Medical Argon Lasers???

[perseus]

Hi Adam and all,

I am in Albuquerque, NM. Here is a picture of the PSU. I believe it is an HGM-5 because it seems to match pictures of other HGM-5 PSU's I have found and the control board says HGM and E5-00-07-057 Rev D. There are no other identifying marks I could find. I have made several photos but, as I'm not sure how welcome many large images are on this forum, I have included just two for now called HGM5 Front-Top Marked.JPG and the laser head: ALC-905.JPG

Here are my guesses so far as to what the marked wires and components are:
A - No idea - Appears to go to the power switch in some pictures I have found.
B - No idea - Two separate wires.
C - No idea - Two wires bared & twisted together.
D - No idea
E - Power to cooling fans
F - No idea - Two wires coming from under the control board.
G - One Anode wire & two Cathode wires
H - No idea - appears to be incoming power in another picture I found.
I - No idea - Temperature sensor or light feedback maybe?
J - Is this a series injection transformer for starting the tube?
K - Filament transformer?

I can add more views later if needed. The ALC-905 was from EBay. I don't know if it is any good or not. The only test I have done so far is to briefly put a 15KV neon sign transformer across anode and cathode resulting in a pale bluish glow in the tube.

Any assistance you can offer would be most appreciated and I would be eager to see pictures of your HGM-5 / ALC-903.

Thanks,
Roger

[buffo]

I am in Albuquerque, NM.

Hi Rodger;

Well, you're a bit far to make a road trip to Charleston, SC then! Oh well. I'll do my best to answer your questions here.

Here is a picture of the PSU. I believe it is an HGM-5 because it seems to match pictures of other HGM-5 PSU's I have found and the control board says HGM and E5-00-07-057 Rev D.

You bought this on E-bay from a guy in Wisconsin that goes by "heruursciences", didn't you? It is indeed an HGM5 power supply, and it's identical to the one I have. (Well, mine still has all the dose-related computer circuitry attached, while yours is just the "guts" of the PSU. But they're otherwise the same.)

A - No idea - Appears to go to the power switch in some pictures I have found.

If those two wires run underneath the metal edge on the right and join a wiring bundle that runs on top of the two large blue can-shaped electrolytic capacitors on the bottom of the supply, then yes - that's your 220V power input. (Need at least 20 amps. I plug mine into a 30 amp drier outlet.)

B - No idea - Two separate wires.

This is the power to the relay that used to turn on the main blower that cooled the head. Since you probably don't have this relay *or* this blower anymore, you don't need these wires. Insulate the ends of both wires and tuck them out of the way so they can't get jammed up in anything.

C - No idea - Two wires bared & twisted together.

This is your interlock. The two wires *must* be connected or nothing works. If you want to wire a case intrusion switch, put it in series with these two wires and any time the switch opens, the PSU will shut down. Leave them twisted together for now.

D - No idea

I'm not 100% sure on this, but I *believe* this is used to sense tube current once the tube is lit. You put a voltmeter across the two wires and measure voltage, then multiply by a conversion factor to get tube current. I don't know the conversion factor, and I also do not know if the circuit is properly isolated from the starting pulse. (I think it is, but I'm not sure.) For now, I'd leave this one alone. Later on, you can play with it if you want, but be sure to use a battery powered volt meter, and make sure the tube is lit before you hook it up. (In case the starting pulse isn't isolated from the connector. That HV pulse will fry your meter otherwise!)

E - Power to cooling fans

Yep. 220 volt AC supply to the pair of fans that cool the pass bank. Right on.

F - No idea - Two wires coming from under the control board.

This one is tough. On mine, it runs under the dose control computer circuits and hooks in somewhere. I can't see where though, so I don't know for sure what it does. However, it's just about *got* to be the current control for the tube. That's my guess anyway. More on this below...

G - One Anode wire & two Cathode wires

If you're sure as to which is which, then fine. To check, the two cathode wires come off the top right transformer (labeled "K" on your drawing) on the power supply. They connect to the outside pins (pin 21 and 23) of this transformer, while the anode wire feeds from deep inside the PSU.

H - No idea - appears to be incoming power in another picture I found.

Nope - those are the magnet leads that connect to the head. They should originate from a point below and to the left of the filament transformer that sits on top in your picture.

I - No idea - Temperature sensor or light feedback maybe?

Nope - those go to your igniter. That's the ignition transformer they're coming out of there on top just to the left of the filament transformer.

J - Is this a series injection transformer for starting the tube?

No, it's a big honkin' inductor. I'm not sure exactly what it does.

K - Filament transformer?

Yep. The center tap on this transformer connects to the large inductor (J) above.

The only test I have done so far is to briefly put a 15KV neon sign transformer across anode and cathode resulting in a pale bluish glow in the tube.

That's a good sign that the tube is gas-intact. You should be able to get it working.

I would be eager to see pictures of your HGM-5 / ALC-903.

