25ML fireworks

[CountFunkula]

Hello! This being my first post, let me say that I thoroughly enjoy this forum...best place on the net for all things LASER!

I just came into some JDSU gear. 2114-40MLA PSU with 2214-30SL and 2214-25ML heads. Spent all day testing the heads and they performed exactly as expected. The previous owner of these lasers informed me that the multiline head was nearing the end of its life and a few of the lines were not showing up. I fired up the multiline to ~10A and got 7 lines. My remote informed me that the tube was outputting close to 70mw... WAY over the head's 25mw rating. Then something bad happened: the beam clicked off and sparks started coming out of the air holes near the front of the tube....and yes there was a fan connected. I took a cursory peek at what I could and noticed a melted wire or two...I didn't spent too long trying to diagnose the problem because the meltdown made me very sad.

Anybody have any ideas what happened? I really hope whatever happened is repairable...that multiline was way cool. Im going to take a better look at it tomorrow [once I figure out how to get the enclosure off ] and will post some pics.

I sure am glad that multiline head was free.

[GooeyGus]

The previous owner of those heads is right here


I'm guessing some of the heat shielding on the anode wire must have failed... that is the only thing toward the front of the head with any sort of real power going to it. It should be pretty easy to fix! Worst cast scenario would be having to take the tube out of the housing, which isn't too big of a deal.

I never took that multiline above around 8.5A. I had a feeling those green lines might show up at 10A, but since I hadn't ever taken it that high (due to the controller I was using) I couldn't advertise that they were there.

Glad everything is workin' well, except the minor explosion... haha.

Like I said to you in an e-mail I sent last night, I ran that thing for about 20 hours at 8.5A hoping that it may bring the tube back to life a bit, with no luck. BUT you would think that it would have failed during that long run if there was something wrong with it. I've never seen sparks come out!!!

[Diachi]

As Jason here says, it sounds like the anode lead has failed in some way, it may have come loose and shorted onto the case , which would cause the sparks and melted wires. That or the wires melted first, then having no insulation shorted to the case and caused the sparks. I reckon it's something along those lines though.

I was going to comment on removing the tube on that head ... but I have no experience with that model, I've only ever worked on the square 2211-XXXX heads so I know next to nothing about the round heads.

Good luck getting it fixed, hopefully it's nothing serious.

Regards,

Adam

[GooeyGus]

I was thinking it shorted on the case at first, too, but then I remembered most of the case is a composite material... fiberglass or something similar.

There are a couple ground wires leading up next to the anode wire, which could have caused a problem. Either way, it really shouldn't be a big deal to fix at all. I've taken these tubular heads apart a billion times, so if you need any help just let me know

[CountFunkula]

All right! What's up Jason? Definitely glad to see you on here.

What kind of remote were you using on the multiline? I had no problem taking it up to 10A with a JDSU 2500. I do recall 7 lines showing up at around 8A, so whatever you did, the universe was definitely cool with it. I definitely agree that it's probably an anode connection as the sparks REALLY flew [from the front of the tube] when the igniter fired. Again, I'll post some pics once I get the workbench cleaned off and the head opened up.

[GooeyGus]

I was also using a JDSU2500, but mine is a bit of a gimp. It only allows the tube to idle, or to be turned up to a certain current level until it sees the light output it likes, then wont go higher. It just resets back to idle if you try to go higher, its a bit weird. But sometimes on a day when it doesn't feel finicky, it will work all the way up to 10A. Anyway, it let the multiline tube go up to 8.5A, but it only allowed the single line to go to like 4.6A, so I had to wire up a remote to really test the single line.

Does the multiline head stay in tem01 at 10A or does it go back into a nice single-dot tem00??

[CountFunkula]

If memory serves me correctly, it looked like TEM00 at 10A...but I didn't get to REALLY check it out for too long because of the flying sparks.

[buffo]

Welcome to PhotonLexicon, CountFunkula. I see you've already been bitten by the ion laser bug. (Ion lasers may be heavy, cantankerous, and inefficient, but they're still sexy!)

Have you considered attending SELEM 2009? It's about 3 weeks away, and it should be around a 7 hour drive for you. Sounds like a long trip, but trust me when I tell you that it will be worth it. There will be a *lot* of laser gear set up, and you'll get a chance to meet some very cool people. It's a 2-day event, so there's plenty of time for laser shows, meeting people, kibitzing over equipment, more laser shows, beer, good food, more laser shows...

There are a couple members from Ohio that are making the trip; maybe you can caravan with some of them. Have a look at the SELEM threads here and here for more info.

And again, welcome to the forums. Sorry to hear about your recent fireworks, but as others have said, it appears it may be an easy fix. (Bring the head to SELEM and we'll have a look at it!)

Adam

[142laser]

Hi,
If you can figure out the problem with the ML head send it to Sam's laser FAQ for a look and repairs. He is reasonable and will not rip you off. Phil 142laser

PS Does the supply still run the single line head or was the supply damaged? Sparks could mean blown transistors also.

[mixedgas]

Just a reminder guys, JDSU tubes are a 8.O AMP MAXIMUM tube with few exceptions, ie a few 75 and 175 mW heads of which they made very few.

You can push ALC and OMNI to high powers , but most 80-90V tubes such as JDSU/CYONICS/ NEC GLH/SIEMENS/OPTRA/NATIONAL ARE 8 AMP TUBES.

Remember, in general, Power supplies are often generic configured to overdrive a tube, for many reasons. It is up to the systems designer in many cases to ensure the laser stays within the limits, although 10A will not hurt most supplies, I can think of some exceptions, ie the smaller marlin FET supply which maxes out at 8.5A

sTEVE