JDSU 25ML Argon Help

[Mosc007]

I have a Uniphase 2114 -25ML Power supply and a 2211-25ML Head.

When it arrived I powered it up and it worked. Nice Blue Beam.

After a short time their was a slight electrical burning smell from the power supply. I turned it off and let it sit for a while. Powered it up again the beam came on and the same smell. I turned it off again.

After letting all the voltage drop I opened up the power supply. Straight away i saw a heated mark on the main tube voltage regulator board. I diss-assembled the power supply and checked. It was a 10 volt 5 watt zener that was cooking. I tested it and it's stuffed. This 10 volt zener is the only component on the output of a small bridge rectifier. It appears connected to a toroid on the main ouput circuit. The bridge rectifier meters out fine.

I bought a new 10v 5w zener and installed it. The rest of the power supply looks in excellent condition.

I re-assembled the power supply. Turned it on. Switch in Idle mode and light mode. After the timer it fired up. Low power blue beam. I was carefully sniffing the power supply for anything abnormal. Power supply seemed ok.

After about 30 seconds the beam went out.

Now i can't get it to ignite again. The ignition LED does come on after the timer.

Did some testing.

Filament has 3.4 volts and glows a nice orange colour.
Anode has 176 volts on it while trying to ignite.

I think the igniter is working as about every 2 seconds my meter blinked over scale while measuring the Anode Voltage.


Any help would be appreciated. The tube is 25 years old and power supply 20 years old.


Charles

 

[diachi]

Re: JDSU 35ML Help

I have a Uniphase 2114 -25ML Power supply and a 2211-25ML Head.

When it arrived I powered it up and it worked. Nice Blue Beam.

After a short time their was a slight electrical burning smell from the power supply. I turned it off and let it sit for a while. Powered it up again the beam came on and the same smell. I turned it off again.

After letting all the voltage drop I opened up the power supply. Straight away i saw a heated mark on the main tube voltage regulator board. I diss-assembled the power supply and checked. It was a 10 volt 5 watt zener that was cooking. I tested it and it's stuffed. This 10 volt zener is the only component on the output of a small bridge rectifier. It appears connected to a toroid on the main ouput circuit. The bridge rectifier meters out fine.

I bought a new 10v 5w zener and installed it. The rest of the power supply looks in excellent condition.

I re-assembled the power supply. Turned it on. Switch in Idle mode and light mode. After the timer it fired up. Low power blue beam. I was carefully sniffing the power supply for anything abnormal. Power supply seemed ok.

After about 30 seconds the beam went out.

Now i can't get it to ignite again. The ignition LED does come on after the timer.

Did some testing.

Filament has 3.4 volts and glows a nice orange colour.
Anode has 176 volts on it while trying to ignite.

I think the igniter is working as about every 2 seconds my meter blinked over scale while measuring the Anode Voltage.


Any help would be appreciated. The tube is 26 years old.


Charles

Your filament voltage is high, should be 2.8-3.0VAC and 15-25A with the tube off for the JDSU 2211/2214 tubes.

What's your line voltage? What's the PSU set to for line voltage? Some of them have adjustable taps.

Careful you don't cook your DMM on the starter pulses, or yourself for that matter.

Not sure what tube voltage should be before ignition, at least not off the top of my head... Once lit and running at Iop (8A) it should be around 110VDC...

When the ignitor fires you should hear a tick, and see a flash as the tube lases for a fraction of a second. If you're not seeing the flash/hearing the click we'll need to look at the ignitor too... If the ignitor checks out but there's no flash we'll need to look at tube condition, filament damage etc.

Lets look at line voltage and stuff first ... filament voltage being too far outside of spec for any length of time will damage the tube, possibly permanently.

The FAQ has some troubleshooting tips:

https://www.repairfaq.org/sam/laseratr.htm#atrcttc

And power supply info for 2201/2214:

https://www.repairfaq.org/sam/laserasc.htm#asccu2

 

[Mosc007]

Re: JDSU 35ML Argon Help

Thanks for your reply.

I have the installation manual on the power supply. In the manual it says filament voltage should be 3.1 +/- 0.2 volts. It is high because the power supply is set to 220 volts. I have 240 volts. I did change it to 240 volts when reassembling it. After the tube went out and i coudnt ignite again I put the switch back on 220. I should put it back on 240 and measure filament voltage again. It should come down to spec. But the previous owner has been running it with the voltage set to 220v on a 240v supply.

