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Laser power supply identification

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McFluffin

Sat Apr 01 2006, 09:44PM

Registered Member #119 Joined: Fri Feb 10 2006, 06:26AM
Location: USA
Posts: 114

I raided a cool garage sale that was in a warehouse. They needed to get rid of stuff and so everything was basically a dollar. Among the things I got for a dollar were a pile of transformers, a WiFi card, and a fairly large laser power supply:

However, I really don't know a lot about these, so I'm not sure exactly what its for. My thought is that its for a CO2 laser. It says 18000 volts on the outside of it and has a 6 pin connector on the output:

However, the top of the unit rates it at around 2200V or so:

There is an input, but it isn't really labeled what they are for. There are three connectors. I was thinking perhaps one was for startup voltage, one for regular operation voltage, and the other is common?

Anyway, it has "WARNING" written in 8 languages, so it must be something interesting. :) If anyone could tell me what type of laser this goes to, I'd be very happy. If you happened to have a laser to go with it, that would make me even happier. I figure its a nice HV DC power supply in any case. I tend to remember laser power supplies are very clean in their output.
On a side note, heres a couple of pictures of a HV transformer I also picked up if anyone can tell me something interesting about it. It reminds me of something you'd see in a transformer station.

I also just got that stuff in, and including, that blue crate. Excuse the messy table...

mikeselectricstuff

Sat Apr 01 2006, 11:17PM

Registered Member #311 Joined: Sun Mar 12 2006, 08:28PM
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Posts: 253

That voltage would be in the ballpark for either a Helium-Neon or a small Co2 laser

...

Sun Apr 02 2006, 08:01PM

Registered Member #56 Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2445

Is there any way to get inside of it? You could then trace out the pins and figure what is going on...

The input connector seems like it is a ground and two power lines, but whether you hook up 120 or 240 to it and where... My guess would be that they are the two primaries of a transformer so you could put 120 into one of them, or 240 across both...

One of them is probably connected to the case (that would go to ground), and from there you could try hooking a variac up to the other ones until you see signs of life... One the lights come on you could then start probing the output and see what is available there. I have a feeling there is some kind of interconnect that has to be activated; but that connector on the front looks like it might have already solved that problem.

That transformer at the end...

I have a hunch that it is a shunt that would be put in series with a big line (using those huge terminals) and then the smaller ones giving a signal proportional to the line current...

In any case; score!

McFluffin

Sun Apr 02 2006, 10:49PM

Registered Member #119 Joined: Fri Feb 10 2006, 06:26AM
Location: USA
Posts: 114

Thanks for the replies. Based on the ratings, I was thinking it might have been one of those types of tubes, but the front 18,000V stickers and its size make me wonder when I've seen supplies for HeNe lasers that are only a couple inches on each side. Perhaps this is so much bigger because its 20 years old?
"...", there is a plug in the upper right for selecting the input voltage and it is currently set at 115. Its circled in red in the attached picture and is labled "INPUT VOLTAGE PROGRAM PLUG." Is this what you were referring to by transformer? The voltage goes in into the plug circled in green. There are three pins on that.
I'm probably going to have to use some vice grips to get out the screws. They use a star head with a raised center for which I don't have a socket for. I wanted to open it earlier to get a better idea, but thought I'd wait until I at least asked my dad if he had something that would fit that(he didn't). Maybe I can go down to the hardware store and pick something up. Or, perhaps I can get rid of the raised bit and then I'd be able to use some sockets I already have to get it out.
Thanks for both of your help!

Edit: Got it open. There are three main things visible: A small control board, a fairly large relay, and the rest is filled with tar. There are some electronics sticking out of the tar, so I am wondering if there is another board under it, or just a few random things. The tar makes it hard to find where things go, but it is giving me a better idea of what things might go to. I'll try to take some pictures of the inside later.

...

Mon Apr 03 2006, 01:21AM

Registered Member #56 Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2445

the transformer I was referring to was the one inside of the supply (assuming it is a 60hz transformer). I am guessing that one is ground, and the other two are hot/neutral (you need separate ground for when you are using 220v, as you get the 220v from connecting to two opposite phased 120v lines)

As to those security screws; all you need to do is put a small screwdriver and give a little twist; the tab pops right off...

Also, upon closer inspection the connector I thought was for all of the interconnects is just a voltage switch, so some pins are probably going to need to be jumped on the output connector to get anything out...

As to the voltage, it quotes 72va and 6ma, which points to 12kv... So either is dissipating 60w, or it will put out considerably more than 6ma or 2kv... Any big heat sinks?

