Omnichrome HeCd Laser - need help....NOW FIXED!!!

[diachi]

Re: Omnichrome HeCd Laser - need help

That is one overly complicated switchmode power supply!!

As it have led´s for error codes its likely microprocessor controlled, and then fixing it is likely as good as impossible.

Sorry mate.

It needs to be complicated in order to control the cadmium pressure and helium pressure. If the pressures are incorrect then you won't get any lasing - or very little anyway. There is yet more circuitry required to control everything else, tube voltage, filament voltage. Things like that.

Well done for noticing that it's switchmode! Once again things get complicated - tube voltages on these are somwhere around 1.5kV , currents can reach 90mA ... my Model 74 took 2.6kVDC @ 96mA.


My figures were probably off a bit - I never actually calculated the current draw ... just went with the label that said 10A. So 10A @ 240V = 2.4kW

 

[Experimentonomen]

Re: Omnichrome HeCd Laser - need help

Without a schematic and a service manual, this thing will be impossible to fix.

However the filament error code could indicate something wrong in the filament current sense part making it think the filament is broken.

Or that the cpu aint getting any signal for the filament voltage/current.
It could even be the cpu itself have failed.

Im no expert and have very limited knowlege in switchmode power supplies so i dont have a clue, these are just possible ideas.

 

[timelablasers]

Re: Omnichrome HeCd Laser - need help

Problem FIXED!!!!!
After months of looking through the laser head and power supply with a completely puzzled look on my face, putting it away, coming back to it, giving up again and so on.....I have finally found the problem and the laser is now working sweetly.
The problem was so simple. A wire inside the head was pressed up against and rubbed through to the tube chassis creating a short and returning an error to the PSU. Moved the wire.....problem solved. Wow! And to think I almost gave up on this thing entirely. It was very close to having the tube removed for display purposes and the rest being scrapped.
Many thanks goes to the guys in this thread who generously offered their knowledge and expertise as much as they could via this thread and through emails, especially diachi and Sam from Laser FAQs.
Photos of the now working HeCd will be coming soon.

 

[SpyderFire]

Let me guess... you fixed it !?

http://laserpointerforums.com/f51/fixed-omnichrome-hecd-laser-pics-51244.html

 

[timelablasers]

Yeah! It took me months to find the problem. Once found, it took me 30 seconds to fix.

 

[timelablasers]

OK....some photos of it working....
You can just see part of the glowing laser tube through the cooling slits.

The beam looks almost completely clean in reality and is a purple colour.., but not so through the camera lens.

Very hard to pick up the actual colour of the laser light with the camera.

Looking towards the tube output end

 

[SpyderFire]

What is the approximate wavelegnth measure on it?


I'm glad you got it working for less than expected.

 

[Prototype]

I believe HeCd's lase somewhere around 440nm.

 

[HumanSymphony]

I believe HeCd's lase somewhere around 440nm.

442nm to be precise and 325nm with the right optics.

 

[millirad]

Good job on getting a very difficult and beautiful laser running. The beam profile isn't going to be much over 1.0 milliradians is it?

 

[timelablasers]

Good job on getting a very difficult and beautiful laser running. The beam profile isn't going to be much over 1.0 milliradians is it?

Thanks!
The manual specifies 1.5mrad.

 

[Andres David Velez]

Re: Omnichrome HeCd Laser -

Good afternoon

I have an HeCd Omnichrome laser. Laser head is a Series 56 and the power supply is an LC-500. the problem is that I have the cable that connects the source with the laser, I have only needed the cable connectors, if you know where I can get it or the configuration of this cable would be helpful

 

[Andres David Velez]

Good afternoon

I have an HeCd Omnichrome laser. Laser head is a Series 56 and the power supply is an LC-500. the problem is that I have the cable that connects the source with the laser, I have only needed the cable connectors, if you know where I can get it or the configuration of this cable would be helpful

 

[Andres David Velez]

Good afternoon

I have an HeCd Omnichrome laser. Laser head is a Series 56 and the power supply is an LC-500. the problem is that I have the cable that connects the source with the laser, I have only needed the cable connectors, if you know where I can get it or the configuration of this cable would be helpful

 

[timelablasers]

Good afternoon

I have an HeCd Omnichrome laser. Laser head is a Series 56 and the power supply is an LC-500. the problem is that I have the cable that connects the source with the laser, I have only needed the cable connectors, if you know where I can get it or the configuration of this cable would be helpful

Hi,
This might be a hard one. If the connectors are a 'standard' type, then you might be able to source them at a very good electronics store. But if they are proprietary, you may have to contact Melles Griot directly or replace them with standard type connectors. Be aware of the dangers associated with the high voltage connectors and the importance of ensuring they are safe.