I diss connected the fan in the head but can't hear the ignitor ticking. I assumed it was working due to my meter flicking overscale every 2 seconds. But maybe the ignitor is working at reduced voltage. The 10uF cap might be gone. I will remove the ignitor board and check it out.

When I started it after the repair I had it in idle mode. Is it possible the tube went out because of the tube age and the idle current to low to maintain the beam ?

 

[Mosc007]

Re: JDSU 35ML Argon Help

Just removed the ignitor board. Removed the 10uF trigger capacitor. Put it on a capacitance meter.

Supposed to be 10 uF. Its reading 1.4 uF. Trigger cap is stuffed. That explains why I didn't hear it ticking and why my meter didn't blow up measuring the Anode volts while it was trying to start. Public holiday today so I will have to wait to get a new one.

This cap is labeled 10 uF 200 Vdc. But it looks to be unipolar.

 

[paul1598419]

Be careful when replacing that cap. I would use one that is set for 104 degrees as these are faster electrolytics and can handle higher frequencies than older caps not rated. If it is indeed a non-polarized electrolytic make sure you use the same one as using a polarized cap in its place will cause worse problems.

 

[Cyparagon]

First, you meant 105°C. Usually I don't correct typos like this, but it makes a big difference when someone is typing this into a search engine to find parts.

Second, there MAY be some semblance of correlation between temperature rating and ESR, but if you're after lower ESR, just get a lower ESR cap instead of trying to guess by the temperature rating.

 

[Mosc007]

It's not an Electrolytic. It's a polyester cap. I have bought 2 different Polyester caps to replace it. One is 250 vdc and the other is 600 vdc. The 600 vdc might be to big to fit but higher voltage rating means higher current rating. I will try tonight when I get home.

 

[paul1598419]

Yes, I hit the 4 by mistake. It sits right next to the 5. Sorry about that. Also, my mistake thinking it was electrolytic. But, most 10 mfd caps are, so it was an honest mistake. Yeah, a 10 mfd 600 VDC polyester cap would be pretty large. That 600 volts is safe voltage it can be charged to without breaking down and doesn't mean more current per se. It means that the cap can be charged to a higher voltage than the lower volt one without breaking down.

 

[Mosc007]

Yes, I hit the 4 by mistake. It sits right next to the 5. Sorry about that. Also, my mistake thinking it was electrolytic. But, most 10 mfd caps are, so it was an honest mistake. Yeah, a 10 mfd 600 VDC polyester cap would be pretty large. That 600 volts is safe voltage it can be charged to without breaking down and doesn't mean more current per se. It means that the cap can be charged to a higher voltage than the lower volt one without breaking down.

Perfectly understandable why you would think it was an Electrolytic. Most high voltage trigger circuits are. The 600 vdc might just fit. Will have to check when I get home tonight.

 

[Mosc007]

I guess that sounded to easy.

I bought new caps. Checked them on my capaitace meter. Guess what ?.... My capacitance meter is wrong. What do I expect from a 30 year old capacitance meter . Put a new cap in anyway. This time I had both fans unplugged and now I can hear the tick tick from the ignitor.

I set voltage switch from 220 to 240. Now filament has 3.07 volts


I suspect this tube has died. It did ignite the other day. After 30 seconds the beam went out.

Maybe the 800 km courier trip to me has damaged the tube ?... Maybe it was slowly leaking ?...

When its trying to start I cant see any ionisation happening.

O well, I got to see an Argon beam for a short time


Only thing left is to zap it with EHT but I suspect its dead.

 

[diachi]

I guess that sounded to easy.

I bought new caps. Checked them on my capaitace meter. Guess what ?.... My capacitance meter is wrong. What do I expect from a 30 year old capacitance meter . Put a new cap in anyway. This time I had both fans unplugged and now I can hear the tick tick from the ignitor.

I set voltage switch from 220 to 240. Now filament has 3.07 volts


I suspect this tube has died. It did ignite the other day. After 30 seconds the beam went out.

Maybe the 800 km courier trip to me has damaged the tube ?... Maybe it was slowly leaking ?...

When its trying to start I cant see any ionisation happening.

O well, I got to see an Argon beam for a short time


Only thing left is to zap it with EHT but I suspect its dead.

How did you check for ionization? Best/safest way is to hold a piece of paper in front of the output when it's trying to start, make sure the room is fairly dark. You should see some of the light from the plasma spilling out onto the paper every time the starter fires, just a little purple(ish) spot. If you're not getting that either the tube is dead or there's some other electrical issue that isn't the capacitor you replaced, either the PSU or something else in the head.