Here are some pics of my HGM5 back when it still had the original (dead) tube in it. At SELEM 2007 we ripped this dead tube out and connected a 903 tube to the power supply. Scroll down to the bottom of this gallery to see the pics of the transplant. And finally, here's a picture of the hookup as it stands today. (Don't rag on me for the ghetto layout - I'm waiting for the metal cover for the head before I re-wire everything...) Eventually the power supply module will be mounted in the back of the cooling sled that the head sits on.

Anyway, about the mystery wires on the right... I have a partial set of the schematics for this power supply. I'm willing to send you a copy if you think they will help you troubleshoot those wires. Send me your address in a PM and I'll photocopy them and drop them in the mail to you.

As for the 909 tube - I can't help you there. I don't have one, and have never played with one. See if Clandestiny or Mixed Gas can offer some advice about that baby...

Adam

[perseus]

Adam ..... Thanks for all the extremely helpful information. I have mounted all the hardware and I am working on the wiring - using a 40 amp solid state relay to keep my distance from the 230 volts. I will let you know how it goes, maybe even post a picture if I get the laser running.

Roger

[perseus]

Adam ..... I wired my HGM-5 PSU and ALC-905 tube, powered it up and the only action was the cooling fans. The LED's on the control board don't light up and on further testing there was no power on the control or driver boards. I think I am probably missing one (or more) interlocks. Does your HGM-5 PSU have anything connected to the 26 pin connector on the back? The schematics arrived today and have already been very helpful. I assumed the laser used a series injection transformer in the anode line for starting the tube. I made a big toroidal 80:2 transformer for this purpose but the schematic shows the ignition going straight to the body of the tube. Perhaps that explains the tiny ignition transformer I see in your pictures since it does not have to carry the full anode current. With enough study the schematics will probably help me find all the interlocks but I am not there yet. Thanks again for the schematics.

Roger

[buffo]

Does your HGM-5 PSU have anything connected to the 26 pin connector on the back?

Are you referring to the connector on the long side of the PSU, opposite the side with the fans?

If so, then yes, I do have a whole crapload of stuff connected there. All the head electronics (light feedback, fiber launch interlock, etc) connect to that plug via a ribbon cable.

I've still got all that stuff hooked up, though I've bypassed the fiber interlock. The rest of the electronics are just laying there in the space where the original tube used to be mounted. (You can see the blue ribbon cable in the picture I posted earlier that shows the setup I have now.)

I'm in the process of mounting everything into a new enclosure, and I haven't decided what I'm going to do with all that crap. I've heard that there is a simple means of bypassing everything (short a couple pins together on that ribbon connector), but until I'm *positive* it will work, I don't want to mess with it. (It's working now. If I short the wrong pins and blow something up, it won't be working anymore...)

Adam

[perseus]

Hi Adam and all,

Yes - By the "26 pin connector" I do mean the connector on the long side of the PSU opposite the cooling fans. Mine has nothing on that connector at all. I have been communicating with a guy who has a working HGM-5 (PSU and head) without any electronics connected to the 26 pin connector (no control module, control panel or optical feedback). He described the following:

*********************************
The 26 pin connector is just jumpered. Assuming the pins are labeled as:

01 03 05 07 09 11 13 15 17 19 21 23 25
02 04 06 08 10 12 14 16 18 20 22 24 26
............................| |
........................(notch)

then pins 8 and 18 are jumpered, and 10 and 12 lead back into the supply possibly to a small toggle switch located just above the connector.
*********************************

Unfortunately connecting these pins did not work for me. With the help of the schematics I found part of the problem. The solenoids (laser head magnets) are wired in series with part of the power supply. Since my laser head (ALC-905) does not have magnets I just insulated the magnet wires (unconnected) therefore part of the power supply is not getting any power. I think this explains the failure of one of the relays to operate but maybe not the other relay. I don’t know if I can just connect the two magnet wires together or if some load is required between them. If you happen to have an inductance meter I would love to know the inductance and resistance across the solenoids on your laser.

I also noticed that the 6 power transistors across the top of my supply are MJ10005 which are Switchmode Power Darlingtons. I had assumed that the PSU was a linear type. Now I am wondering if it is really a switcher. This makes me a little more optimistic about the possibility of later using it to power the arc lamp in my CW Nd:YAG laser head (the lamp is a QCW166 - 145 volt 20 amp). I understand that the electrical requirements of an arc lamp are similar to those of an Ion laser tube. Does anyone out there have any experience or thoughts on using an Argon laser PSU to power an arc lamp?

Roger

[roSSco]

Lots of great info. in here! I hope to get a medical laser from a friend of a friend soon. He might give it to me! I've gotta call that guy.

[buffo]

Rodger;

I don't have any way to measure the inductance of the magnet - sorry. There's no appreciable DC resistance to the coil, of course.

If I get some time later this week, I'll fire up the beast and try to get some voltage and current measurements on the magnet while it's running. That should give you a starting point.

However, I would guess that you'd be OK just connecting the two leads together. Unless that magnet is also designed specifically to interact with the filament transformer (buck-boost? I can't see how or why it would be that way), it shouldn't matter.

Adam

[perseus]

It Worked!

