Trying to get an argon running

[DocX]

I recently got a uniphase 2211-20SLE from ebay ...

Looking at the hour meter it appears to have approx. 7000 hours on it

When I initially powered it up it did lase for a second or two, I then switched it off as I don't have fan hooked up.

When I attempted to start it again after a delay I can hear some ticking coming from the head, but it does not light, any suggestions on what could be wrong ?

The filament and thermal cut-out measure as a short / very low resistance so I think they are OK. What should the voltage across the filament be AC or DC ?

Any help would be appreciated!

 

[GooeyGus]

voltage accross the filament should be around 3VDC at 25-ish amps.

If it's clicking but wont light, just let it click. How long did you allow it to click before giving up? Sometimes they take a few tries to get going. If it's clicking it means all your interlocks are good to go and it's trying to start. If it started before, the tube is probably a bit high pressure from sitting around somewhere before you bought it. This is pretty typical. Once you get it started again, let it run for a long time. A few hours at minimum. This will help bring down the pressure and will make it easier to start in the future.

If it still wont start after a minute or two of clicking, you can buy an oudin coil for about $150 that will start it right up. Model BD-10A, I bought one a few months ago and it's the best $150 (actually I paid around $160) I've ever spent. If you plan on really getting into the surplus gas laser thing, it's a must-have

 

[DocX]

I don't get anything across the filament, thick blue and yellow wires.

Is there a common fault in the PSU that I can check for ?

 

[Hemlock_Mike]

With no voltage reading on the heavy wires, there can be no fillament/cathode heat as seen inside like an old radio tube.
If it worked once, check for bad connections, fuses etc. That fillament draws a bunch of current like GG says.

Mike

 

[diachi]

Plug everything in and jump pins 1 and 3 on the remote connection for interlock. make sure the PSU has power to it, but MAKE SURE the emissions key is set to off

Once you have done that, look down the aperture of the laser, and you should be able to see a yellow/orange glow coming from it. If you don't , take off the lid of the head and see if you can see an orange dot being projected onto the metal behind the cathode. If you can't it means that the cathode probably isn't lit.

If that cathode is lit then the tube is probably just high pressured and needs a little kick to get it going .

-Adam

 

[DocX]

Is there any simple way to light the cathode filament to confirm that it is not faulty ?

The PSU I am using is a JDSU 2210U-SL. This seems to work as expected, with the correct jumpers, when I turn the key the PSU fan kicks in, at this point my DMM shows no voltage across the cathode terminals. There is no glow from cathode end of the tube ...

After a delay of around 30-40 seconds the ticking begins, occasionally the tube emits a spot for <1 second.

I have read some of Sams Laser FAQ, but the inside of this PSU is very complex, anywhere I might be able to find a block diagram or schematic ?

 

[daguin]

It sounds like you need to kick it in the tube with an oudin.

Peace,
dave

 

[Event_Horizon]

If it does actually laser for a moment during the clicking, I would just let it click for a while. The tube is very close to lasing; letting it try to start for a while should get it going. I've had that happen with mine if I neglect it for a few months. Turn the power control to maximum (if there is one) while it's trying to start to give it plenty of juice for when it does go.

Also I am not sure what you guys are referring to by filament... If you are talking about the cathode they often run on AC voltage. I know mine runs at 3-5V AC, check for that.

 

[GooeyGus]

are you SURE there is no glow at all before it clicks? Turn all the light off in the room and look in the rear mirror (make sure there is no sticker on it) and you should see an orange glow.  Also, check for continuity across the cathode.

All that powers the cathode is straight AC power put through a transformer, not a very complex circuit there so if it's not lighting its the transformer or a loose connection somewhere.  If you open the power supply, the filament transformer is the big one underneath the main board.  Actually... if it's the newer PSU with the DB-25 connector for the remote interface, just look for the biggest transformer. I'm not as familiar with the internals of those supplies as I haven't really had any trouble with them.

But, without a working cathode, I dont even think you would get little tiny blips of lasing so I would just let it click for a while and see what you get.

Filament = cathode, because the cathode is a big heated filament  

Here are a couple pictures of a typical small argon-ion laser cathode filament. Please ignore the random wires everywhere, I'm in the middle of swapping the umbilical cable to another head

 

[Hemlock_Mike]

Gus --

Nice pictures -- I thought the cathode/fillament was bigger than that.
As we have said, that coil of wire must light up or you're dead in the water.    The reason for the high fillament current is because of the high anode current.  You have to get that 3 volts across the big leads and see the heater's orange glow.   Perhaps a continuity test across the fillament leads  -- I doubt it burned out.

Mike

 

[GooeyGus]

Yeah that filament is on the small side. The filament in my sp168 is about twice that size or bigger, but there's no good way of taking a picture of it because it has a shroud around it.

I have these two pictures, where you can see the orange glow of the cathode. In the second picture, notice how one end of the tube looks pinkish, this is due to the orange cathode glow mixed with the color of the plasma discharge.

 

[Cyparagon]

What model is that smaller one? Do you have any pics of it running?

 

[GooeyGus]

it's a lasos LGK somethin' or other... I dont have any pictures of it running but I will have some soon.

The one in the picture is mine and is high pressure so I haven't gotten it running yet (it lases on the start clicks, so it just needs a good zap with the BD-10A). I have another one here that belongs to Daguin which I will snap some pictures of this week. I'm doing an umbilical swap on the two, since he has a PSU that will work with mine but not his, and I have a PSU that works with his but not mine! Once I finish all the soldering and wiring I'll snap some pictures of it running with the cover off. It's pretty neat to see all the plasma glowing on a little argon.

 

[daguin]

Lasos LGK 7872 ML02 (~40mW) GooeyGus has an ML05, but the tube is the same.

Peace,
dave