Omnichrome

I just unboxed my Omnichrome series 74 laser with 2 power supplies and all cords, I got this setup on ebay for 120.00 shipped. The tube is gone though, broken. I know this was a deal that could have been a lot better, I knew the tube was broken, just not shattered. I need to test the power supplies, I was told 1 worked. I am getting into these lasers too much!

Slow down mate - soon you will have more lasers than I do (actually that wouldnt be hard, I only have 3)

Well I told my wife, now I have an X-large, large, medium and a handful of smalls. All thats left is the several in between each of them. I am actually about done for the big lasers, I was looking at a pulse nitrogen laser. I definatly am doing a home built Co2, not sure if it will be 40 or 80 watt though. I am talking with the local power company to get a substation put in on the back of my property.

wby300 said:

I just unboxed my Omnichrome series 74 laser with 2 power supplies and all cords, I got this setup on ebay for 120.00 shipped. The tube is gone though, broken. I know this was a deal that could have been a lot better, I knew the tube was broken, just not shattered. I need to test the power supplies, I was told 1 worked. I am getting into these lasers too much!

Click to expand...

be careful with the broken tube.

the beryllium oxide dust is very toxic.

Yep, have not touched it yet. I am going to remove the top to see if the glass can just be dumped out of it.

wby300 said:

Yep, have not touched it yet. I am going to remove the top to see if the glass can just be dumped out of it.

Click to expand...

BeO is not in a 74 series HeCad. Hexavalent cadmium is in the 74.

Dont lick, dissolve, eat, or touch the Cadmium* and you'll be fine.

Getting it in your bloodstream could shorten your life and cause you to have four headed children.

For a home owner, its legal trash.

It is single isotopic cadmium to get the gain up. The stuff costs a fortune when new. It is not radioactive.

* It takes a prolonged daily exposure to mess you up, unless you ingest it.
This was learned the hard way as refridgerator parts were plated with Cadmium for decades.

The ceramic wool insulation around the tube can make you itch, for a few days if it gets rubbed into your skin.

If you ever find a gas intact 74 head, let me know here or on PL and I'll send you a copy of the instructions for matching a head to a PSU.

Steve

Cool, I have a line on some more heads, plan to get 2 for the power supplies I have then use this broken one for parts. I tested the power supplies and 1 works but the other does not, will open it up and see, no external fuse so it may be just a popped internal fuse. Both are the model 100, is there a reason why they both have a factory printed B on the right side front just above the Omnichrome name?

wby300 said:

Cool, I have a line on some more heads, plan to get 2 for the power supplies I have then use this broken one for parts. I tested the power supplies and 1 works but the other does not, will open it up and see, no external fuse so it may be just a popped internal fuse. Both are the model 100, is there a reason why they both have a factory printed B on the right side front just above the Omnichrome name?

Click to expand...

THOU SHALT NOT HOOK UP A 100 WITHOUT A GAS INTACT HEAD ATTACHED>
IT CAN/WILL KILL THE HECAD PSU.

You cannot "TEST" the psu without a working head. A arc will kill it. Operating unloaded (no plasma) will kill it.

IF the PSU causes Arcs inside the head at the connector, the PSU is fine, and the tube is shot. Shut down right away. The arcing WILL kill the psu in a matter of seconds.

B means its modified for SLA (Stereolithography) service, as well as other things. You will not see the difference, except it can be hard to get it to go into shutdown.

Note, there are pots on the side of the head that have to be adjusted to match a head to a PSU, when you get a head that lights, let me or Dr Sam at the FAQ know and we'll try to get you a PDF of the manual.

Use the shutdown cycle on the PSU if your get a working head. let it run a few minutes, and then shut it down until you get the matching done.
DO NOT JUST TURN THE PSU OFF once the tube is lit. This can really kill the tube fast.

Hecad heads either work or they dont, there is no practical tube swapping, the optics are sealed to the tube, and there is a sticker on the side of the head with the factory tuning. If you do not set the potentiometers to match the head to the PSU, it can gulp cadmium (bad) or fill the tube with extra helium, which is really bad.

I do not advise people to buy EBAY HeCad heads. Most come from machines that use every last hour on the head, and then they get pulled. Tubes are 7,000$ from the factory, so its not much more to buy the head, so dead heads are all over the place.