On the HGM-5 PSU I connected the two magnet wires together (since there is no magnet on the ALC-905 tube. I bypassed the entire interlock string and also connected 12 volts to the LED leading to the 555 timer on the control board. I will post the wiring details tomorrow. At first the tube would not start although flashes in the tube from the igniter were obvious. When I turned R13 [I later learned that tube current is controlled by R2 not R13] on the control board a few turns CCW (guessing this was the right direction to turn up the tube current) it started right away. I was a little worried whether the cooling water flow was adequate so I only ran the laser for about 1 minute at a time. Each time it restarted with no problem. After about 8 times it stopped working and there was no longer any flash in the tube from the igniter. Maybe I got a short in my homemade toroid igniter transformer or I blew something on the igniter board???

For now it appears that an HGM-5 PSU is capable of running an ALC-905 Argon laser tube and that the control module and control panel for the HGM-5 are not neccessary (unless of course that is why my tube stopped working ).

Thanks for the schematics Adam - I would never have got it working without them.

Roger

[perseus]

Update on the HGM-5 power supply and ALC-905 Argon laser head combination.

It is working again (I don’t know why it quit yesterday). The output appears much brighter than my 29mW Argon (with Argon glasses on of course) but I have no way to measure the optical power properly yet. In the unlikely event that the relationship between light intensity and photovoltaic potential of a red LED is linear then it is 4.5 times as bright = 130mW.

Adam and no doubt others have got the HGM-5 PSU with the control module and control panel to work. I had only the basic power supply (no control module or control panel) as shown in my post of 04-19-2008, 21:56.

In case anyone else is trying to get a basic HGM-5 power supply to power a laser head of similar size to the ALC-905 here is what worked for me (referring to the picture of the PSU in the post noted above:

Label A – two wires - 230 volt ac into the PSU.
Label B – two wires – purpose remains unknown. They can be insulated and left unconnected to anything.
Label C – two wires – connect to one another. They are apparently an interlock and may be bypassed by what I did later so they might not matter.
Label D – two wires – Adam suggested these might be the tube current monitor but I have not tested them yet. In any case they do not need to be connected to anything.
Label E – two wires – 230 volt ac power for the cooling fans for the PSU.
Label F – two wires – still no idea what these are for. I insulated them and left them unconnected to anything.
Label G – three wires - One Anode wire & two Cathode wires. The cathode wires are the ones that come from the filament transformer which is Label K. I connected the cathode wires directly to the two cathode wires on the laser tube. I connected the anode wire in series through the secondary of an igniter transformer to the anode of the laser tube. Label I (two wires) are from the igniter board in the power supply. They go to the primary of the igniter transformer. I wound the igniter transformer on a 4 inch (outside diameter) toroid shaped ferrite core. The primary is 3 turns of 10 gauge solid wire. The secondary is made of two 10 gauge solid wires wound together as if they were one wire. There are 80 turns on the secondary. The secondary is wound so that it only covers about ¾ of the circumference of the toroid. The rest of the space was left for the primary with some room on each side of the ends of the secondary because the insulation is not enough for the full ignition voltage that should appear on the secondary. Anyone who knows how to do this properly would probably find my arrangement amusing (but it works).
Label H – two wires – these are the power to the HGM-5 laser tube magnets. Since the ALC-905 tube does not have a magnet I just connected these two wires together – this is necessary to get power to most of the PSU. Adam was right – it does not seem to need a load between these wires.
Label J – At first I optimistically thought this was the trigger transformer. It is actually an inductor. There is no trigger transformer in this power supply – hence my home made toroid.

Not labeled or even shown on the picture is a 26 pin connector on the side of the PSU opposite the cooling fans. Assuming the pins are labeled as follows:

01 03 05 07 09 11 13 15 17 19 21 23 25
02 04 06 08 10 12 14 16 18 20 22 24 26
............................| |
........................(notch)

The information that I obtained earlier to connect pin 8 to pin 18 and pin 10 to pin 12 did not work for me. From the schematics I decided to connect pin16 to 18 and pin 20 to 22. I timidly did this through 100 ohm resistors which are probably not necessary but since it worked I left it alone.

Finally the interlock string was bypassed. There is a solid state relay (SSR) mounted on the big black heatsink that says “Danger High Voltage” in the picture. The SSR is on the side opposite the cooling fans and on the far left as seen in this picture. It has inputs labeled + and -. Connect the negative input of the solid state relay to ground (I used the chassis on the back of the PSU as seen in the picture – NOT the heatsink.)

That is all I had to do to get the PSU and laser head to work. The variable resistor R13 on the control board is said to regulate the tube current but I have not played with that yet.

After my laser has been running for a minute or two the intensity starts to flicker mildly. The flicker seems to come and go randomly. My arrangement does not have optical feedback (yet) although the power supply does have this capability built into the control board. Maybe optical feedback would resolve the flicker???

One more thing – the schematic shows a chip (AM6301) on the control board (mine actually has a TDA4700 instead). These chips are switching power supply regulators. It seems the HGM-5 really is a switching type and not a linear (but I’m not ready to risk my oscilloscope to find out for sure).

I hope this information is useful to some other hobbyist who gets his hands on an HGM-5 PSU.

Roger