Author Topic: Need some help with this argon laser  (Read 2452 times)

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Offline bobhaha

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Need some help with this argon laser
« on: August 04, 2012, 08:33:20 am »
So I've pretty much exhausted google, looking for schematics for this argon laser I purchased.

It's a LaserPhysics 50s-488 single line argon laser.

It seems to be having problems producing the low side voltage to heat the cathode. The high voltage "striker" seems to be working fine.

The low side voltage is estimated to be around 3VAC at ~20A. I've checked the board over for blown fuses, burnt out resistors, bulging caps etc.. and it all seems fine.

There are two FET's that I have already changed out, that seems like they control the lowside voltage... but that has not changed anything.

What would be the next step? What do you recommend I try looking at?

Here are some pictures of it....





These components had scorch marks below them...





I changed out those FET's but still no good...

-Adrian
I work with lasers... check out my rainbow http://dl.dropbox.com/u/14298539/BeamShotz/DSC_0009.JPG
 

Offline amyk

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Re: Need some help with this argon laser
« Reply #1 on: August 04, 2012, 01:01:55 pm »
Is the tube OK?

If you can't find a schematic then just trace out the relevant portions. It looks like double-sided and no SMD so it shouldn't be too hard.
 

Offline bobhaha

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Re: Need some help with this argon laser
« Reply #2 on: August 04, 2012, 01:50:54 pm »
Yup, tube was tested... works fine.

The board is 3 layers I believe... this could be a bit of a challenge for me... From those pictures, what would be the first place to sniff around? I'm not sure how I can test the torrid or the small transformer on the lowside... I can get a resistance reading from them... but other than that... I don't know what else to look for in them.
I work with lasers... check out my rainbow http://dl.dropbox.com/u/14298539/BeamShotz/DSC_0009.JPG
 

Offline aargee

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Re: Need some help with this argon laser
« Reply #3 on: August 05, 2012, 06:26:20 am »
Looking at the last photo, your problem may be all/partially caused be the carbonisation of the PCB layers.

You may have resistance paths set up within the board and there's the fault, no matter which components you replace.

Not easy, not hard, just need to be incentivised.
 

Offline bobhaha

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Re: Need some help with this argon laser
« Reply #4 on: August 08, 2012, 04:59:27 am »
Bump... any ideas?
I work with lasers... check out my rainbow http://dl.dropbox.com/u/14298539/BeamShotz/DSC_0009.JPG
 

Offline Psi

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Re: Need some help with this argon laser
« Reply #5 on: August 08, 2012, 05:15:07 am »
Create an account at http://www.photonlexicon.com/forums/ and ask there

They have quite a few people who specialise in knowing everything there is to know about all models of lasers.
I would be shocked if they didn't have the circuit diagram :P

That forum really is a compendium of all laser knowledge and experience.


« Last Edit: August 08, 2012, 10:37:20 am by Psi »
Greek letter 'Psi' (not Pounds per Square Inch)
 

Offline Things

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Re: Need some help with this argon laser
« Reply #6 on: August 08, 2012, 06:43:47 am »
lol, hey boob :D

I believe the board may actually be 4 layers, not 3. Would be kind of a bummer if a trace on the inner layers has burnt out.
 

Offline Gall

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Re: Need some help with this argon laser
« Reply #7 on: August 08, 2012, 10:32:08 am »
That's unlikely. Burning inner traces usually cause visible bubbles. Surface leakage probably.

Regardless of anything you may check the DC operating point and gate and drain signal magnitude. Are they Ok?

Is source going to ground?
The difficult we do today; the impossible takes a little longer.
 

Offline Sionyn

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Re: Need some help with this argon laser
« Reply #8 on: August 08, 2012, 11:07:14 am »
Alex is your man though haven't seen him here for months
eecs guy
 


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