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ArcticMyst Security by Avery

Lasos Start-up problem

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I have a Lasos 40 mW ML head with with a Cyonics 2102 PS. The last two nights, it light up with about 3 pulses. Tonight, it won't lase after 40 pulses. Is there a fuse inside that might be blown? The exterior 3 Amp fuse is OK.

HMike
 





diachi

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I have a Lasos 40 mW ML head with with a Cyonics 2102 PS. The last two nights, it light up with about 3 pulses. Tonight, it won't lase after 40 pulses. Is there a fuse inside that might be blown? The exterior 3 Amp fuse is OK.

HMike

Check to see if there is any voltage across the tube before it lights and work from there.

I doubt it's gone up to air - but it may be worth while to test and make sure. You should be able to test that easily anyway as IIRC Lasos tubes have the glass end bell, so it will be easy to see any ionization occurring.
 
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Does the anode voltage turn on right away -- before the ignitor circuit fires?
HMike
 

diachi

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I believe it does. It may have a voltage of around 150VDC across it which then goes down when the arc is struck with the HV pulse from the starter card. Similar to the way a xenon flash lamp works in a strobe or camera with a voltage across a tube before it actually flashes.
 
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That's what I was looking for. I guessed about 150 VDC which will ballast down with a current regulator once the arc starts. I don't want my meter (or me) in there when the ignitor hits:-(

HMike
 

daguin

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I have one Lasos head that takes many pulses to fire. I figure that every time it does that I lose a bit more cathode material :(

Peace,
dave
 
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Dave -- That's what scares me. One night it lights up on the second pulse and the next night, no lase.
I just measured -57 volts from what I think is the Anode lead to ground. That doesn't look right. Maybe the cathode floats above case ground. I was expecting ~+ 130 to 180 VDC on there waiting for the spark.

Mike
 
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Dave --

The numbers on the head are: LGK 7872 ML02
Rated 48 mW

I'm looking to find out if there's a stupid fuse blown inside. The external 3 amp fuse is OK but there has to be some fuse rated 8 to 10 Amps somewhere.

HMike
 
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daguin

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Dave --
The numbers on the head are: LGK 7872 ML02
Rated 48 mW
I'm looking to find out if there's a stupid fuse blown inside. The external 3 amp fuse is OK but there has to be some fuse rated 8 to 10 Amps somewhere.
HMike

If it remains a mystery, I can ship you another head or you can ship me yours to see which component the problem is in.

Peace,
dave
 
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I measured the anode voltage today. Before the ignitor starts, I read ~120 VDC - anode to cathode. I'm getting good flashes but no arc. All the red led's inside come on.

HMike
 
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Chris ---
I have a BIG variac. I'll try it. It was working so well as a room heater for a couple nights !!

Mike

Update --- I put a 10 Amp Variac on it and all it did was speed up the start pulses and a little brighter flash but still no ignition. The cathode also got brighter too -- the higher emissivity should have also helped light it up. It was a good idea however.

Preheat with a hair dryer??
 
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Chris --

A little warm air and 140 VAC for a moment and it's running again on straight line voltage.
I thought I'd lost my ML Argon............
Thanks guys for the help.

Hmike

Can I be running too much fan for cooling? I don't think so but I believe they need to run a little WARM. I can easily touch the glass area around the hot cathode.
 
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No, I'm almost certain the cooler the better. Otherwise, we wouldn't have units that pump 40 degree tap water around the tube.

Also, you probably shouldn't be sticking your hands in there when it's running :)
 
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Cypa -----

I've worked with MUCH more dangerous voltages than this 40 years ago!!! This laser isnt as scarry as working on a CO2---------

Rule1 -- always keep one hand behind your back.

HMike

Aahhhhh -- It's cold here and my 1 KW room heater is assembeled and running again. I love the 8 bars of color! Thanks to my fellow laserists for the help and suggestions.
 
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