Argon Ticking

I believe I actually have this in light mode, just controlled via the power adjustment knob on the PSU (jumpered pins 2 and 3). The output power is very steady. The laser head has a 0.2V/A conversion factor imprinted on it just above the red/black jacks. Will the fact that the laser is running in light mode vs current mode change my readings/which jacks to use? One set of jacks is red/black, the other set is blue/yellow. Both indicate a 0.2V/A conversion factor.

I've turned her off since, she is getting started pretty much normally now (if it doesn't light up the first tick, it lights up on the second tick). Now I'm more concerned with overheating the tube, because my fan is rated at 120CFM (not to mention, the fan connection is loose somewhere, still have to go resecure all of the connectors).

How do I measure the tube voltage safely? Where should I place the DMM leads, etc? I'm pretty sure the tube is near the end of it's life, given how old this tube is (catenodes). But, I will check, once I have some clearer instructions on how to without zapping myself Thanks

EDIT: 1500th post! :san:

One way to judge how well your fan is cooling is by how hot the air is coming out the exhaust. If the fan is pulling too much, 500CFM for example, the air is cool to the touch. To cool, in my opinion, because the laser operates more efficiently when it is hotter. If it isn't blowing enough, 50CFM for example, then the air will feel really hot, maybe too hot.

As long as the air coming out the exhaust isn't cooking hot for the given operating current, then I wouldn't stress about it. Others can chime in, but a nice toasty 80F-100F warm is what you're shooting for. And test at your median operating current, such as 6 or 7 Amps. Because at idle she runs cooler, and cranked all the way, the air will be HOT.

I have heard light mode is harder on the tube and PSU because current is constantly changing trying to keep the light output the same. If she is starting normally, you are beyond the hurdle, so it won't matter now. But in my opinion, it is better to operate her at constant current (mode), and allow the light output to fluctuate a tiny bit. For a healthy tube, the light will not fluctuate all that much for a given current, so light mode isn't as hard on things as it might be when you're bringing one back from storage.

I use a little meat probe in the exhaust path and try to maintain
about 140 DegF. Sometimes I will let it climb to 160 for a short time.
I control the temp with pieces of paper limiting intake air in the middle
of the vents. Monitor it until your desired temp is stable.
HMike

Glad to see you got it running! I don't recall an easy way to test tube voltage on a 60x. In the past I just take the cover off and attach the negative lead to the cathode, let it start and carefully touch the anode with the positive lead. I wouldn't let it run longer than 10-12 seconds though. And don't touch the meter lead to the anode until after you're sure it's started. Some meters don't take kindly to the start pulse!

I just want to clarify on where exactly I should be placing the leads when testing the tube voltage, should I place them where the wire connectors to the laser tube are, or should I place them near the heatsinking fins like the Oudin coil placement, or elsewhere?

Thanks

Update: alright I hooked up a 10k pot, CCW to pin 1, CW to pin 25, wiper to pin 6. Hooked up my DMM to the yellow/blue jacks (those are labeled "laser power", I was using red/black jacks before, that one said "tube current" :thinking I'm getting min is .15V, max 3.8V (0.2v/A, so .75A to 19A range). Running the tube at 2V I'm getting all eight lines, but no time today to get output power measurements in. I break the 2 line output barrier at .26V, 2 lines to 6 lines is rapid, but it's the blue end that comes in, the 514nm line pops in at .72V (7th line), and the 502nm line pops in at 1.53V or so (need to check that one again but I believe that's where it was, 8th line).

Still looking for some info on measuring tube voltage, but .15V for min? That's less than 1A... isn't idle around 4A-5A?

EDIT: also, 3.8V translates to 19 amps... :thinking: isn't 16 amps the absolute max on these PSU's?

EDIT #2: are these fans good? How should I mount this to my laser? Are there better options out there? http://www.amazon.com/Squirrel-Cage-Fans-180-CFM/dp/B0012BFC6I or http://www.amazon.com/Active-Air-ACF180-Blower-System/dp/B004K5WW7U

EDIT #3: or is something like this better? http://www.ebay.com/itm/151001639959

Anyone have any idea about my current range? I took the readings without pressing the white button down... Sam's Laser FAQ mentioned that laser power was inaccurate over 20mW... so now I'm confused as to what those readings were. The head notes 0.2V/mW on the blue/yellow jacks.

Any help with the fans is much appreciated

Regarding fan types:

It is my opinion squirrel cage fans are ideal if you're pulling air from the head using ducting, be it flexible or hard ducting. Those 60X heads are better equipped using a box fan screwed directly to the head.

It keeps things compact. The opening is above the head, and in the Xerox machines, there was an air box pulling air from the top and towards the rear. That box was bulky and is often discarded.

The JDS 221x heads are shaped different. They are cylindrical and flexible ducting is typically affixed to the rear. In those configurations, squirrel cages work out great.