Also watch out for lasers at 325 nm UV, you cannot convert them to blue.

Please dont waste your money, buy whole systems that are known to work.

These are not "Fixable" like argons are. If I had to guess the ratio, over the years, of people who got working heads its like 1 in every 10 auctions a working head might slip out.

I know, I bought 4 of them learning. 1 worked well, and it was a system,known to work, not from a auction.

I've also spend hours at a laser enthusiasts meeting trying to tune 4 heads to get one to lase. Some times they will light, and just be Cadmium depleted. No matter what I did, those would not lase. I have ways of checking if cavities are aligned, and those were aligned. No matter what we adjusted, they just would not come into mode. Four very skilled laser engineers wasted most of day trying. Its the nature of the beast.

DO NOT HIT REMELT, just dont. Its really for when the Cadmium blocks the bore, which is rare.

Steve

Thanks for the info, I was looking a kimmon on the same spectrum, are they a better choice? Then I would have to get psu for it though too.

wby300 said:

Thanks for the info, I was looking a kimmon on the same spectrum, are they a better choice? Then I would have to get psu for it though too.

Click to expand...

Kimmon is worse for intra-unit compatability. They do not show up much. They make a nicer head, but the psus are difficult. You really, really, need to buy a whole working system that is lasing, before you spend your money. Dont even think about buying a Liconix, that company has been dead for 15 years. Ebay recyclers have no clue, and just because it is gas/glass intact when you buy them, does not mean it has a chance of working.

I have a friend who went through 6 74 series heads before he got a working one, and that is only when I chanced upon a working, complete system. I've went through 4 of them before I got one, and have not found another since.

I've been using/tuning HeCads of both wavelength s since 2005, they just are not mix and match.

Steve

LSRFAQ said:

Kimmon is worse for intra-unit compatability. They do not show up much. They make a nicer head, but the psus are difficult. You really, really, need to buy a whole working system that is lasing, before you spend your money. Dont even think about buying a Liconix, that company has been dead for 15 years. Ebay recyclers have no clue, and just because it is gas/glass intact when you buy them, does not mean it has a chance of working.

I have a friend who went through 6 74 series heads before he got a working one, and that is only when I chanced upon a working, complete system. I've went through 4 of them before I got one, and have not found another since.

I've been using/tuning HeCads of both wavelength s since 2005, they just are not mix and match.

Steve

Click to expand...

HeCd = The expensive holy grail :cryyy:




Peace,
dave

It killed me that I didn't have the money to throw around at the time, but a few weeks ago a working HeCd came up on fleebay with PSU and real pictures of it running(key).....it went for a whole $300.:cryyy::cryyy:

Dave, do yourself a favor and do not sniff the white lagging material on the tube in that picture, nor leave dust from the lagging material laying around. If the lagging seriously cracks, spray with a water mist and bag, then dispose of in normal trash. Some of it is harmless and alumina based, others (older) are asbestos. No way to tell.

Its not that harmful because the fibers are contained in a binder, but one prefers to know.

Steve

LSRFAQ said:

Dave, do yourself a favor and do not sniff the white lagging material on the tube in that picture, nor leave dust from the lagging material laying around. If the lagging seriously cracks, spray with a water mist and bag, then dispose of in normal trash. Some of it is harmless and alumina based, others (older) are asbestos. No way to tell.

Its not that harmful because the fibers are contained in a binder, but one prefers to know.

Steve

Click to expand...

Thanks for the reminder, Steve.

I had a scare a few years ago with a shadow on my lung X-ray that was surrounded by radiating striations.

Thankfully it ended up just being some old scarring from an infection.

However, that was enough to scare me into diligence about friable asbestos.

Peace,
dave

It's difficult to find a working Omnichrome Series 74, at least on eBay anyway. Good thing is that they are pretty tough from my experience. I shipped one up and down the country twice and it survived hassle free.

You really need a head that matches the PSU too.

And listen to Steve, don't hit the remelt button.

I havent hit any buttons, I did actually remove the head from the housing. There was a lot of contacts to cut to get it out of there, I am actually considering getting a Kimmon and just selling the 2 power supplies I got with this laser.