Dead (?) Argon Laser Help...

[danielbriggs]

I took my argon laser to UKLM in Surfleet, and it happily ran all of Saturday (with several breaks, but probably for about 8 hours overall), kicking out 20.4mW steady.
It's a JDSU 2214-20SL head and 2211 PSU.

Come Sunday, tried to power it up, after the 20 second delay I got a blue beam flash, and then it switched off. About 30 secs later, I'm guessing another start pulse was issued and the blue flash repeated. I switched it off as something was clearly wrong
Tried a few more times throughout the day, and it was exactly the same

So, does anyone have any idea as to how I can fix it?
I reckon it didn't like the long run times (it usually get about 1-2 hours per month). I hope 8 hours in one day didn't kill it. Either that or I accidentally dropped a Jaffa cake / HobNob in the PSU

Cheers,
Dan

[GooeyGus]

That sure is weird. Maybe try measuring voltage across the tube after it has tried to start and see if the voltage is there, should be about 150vdc if it's not running. If the voltage is there but it won't stay lit, it could be an issue with the little starter board.

I would start there since it's the easiest. Does the tube only lase for a very short second, Like the duration of the start pulse, or does it stay on for a couple seconds then shut off? Does it only click once or are there repeated clicks in a row?

[danielbriggs]

I'll check the voltages tomorrow night, as it's all packed away in the garage.
Yes, the tube lases for about 1/2 a second or less. It's certainly not a few seconds.
It goes something like this: Turn key, Wait 20 seconds, single click + 488nm line appears very briefly (<0.5 seconds), lasing stops, wait ~30 seconds, single click another flash, wait 30 seconds etc....

It's like it's trying to start, get's going with a beam, but doesn't sustain the beam, and then the PSU tries again.

[GooeyGus]

I'll check the voltages tomorrow night, as it's all packed away in the garage.
Yes, the tube lases for about 1/2 a second or less. It's certainly not a few seconds.
It goes something like this: Turn key, Wait 20 seconds, single click + 488nm line appears very briefly (<0.5 seconds), lasing stops, wait ~30 seconds, single click another flash, wait 30 seconds etc....

It's like it's trying to start, get's going with a beam, but doesn't sustain the beam, and then the PSU tries again.

Yeah it could be a starter issue. Do you have a tesla coil or anything similar? You could give it a jump start and if it sustains you'll know its a starter issue.

[Vidal Wolf]

It sounds like the start circuit is fine.
The tiny flash of light your getting is from the start circuit firing,and ionizing your tube,but the power supply main isnt able to *latch on* and sustain the ionization .It really sounds like a gas pressure issue.
Ive had several air cooled ions that have been temperamental and when they get to the end of life,they would have *hard start* issues.
Were you running the head at max power? you can eat up the life on the smaller ions really fast when they are run maxed out and for a long period.
try placing the head in the fridge or freezer for an afternoon and then trying to re start it while its cold,being carefull of condensation issues of course!
It can change the gas pressure in the tube,and might get it to re strike sucessfully.

[danielbriggs]

Thanks for the suggestions!

It was running at it's rated output of 20mW for 8 hours, roughly 2 hours on, 1 off, 2 hours on etc...
I'll give it one more try now, and if not I'll put it in the fridge over night.
I've put many a hard drive in the freezer, but never a laser!

GooeyGus; Unfortunatly I don't have a tesla coil to try

I will certainly keep you both posted.

[GooeyGus]

It sounds like the start circuit is fine.
The tiny flash of light your getting is from the start circuit firing,and ionizing your tube,but the power supply main isnt able to *latch on* and sustain the ionization .It really sounds like a gas pressure issue.
Ive had several air cooled ions that have been temperamental and when they get to the end of life,they would have *hard start* issues.
Were you running the head at max power? you can eat up the life on the smaller ions really fast when they are run maxed out and for a long period.
try placing the head in the fridge or freezer for an afternoon and then trying to re start it while its cold,being carefull of condensation issues of course!
It can change the gas pressure in the tube,and might get it to re strike sucessfully.

Yeah but the start circuit should continue to fire until the tube maintains.

I really dont think it is a pressure issue. I've also had many tubes at end of life due to extreme high pressure and low pressure. The low pressure tubes would start and run just fine, but would usually be missing the green lines. The pressure tubes will click and click and click trying to start.

This is why I think it could be a starter issue. It shouldn't just click once and give up. I had a tube that would lase when the starter clicked, but the tube just couldn't maintain that arc, but the starter would click for hours if I let it go. Finally I zapped it with a BD-10A and it was fine.

If one of the capacitors on your starter board died, it would only be able to click just once with a weak pulse, rather than rapid clicking.

That's just my opinion though

[danielbriggs]

OK, this is weird.
I've just powered it up, and it worked fine

It has been sat in it's box in my boot for the last week. Either the cold nights or the many miles has fixed it

Could this be a sign that either the tube is dying or the capacitors are dying?

Cheers,
Dan

[GooeyGus]

OK, this is weird.
I've just powered it up, and it worked fine

It has been sat in it's box in my boot for the last week. Either the cold nights or the many miles has fixed it

Could this be a sign that either the tube is dying or the capacitors are dying?

Cheers,
Dan

I'd guess that your tube is fine

[mixedgas]

look, test the psu with a known good head.

Then find someone with a BD10 if the psu checks out

PV = NRT Delta PV = Delta NRT, 1->20'C = a joke measured in millitorr. Dont bother freezing with anything, not enough pressure change to matter short of LN2, and if you cool a cyonics/uniphase design to Liquid nitrogen temps,ignition is the least of your problems when the mirrors crack off from the seals shrinking.

Steve