Would be easier to test if you had a second complete unit, that way you could see if the issue is with the PSU or the head.

You've got the PSU plugged directly into the wall, right? Less of an issue at 240V, but the resistance losses in extension cords can cause issues. Probably not that, but that's good to know anyway.

Giving it a zap with an oudin coil would at least help you figure out what sort of state the tube is in (gas mix/pressure). Got a HeNe supply around? That'll work too.

Some more detailed troubleshooting steps from the FAQ:

Preliminary Tests

Even before attempting to get a tube to lase, there are some very basic tests that can be performed to determine if it is even worth building or acquiring a power supply:

• Look for obvious physical damage, signs of serious distress (e.g., melting!), and unusual noise or rattles when shaken. For most tubes made by NEC and some Spectra-Physics models, the visual inspections should be even easier. The gas return tube may be a coiled capillary (possibly very fragile) external to the tube. And, for those with glass end-bells, the filament will be clearly visible from the side.
  
• Inspect the mirrors (inside and outside) for dirt, a metallic coating (due to sputtering), or other damage, and for seriously bent mirror mounts. For tubes with Brewster windows, check these for dirt, a metallic coating (due to sputtering), or other damage.
  
• Check for shorts between the anode (the mirror mount or metal cylinder at the opposite end of the tube from the pair of fat filament studs) and everything else. There should be none.
• Test for ionization. Before powering the filament, it is important to determine that the tube is not up to air or very gassy. Aside from it probably not being worth proceeding if it is, heating the filament would result in oxidation of the tungsten and condensation of white/green stuff onto interior surfaces rendering the tube totally useless. I don't even know if a total refurb would be possible after that sort of abuse. A test for a gassy/up to air tube can be made using a low current high voltage power supply capable of at least 5 kV (e.g., the start voltage from a HeNe laser power supply would work). The idea is to determine if it ionizes with the correct color (purple-white) and breakdown voltage (around 2 to 3 kV for the Cyonics/Uniphase tube, possibly somewhat higher for some of the others). Attach the power supply positive to the anode and the negative to one of the filament leads. Make sure to use a low current supply (a few mA at most)! (A Tesla or Oudin coil can be used to check that the gas ionizes and that the color is correct, but not the voltage.) If these tests fail, at least you have the option of getting the tube rebuilt or using the tube for your own experiments in tube refilling! The filament and optics will still be fine (unless someone before you powered it up in its current state or it was running when the leak occurred.)
  The discharge glow isn't very bright when excited by a low current source like a HeNe laser power supply or Oudin coil - view in a darkened room (but watch out for the HV terminals!). For lasers with external mirrors, it may be easier to see the glow if one of the optics is removed. For example, on the Lexel-88, stick a coin in the slot on the black or silver (depends on model) end of the HR optics mount and turn counter clockwise to remove plug. Then grab the optic with tweezers and gently pull. Note location of O-ring which can be either behind or in front of the optic. Set the optic face down on lens tissue so it won't pick up dust and cover the cavity with a plastic bag when open. The glow is soft violet.
  
• Test the filament. A source (AC or DC doesn't matter for this test) of 2.5 to 3 V at 15 to 25 A is required. (It won't have to run for very long so a little overheating of an underrated transformer is acceptable!). A low voltage high current transformer (e.g., a few turns of heavy wire on a microwave oven transformer with the high voltage winding removed) and Variac will be suitable. Bring up the voltage slowly while looking in through the cathode-end mirror The filament is a thick coil - a single layer solenoid of a few turns - which you will be viewing end-on. Watch as it starts glowing - all turns should stabilize at approximately the same brightness.
  At 2.5 V the filament should be glowing strongly with all turns more or less equally bright. If some turns are dark, the filament is shorted in spots. The tube may still work somewhat, though it may be necessary to limit maximum tube current so as not to overheat the remainder of the filament. The entire filament can be safely brought up to 3 V or till its brightest parts are orange-yellow but don't take it any further.
  For a newer tube, the filament will be well formed, symmetric, and centered. An older or abused filament may exhibit 'droop' or distortion but as long as the central bore is clear, the tube should be capable of lasing. You should be able to see clear through the bore in the center of the filament and out the other end of the tube. In the Cyonics/Uniphase tube, the three (3) gas return holes around the periphery may also be visible.

 

[Mosc007]

Thanks for your help.

I checked for ionisation in a completly dark room while it tried to ignite.

I am almost certain the power supply is working to the state the tube should ignite.

