Firing up a little argon?

OK well, I just stuck the HV lead of the CO2 power supply just far enough from the cooling fins so it wouldnt arc, fired up the argon PSU and slowly brought up the CO2 PSU. I could SEE corona jumping from the CO2 lead to the cooling fins, but the argon still refused to light

With these PSU's, are they actually looking for any feedback from the start board before they let the full current through? The only wires I have connected from the PSU to the head are the anode(black), the 2 cathode (blue and yellow), and the 2 orange interlock wires shorted. The light sensor plug, as well as the start board wires aren't connected to anything.

I think they default to max current for a split-second, then dial back to what you have it set at. Try starting it with max current setting.

Tried starting it at max current, no luck

With the high voltage, would the ground wire have to go the filament end, so that the arc jumped from anode to cathode instead of the shortest way to ground?

Heres what I've established so far:

The filament is working
The ignitor is working
The ignitor is successfully striking an arc in the tube
When it does, the tube does lase
The power supply isn't showing any clear signs of shorted circuits
I briefly connected my DMM up to the anode and cathode, and saw 180V floating.
The PSU is wired to run at a higher current than idle
I'm NOT using the starter board for this PSU, however the starter board does not seem to have feedback anyway, so shouldnt matter

And for some reason, it just cant maintain the arc when it tries to strike.
Cheers,
Dan

I don't know the exact model you have, but i already seen one, times ago, that had a safety part of the circuitry hooked to the power measure diode, that was turning off the laser if the power signal was not present or failing ..... are you sure that your PSU don't have the same feature ?

Do you have the schematic of the PSU, for check this thing ?

The PSU is a Uniphase 2111, which I can't really get much information on. Apparently it's pretty identical to the 2214, which is what I've been getting info for. There is a possibility there are differences between the 2 PSU's that I'm missing.


EDIT: I found the user manual for this laser. Could someone help me understand which pins need to go to what? I followed the 2214 pinout on Sams FAQ to wire it up as it is currently, though there may be differences between the 2214 and 2111?



Cheers,
Dan

That table does not look too much clear (fire the employee that wrote it ), but can try to guess .....

Pin 11 seem the common GND for the signals .....

Pins 6 and 7 appears to be inputs ..... a voltage on pin 7 control the power, a voltage on pin 6 control the laser current (this, at least, is as it appear reading the descriptions)

Pins 8 and 9 are monitor outputs ..... on pin 8 you have 30mV for each mW emitted (power monitor), and on pin 9 you have 100mV for each A flowing in the tube (still pin 11 as common GND)

Pins 2, 4 and 5 appears to be status outputs, from the description, but i have a doubt about this ..... the manual say "pin x IS at ....." and this usually means output, but as far as i remember, those pins are all inputs ..... i mean, on other models, grounding pin 2, turn discharge off, when placing it at +V (pin 13), turn it on ..... grounding pin 4 turn the laser in idle mode, placing it at +V turn it in work mode ..... grounding pin 5 set the PSU working in current control status, placing it on +V set the PSU working in power control status ..... it's very strange that on that table they are indicated as if they was outputs, instead inputs .....

Interlock is 1-3

Have you tried to hook a DMM on the monitor outputs for see if the values are corrects ?

Another thing ..... i suppose you don't have a current or power control hooked at the laser, so, are you using the pin 4 ? ..... i mean, maybe forcing the system in idle mode (grounding pin 4 to 11), will ignore the fact that you don't have a driving signal for the power control, and fire the laser stable in idle mode ..... just a speculation, but can worth to try it .....

Yeah, it matches the user interface to the 2214 PSU (which I've been following).

Pin 2 connected to 15V will allow the laser to try fire - Done that
Pins 1 and 3 connected together for interlock - done that
A pot connected to pin 6 for current mode - done
Pin 4 connected to +15V for run mode - done
Pin 5 connected to ground for current mode - done

And yet it still doesn't wanna stay lit

I just tried hooking pin 4 to ground and it didn't do anything i don't think. Neither does trying to increase the current. Really wish I lived close to someone with an oudin coil, just so I can put that theory to rest (or get the thing going if its all it needs)

One thing I have noticed though, is every time the tube tries to fire, there is a click in the power supply. I am _assuming_ this is some sort of high voltage back protection from the PSU, although it kind of does sound like a relay also. Is it possible the PSU may have some kind of high voltage kickback protection which is stopping the tube from getting any power?

Here is a recording of the PSU clicking noise: http://www.youtube.com/watch?v=xcIUpimiPWY

And another video of it trying to start: http://www.youtube.com/watch?v=6gYcAA-aCQQ

Cheers,
Dan

OK, I just connected up the starter designed for this PSU. The pulse rate is much faster, however, still no go

I haven't posted because I really would not be of much help,
Although I did find an oudin coil that you might be able to get a bit cheaper.
Worth a gander at least:beer:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=260741106557&ssPageName=STRK:MEWAX:IT#ht_7997wt_905

Alright well, I've stuck my eeepc out with the argon with the camera on, and I'm watching it thru VNC in my airconditioned room

I do feel as though its trying to get somewhere. When I turn the current up, the click gets a bit deeper, and occasionally you get a bright flash with a different tone. Will running it continually trying to start damage anything? Or will it even help?

Cheers,
Dan

AWESOME NEWS: IT WORKS

I left it trying to start for like 40 minutes, and came back to it and ramped the current up a bit, I saw a bright flash, but it was still trying, ramped it up a tiny bit more, and BAM, it stayed lit! I could then run it down to idle

The bad news is, my temp fan setup couldn't keep the temp under control, and it hit 90C very quickly. I'm not really sure what the safe temps of these lasers are, but I didin't want to push it. So I had to turn it off. I tried starting it again and it lit like 4 clicks later, so success

Congratulations!!!!:beer:
If the temperature is out of line there should be a automatic shutdown for it.(at least my non-working head had one...I think its standard)
Have fun and good luck....get a better fan and play for hours on end!

It does have an automatic shutdown sensor, however everything is just bodged together on the table at the moment, so it isn't connected. The heat off this thing on idle alone is CRAZY!!

So, news of the day: If your argon won't start, and you don't have anything HV to kick it up the ass with, run it on idle and let it spark for a while (Many hours) and keep trying

Pictures and videos incoming

Cheers,
Dan

Things said:

Will running it continually trying to start damage anything? Or will it even help?

Click to expand...

Yeah, that's bad. Every pulse sputters some of the cathode material.
You didn't have many alternatives though. Maybe letting just the cathode heat the tube.

My guess is that the heat from the cathode eventually drove just enough of the gas away to let it start.
What is the tube voltage now?

Ah well, I'm happy its running now

Still takes a little effort to get it started, but it always starts when I ramp up the current a bit now.

How long should I leave it idling for to try get the pressure back down?

Got some vids coming, but a few pics:









Beam is a fair bit greener in real life.



Will the beam change back to a more bluish colour as the argon gets itself back into line?

Also, it seems I'm going to need a much more powerful fan. Does anyone have any recommendations for a (preferably cheap) 240V. very high flow 120mm fan?

Cheers,
Dan

Glad to see it work again :beer: