Omnichrome 532 Argon help needed.

[jeff]

Hello friends!

I come here to inquire help in troubleshooting my Omni 532 Argon. I have contacted Daguin about my issue and he has referred me to talk with Steve or you guys. I have decided to post here first because I know Steve is a very busy man. Anyway, let's get to the technical stuff.

I bought an Omni 532 Argon off ebay. The seller was selling it as parts/not working as per eBay's policy on non-functional items. The listing mentioned that "the power supply fans turn on, as well as the laser head fan and the hour meter begins moving". I noticed the hour meter read (24.7 hours). It had also been rebuilt by Evergreen Laser Corporation in 2008. So I decided to take a risk and bid, I won.

When the laser arrived it clearly was stored for a long time. However with it being rebuilt in 08 I figured the inside would be nice and crisp. When I opened it, it was clearly nice and clean inside. So I proceeded to attempt to power the laser normally after first checking to make sure everything was wired correctly, the pinouts on the PSU were correct and the fuses were good. Everything looked fine so I turned the PSU on and turned the key. I waited a few minutes and nothing had happened. I grabbed my ARG glasses and proceeded to troubleshoot. My procedure is as follows.

-Check to see if the filament is working, Yes.
-Double check all fuses, All tested good.
-Double check all cables, all look good.
-Listen for starting pulses, I am not too sure about this and think it might be my problem. I can hear starting pulses but the clicking noise normally associated with Argon lasers trying to start is barely audible in this laser. If I had not known what I was listening for, I would have never heard it. I'm not sure if my starter has weak pulses or if they are supposed to be extremely quiet. (Please comment on this if you can).
-Look down the bore to see if any starting pulses are identifiable. I can not see any pulses with or without the glasses on. I can however see the filament glowing.
-Check to see if the tube is gas intact. Tested with an oudin coil, nice purple glow. It seems gas intact.

This is the extent of my testing. I have no further knowledge about Argon lasers to test any further and my knowledge with electronics is very limited. So that is why I decided to post here, hoping you guys could walk me through the procedures of testing this laser and hopefully getting it working. PLEASE be patient with me when trying to explain how to test something if you can as I may have no idea what you're talking about.

Thank you all very much for your help. Here are some photos of the unit itself.

http://i.imgur.com/rrzi9Xv.jpg
http://i.imgur.com/UEjvTJt.jpg
http://i.imgur.com/7wyipN8.jpg
http://i.imgur.com/EU9ysjs.jpg

Edit: Album of top/sideview of PSU.

http://imgur.com/a/m1jFP

[mixedgas]

Since I no longer make money servicing Omni PSUs, who wants to host the 20 page image intensive checkout document for posterity?

The procedure requires a 2 kilowatt, 220V isolation transformer, if you go the oscilloscope route. Its also a bit dangerous if you have never worked on 200 to 800 VDC before.

The other reason I have not posted it, is it encourages newbies to turn one potentiometer they should not, the noise gain potentiometer in the light feedback circuit. This, if misadjusted, causes the supply to oscillate. How to quickly kill a unit and kill your oscilloscope at the same time is something I always avoid publishing.


I'm off shift in four hours, I'll write a further reply then. The OP possibly has a ignite board booster or configuration issue.


Most of what Jeff needs to do are voltmeter steps, not scope steps.

Jeff, do you have a remote or have you wired the 36 pin remote connector for a bypass? That is where we start. Ok, nevermind, I looked at the pics.... Must get back to the day job...



Steve

[jeff]

Thanks for the swift response Steve!

I just wanted to mention that I do not have an oscilloscope. I do however live close to MarioMaster and he has a 50 mhz scope and I have a MASSIVE 200lb isolation transformer. Though I'm not sure when the next time I'll be stopping by his house again. So this isn't an option for me currently. I've talked with him about the issue in the past but I'm getting a bit anxious and I prefer to get all the info and do all the testing I can before we do meet up again.

On a side note, I'm not "too" familar with 200-800 VDC but, I have worked with much higher "possibly" lethal voltages before so I'm aware of the dangers(MOT's, XRAY transformers ect. These aren't DC but still lethal). I don't mind HV but I get really uneasy when the current/voltage are high enough to cause serious injury or possibly kill.

Thanks!
Jeff

[mixedgas]

OK, you have typically up to 980VDC on the start boost multiplier, and what goes to the buck current regulator in the PSU is directly rectified line voltage. Its dangerous.

That said, lets start with the power off diagnostics. Give it five minutes after you unplug before you pop the lid.


Lets start with the fuses, a very good place to start, and move to the Low Voltage DC, The Boost etc.

I need to go take a picture of a main board, brb....

Steve

[jeff]

If it helps any, here is a photo of the guts of my power supply. Its the first time I've opened it since I've gotten the laser. It should have been the first thing I did but its too late to go back in time and change that now.

I don't see any burnt out components nor do I know if anything looks out of place. The power supply hasn't been switched on in about a month so it should be safe to handle for right now.

http://imgur.com/a/m1jFP

[mixedgas]

If it helps any, here is a photo of the guts of my power supply. Its the first time I've opened it since I've gotten the laser. It should have been the first thing I did but its too late to go back in time and change that now.