McFluffin

Mon Apr 03 2006, 04:35AM

Registered Member #119 Joined: Fri Feb 10 2006, 06:26AM
Location: USA
Posts: 114

Isn't the VA what goes in and not necessarily what comes out? Perhaps its inefficient and can produce a lower output than what went in. However, there are still a lot of conflicting ratings. Looking at the internal wiring, I wouldn't think that it could handle even 10kV, but maybe wires insulate better than I think they do as I've never really tried pushing their limit.
I'll work on that output. I'd imagine the wires that go to the control board instead of the transformer would be good bets. There is a relay that I'd imagine triggers the primary for the HV part. On the output, there are only 5 of the six taps actually used. Of those wires, inside, 3 are heavy duty and 2 aren't, so theres a good bet that those two are the control wires(guess they aren't common grounded to the HV?). However, I'm a bit confused about why there would be more than two heavy duty wires. Why would there be a lot of power going out more than one?
btw, I saw a YAG laser supply with a similar connector on Sam's laser site, but it didn't really have a good picture, so I'm not sure if its the same. I don't know anything about YAG lasers, so I'm not really sure what to say about that, but I was under the impression they were pulsed, so its probably not quite the same.

...

Mon Apr 03 2006, 04:55AM

Registered Member #56 Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2445

yes the va is what goes in, but if it goes in it mush come out either in the output or as heat so if it is taking 70va in and only 15 is going out it must be dissipating like >50w--thus the 'any large heat sinks' comment.

I think those connectors are pretty much all the same regardless of the laser; that is just what they use.

A yag laser (at least one powered by a 70va supply) will be pulsed, but it is possible that your supply is a capacitor charger for an external bank.

My guess as the the extra heavy duty wire would be that there is a filament that has to be warmed up...

The other two could be signal/return, you could try connecting them and see if you get output; but it is possible that there is 2 states, like a ready/fire.

Is there any indicators on the outside that would give an indication of life when you power it up? Then you could just focus on the output connector and not worry about the input one.

McFluffin

Mon Apr 03 2006, 06:14AM

Registered Member #119 Joined: Fri Feb 10 2006, 06:26AM
Location: USA
Posts: 114

There are some indicator lights on the side:

I think "LASER ON" would probably indicate voltage coming out while "REG" would mean an idle state. I'm assuming if I plug it in and "LASER ON" is on that it won't need to be triggered.
There is a fairly large heat sink mounted to the chasis on two of the semiconductors. You can see it in the back of this picture:

Here is what I've found about the output pins. Pins 2 and 3 are grouned to the chasis. Pin 6 has no connection. Pin 5 goes to pins 1 and 2 of the voltage program plug. I think pin 4 is a thin wire that I can't identify where it goes. Pin 1 seems to be a thick wire and I don't know were it goes either. So really, I am down to four pins.
As far as power it, I think I've figured out the power connections. Pins 1 and 3 seem to go to the transformer and pin 2 is a white wire with a green stripe which is connected to chasis ground. I'm guessing I should put the socket ground to pin 2 and put a 120V wire on the other two pins. Could it make a difference if I use the hot or the other 120V wire to which?
If the voltage is only a few kV, why does the unit warn of 18,000V? I'll try powering it up either in the morning or after school tommarow.

...

Mon Apr 03 2006, 06:52AM

Registered Member #56 Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2445

My guess is that the 18kv is a starting pulse, and 2kv is the run voltage. So when you power it up it put out 2kv, pulse 18kv until it detects a load like the tube fired, then stay at 2kv.

As to the hot/neutral; unless you can trace down any of the pins on the voltage selector connector to go to ground, then it shouldn't matter.

I think the reg led would indicate that the supply is within its tolerances, and regulating... The laser on one should come on when it thinks the tube has fired (or it might just be on whenever the on wire is connected)

Only time will tell what it can put out...

McFluffin

Mon Apr 03 2006, 11:23PM

Registered Member #119 Joined: Fri Feb 10 2006, 06:26AM
Location: USA
Posts: 114

Got a chance to plug it in. I hooked up my variac, slowly moved the voltage up to 120V, and nothing happened. So, I proceeded to check the output on the plug. Pins 4 and 5 had 120V running across them. It turns out there is a low amount of resistance between them(it was either 6 or 16 ohm I think). However, only pin 4 showed to have the equivlent of wall power after further testing. I tried shorting pin 1 to ground, but nothing happened. It has a large wire inside, so I am assuming it is the output and this really shouldn't do anything. I also tried hooking up a laser to it, but that didn't cause the laser to fire up. I also tried shorting pin 5, but that didn't do anything either. Perhaps it needs some sort of logic voltage(like 5 or 12V) to get things going? I do wonder why there is a 120V pin on the output. For cooling fans and such perhaps?

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