But for your ALC 60x head, I recommend a box fan, be it square or round, of the right diameter and CFM rating screwed right to the top of the head.

Regarding current readings and your PSU:

One amp seems implausible to be idling at. It seems unlikely the PSU could even be configured to output so little. Further, we rely on the PSU to accurately and proportionally provide the scaled meter reading of its output. I am still suspicious of your PSU and I would be careful putting too much trust in the readings you are seeing. Of course, I am presuming there isn't some obvious flaw in the manner in which you're taking your readings. It isn't rocket science, so I'm presuming your meter readings are not to blame.

Do you have any suggestions for box fans?

Well I am confused as to how these jacks are supposed to be used, I got those readings by sticking the leads into the blue/yellow jacks. Apparently though Sam's Laser FAQ says I need to press the white button on the laser head and then take readings, but it's not very clear. I think that's what it's saying though, so I'll have to look into this.

Choosing a fan is easier than you think.

Recall from post number #134?

Begin at this site:

Axial Fans - Cooling Fans and Accessories - Grainger Industrial Supply

Scroll through the list and look at the specs.
Find a fan that meets your specs.

take some measurements on your head and identify the size fan you want.
locate where the power will come from and measure what voltage it is.
with that, and your desired CFM requirements, choose a fan that best suits your needs.

Grainger is pricy. But once you know what you're looking for, look on ebay, amazon and other sources on the net for the right fan to fit your budget.

Once you identify the Dayton part # of the fan you want, finding one cheaply is your next goal.

How's this? DAYTON Axial Fan, 115VAC, 6-3/4In H, 5-15/16In W - Axial Fans - 2RTK7|2RTK7 - Grainger Industrial Supply

I think the ALC has a 4" by 4" square opening for the fan, I didn't see any square fans on Grainger in the 200CFM range that wasn't $700+

The fan above seems to have almost a 6" diameter fan, is that too wide for my ALC?

Also, should I want 200+CFM as Sam's Laser FAQ indicates, or is ~180CFM enough? Right now I'm just searching for fans between 150CFM and 280CFM

I just tried measuring the tube current again, I still cannot get the red/black jacks to give out an output. I'm getting from -0.2V to 0.2V, constantly fluctuating, usually around -.07V or .07V :thinking: could it be outputting AC? I'm using the DC setting on my DMM at the moment

Using the yellow/blue jacks, I'm getting 0.1V on min current, and 3.24V on max current. The white test button has no effect on either set of jacks.

The red/black jacks measure 8.3V to 9.2V AC, independent of the pot setting. It is also independent from pressing the white test button or not. The blue/yellow jacks are measuring .12V to 3.48V DC today. It seems the upper bound is a different number every time I turn it on :thinking:

Also, my ALC has a cutout at the top that measures about 3.5" by 2.6" for the fan. The fan mounting screws are located about 3.42" from the edges of the cutout, one near the front of the laser and one near the back. Grainger doesn't mention where the mounting screws are, only the overall fan dimensions. Any ideas? Thanks

UPDATE: measured across the heatsink fins, where the Oudin coil would be placed, I am getting around a 95V drop. It fluctuates though, occasionally I get a brief reading as low as 60V, but usually around 75V, mostly stable at 88V, or sometimes reading 95V. I'm still not exactly sure this is where I should be measuring the voltage drop across the tube though :thinking:

EDIT: This is at minimum setting on the pot

EDIT: at 2VDC on the yellow/blue jacks (which says 0.2V/A, so this should be 10A), I'm getting a reading of 102.3VDC when I put the two DMM leads on the catenode connectors. I do believe this Argon needs to have its mirrors tweaked a bit though, lots of research to do

I don't imagine it's easy measuring current and cooling the laser at the some time.
you may need to attach leads and reassemble the head so you can run her for a time.
I would imagine at startup, and as she warms up, there is some fluctuation in both current and voltage.
if the DC voltage readings you're seeing can be believed, operating under 100VDC is really quite good.
but operating as low as 60VDC seems unlikely, so it's possible you're not measuring at the right place.
10A current should be cranking out the heat and the output power.
do you have an LPM? do the current readings correlate with the output power?
if not, the current reading at the test points may be unreliable.

Wait I thought 101V was a dying tube, 115V is overfilled tube? I did have the head reassembled at the time of taking those measurements.

Yes the fan is blowing out pretty hot air at 10A (or so I am led to believe), I have 7 lines at 10A. I am still getting a range of .12V to about 3.4V on those test jacks, so I'm not sure if this is entirely accurate... .12V just seems too low, that's .5A

The LPM readings do rise as the measured voltage on those test jacks rises, is there is specific relationship I should be looking for? The over current led was at about 70% brightness when I was taking those measurements yesterday, is 10A near over current for the tube according to xerox?