I don't see any burnt out components nor do I know if anything looks out of place. The power supply hasn't been switched on in about a month so it should be safe to handle for right now.

http://imgur.com/a/m1jFP

It's been hacked. Several of the major connections to the laser head have been crudely spliced inside the PSU. Cathode Leads, Anode lead, and a few others.
I just stared at that photo for five minutes trying to figure out why, what you would need to access by doing that. To no avail. One of the fuses I was going to have you check has been replaced by a jumper. That microfuse was in the gate drive for the Field Effect Transistors, where all the tube current flows.

Don't despair, that does not mean its dead. It looks like some one who did not have access to the proper troubleshooting techniques extended the cables to work on the board outside of the PSU. That is my best guess.

Steve

[jeff]

Okay, so now that we know that someone has messed with the power supply and one of the fuses have been replaced with a jumper. Would that mean we move to testing the low voltage DC? If so, where should I start probing?

Also, if you prefer to move discussion to PM, then I have no problem in doing so.

[mixedgas]

See Attached. We will use it shortly.

Steve

[mixedgas]

See Attached, Docs post # 2 We will use it shortly. If a document has something scratched out or whited out, it is not a adjustment that should be done by a beginner, or requires a expensive HV isolated scope, or is something that will easily kill the Power Fets. This is done for your protection, as these adjustments interact with each other. The adjustments that interact can quickly kill the PSU, resulting in severe board level rework.

Use extreme caution, and a floating, isolated(not USB!) , battery powered voltmeter with a insulated case.

Steve

[mixedgas]

Lets start with the remote connector. Does it match one of the configurations on the paragraph labeled "Normal Operation Check Out" ?????
I prefer the "Current Control" configuration for checkout, because the supply then ignores a bad light feedback opamp or feedback circuit transistor in the head.
Let me know how its wired, this determines how I go about checking things.

DO you hear a cathode heat delay relay click in the PSU at 32-35 seconds after turning the key?

Light Feedback Opamp Head-CA3140 and Head-Q2, the 2N2030 often fail, if the head just winks, this is where I start. Q2 can be replaced by a good quality 2N2222 in a metal can package. These reside in the head. Your head is not even winking, so we need to, well, swap heads. This usually lets me check the ignitor board. But you cant do that, so we need to go backwards and do the whole set of tests.

Is the head "power on" led lit? If so, you probably have good -15V rail

If there is a faint clicking, Q1, The 2N4851 is probably good. That is the other part that usually fails in the head.

Disconnect the umbilical at the PSU end. Give it 5 minutes for the charge on C1 and C2 to bleed off. Check at the PSU end with the head connected, for a short between pins P1-5 and P1-2 from the head. Factory Mods to the head wiring, or the fan connector being off, often disconnect the interlock. This checks the head interlock. 2 to 5 should be shorted. Is it shorted? If head is ALC type, defeat the cover interlock switch by pulling up on the white switch knob.

Check the head current pot, P1-9 and P1-15 and P1-10. If the pot is bad or open, usually the PSU will not fire. Pin P1-15 is the wiper, and it is a 10K pot. Turn the pot, see that the resistance is changing, from wiper to P1-9 and wiper to P1-10.

Disconnect the head. The goal of this test is to check the light detector card (ALC) or light amplifier (532) in the head. Rig up two 9V batteries to provide +and - 9V with a common ground. (use bench supplies if you have them) On the head, Connect the common ground to P1-8, Plus 9V to P1-13, and minus 9 to P1-14, Also Connect your meter ground to P1-8 common, and the meter hot probe to P1-19 feedback. Shine a bright flashlight into the light sensor on the end of the head. You should see a positive voltage that changes, and the voltage depends on your flashlight position. If you can, note the orientation of the light sensor pickoff, use Allens, and remove it from the output coupler to aim in the flashlight. (Do NOT do this with the tube lit when the head is running) If this works, the silicon light feedback sensor, Opamp CA3140, and Q2 in the head are good. If the sensor works, remount it to the head. If the sensor is off and the plasma is lit, the head will surge to the upper current limit and stay there. Normally I use a few spare male CPC pins to do this, not just stick wires in the pins. I can mail you a few if need be.

If, as you say, the head clicks but the tube does not wink, we have a lot of tests to run. Clicks but no winks, can mean: No Boost Voltage, No Boost through 100K, No Anode Voltage, No control circuit, Shorted FETS in the PSU, Bad C1, C13, C14, C2, C10, C4 in the head. Bad Q1 and Q3 in the head, CR1 in the head is open, and a host of things in the PSU. I keep a known good PSU to check the head, and a known good head to check the PSU. Got any friends with a 532? (Don't run over and do the swap, just yet)

This is going to take a while, start with the head interlock. Then move to the +/- 15V supplies in the PSU, per the attached sheets.

Let me know what you find before you proceed to the other tests.

Don't shock yourself! Please don't work alone on Ion Laser Power Supplies, have a safety person near by. If your under 18, I need to advise you not to do this. Wear proper safety goggles.

Steve