The Igniter board is an "A" revision. Very simple board. A dozen resistors. 2 caps. 1 Fast Diode. 1 PUT and one SCR. And the Toroid. Tested every part and they all check out ok. Reasonably sure iginter board is fine.

Filament has 3.1 vac stable.
Anode voltage is 176 vdc stable. Tested before ignitor toroid so I dont destroy my meter
I can hear the igniter clicking. In a very dark room their is no arcing on the HV anyware.

This is a fully switchmode power supply except filament which is a transformer.

I think next step is an oudin coil which I dont have.

Would an ignition coil from a motor vehicle be ok ? Or to much energy ?

I do have a working HeNe supply for a 6 inch tube.

 

[CurtisOliver]

Can't rep you again yet Diachi, but great advice. :beer:

 

[Mosc007]

Looks like some good news.

I just connected up the HeNe supply to the Argon tube. Had a 75k ballast resistor in my lead.

Beutifull purple glow inside the tube.

Starting to look like the igniter. It is clicking so drive side might be ok. I am wondering about the 500pF 6 KV capacitor on the HV side. No way to test it and not sure were I can get one. Will check tomorrow.

2.30 am here. Looks like more testing to do tomorrow night.

 

[diachi]

Looks like some good news.

I just connected up the HeNe supply to the Argon tube. Had a 75k ballast resistor in my lead.

Beutifull purple glow inside the tube.

2.30 am here. Looks like more testing to do tomorrow night.

That's a good start. I really wouldn't expect a tube just to die outright like that (especially as it was lasing, seemingly well, at first), but an electrical issue could certainly result in a failure like that.

Troubleshooting CU-2214 Starting Problems

The following assumes the use of the 2114 type power supply but should apply with obvious modifications to other models. The only connections that really matter for testing are the Interlock (pins 1 to 3) and Enable (pin 2 to +15 VDC). Make sure the keyswitch on the power supply is set to Run (1). With power applied, the red Power LED and green Interlock LED should be lit and the filament of the tube should heat up for 30 to 40 seconds before the starter is activated. The laser should come on shortly after this, initially at maximum current, then dropping back to the selected setting (Light, Current, or Idle) after a fraction of a second. If this doesn't take place as expected, check the following:

• The orange glow of the filament should be visible through the mirror in the rear end of the tube. If there is a sticker covering the mirror, unplug the laser head from the power supply (to avoid the chance of electric shock) and carefully peel it off. WARNING: Don't stare directly down the bore. Murphy's Law states that the laser will decide to start only if you do this and even the leakage through the HR mirror can be a vision hazard! If there is no glow, check wiring/filament continuity and for filament voltage from the power supply.
• After the 30 to 40 second delay, the starter should produce a periodic "tick-tick-tick" sound until the tube fires.
  
  • If the ticks can be heard but the tube doesn't start or flash (it's safe to turn off the head fan to hear better for this test but remember to turn it back on if the tube does start), either the tube is up to air or has some other damage, or there is a problem with the wiring in the head as the starter runs off the same high voltage DC as the tube. If the tube flashes but won't stay lit, the tube may be high pressure or there may be a problem in the power supply. However, I've found that Cyonics tubes don't care how long they sit on the shelf - if the tube worked last time it was powered, it will probably work now.
  • If there is no ticking sound, check the voltage across pins 2 and 6 of the circular (DIN) connector. There should be 9 to 15 VDC across these pins while the starter is activated. If the voltage is present, there may be a problem in the head electronics or the high voltage DC may not be present at the head. If there is no voltage, there is a cable wiring problem or the power supply isn't issuing the start command for some reason.

Above from this section: https://www.repairfaq.org/sam/laserasc.htm#asccu1

There is more information at that link, pinouts, diagrams for test supplies etc.

Do you have a copy of the full JDSU 2214 manual? IIRC that has complete schematics.

 

[Mosc007]

That's a good start. I really wouldn't expect a tube just to die outright like that (especially as it was lasing, seemingly well, at first), but an electrical issue could certainly result in a failure like that.


[/LIST]


Above from this section: https://www.repairfaq.org/sam/laserasc.htm#asccu1

There is more information at that link, pinouts, diagrams for test supplies etc.

Do you have a copy of the full JDSU 2214 manual? IIRC that has complete schematics.

I only have the full Installation manual from the repair site. The only schematic I have been able to find is the Ignitor board. But its for a later model. I have seen a lot of usefull information on Sam's faq pages. All the connections etc. Don't think I will have much luck finding full schematics for the power supply.

I will keep working on it. Seeing the purple glow has given me some confidence the tube is ok.