Melles Griot 05-LPL-340 DEAD?

I have an old Melles Griot 05-LPL-340 power supply for my 4mW HeNe that seems to have quit. I haven't used it in maybe a year or two and the green light goes on but that's about it. I don't think that there's any power to the Alden plug because I could unplug the head and use it as a high-voltage capacitor for a short period of time. From some research I did, most likely the output caps in the supply have dried up.

I opened up the box to find...a smaller, dark-green box with some glue on the bottom. Are these supplies potted? If so, then I guess I'm stuck using the box for the new power supply from eBay or elsewhere. If it's just glued down, I will remove it and do some testing.

The head is a 05-LHP-141 from '87 in case that matters.

Some pics.. would be great :beer:

the daguin machine needs to see this thread LOL

personally i know little about gas lasers but IIRC these psu's can go bad pretty easily

as far as i know these tubes don't crap out easily

good luck i love seeing gas lasers

Here's a trick you can do to check if the PSU is working.


First make sure the plug for the laser is fully inserted into the PSU, then turn the PSU on for 30 seconds.

Next, turn off the PSU, then carefully pull the laser plug from the PSU, then touch the 2 metal points on the plug to a metal object. If you see a spark, the PSU is probably working. If no spark its probably dead.

Solonar said:

Here's a trick you can do to check if the PSU is working.


First make sure the plug for the laser is fully inserted into the PSU, then turn the PSU on for 30 seconds.

Next, turn off the PSU, then carefully pull the laser plug from the PSU, then touch the 2 metal points on the plug to a metal object. If you see a spark, the PSU is probably working. If no spark its probably dead.

Click to expand...

Ironically, that's what I tried and nothing. I also used to hear a light 'tick' noise after the delay period was over, and that's gone too.

If nothing else, I'll wait a day or two and just remove the dark green box. If it's dead anyway, there's no harm finding out whether it is potted or not.

Regarding the earlier posts, once I get it working again I should be able to post a pic or two.

You said you could unplug the head and use it as a HV cap. Does that mean it appeared charged?

As with most things Melles Griot, it probably is potted inside. I'm not totally convinced that it's dead; though your tube could be having an issue.

aryntha said:

You said you could unplug the head and use it as a HV cap. Does that mean it appeared charged?

As with most things Melles Griot, it probably is potted inside. I'm not totally convinced that it's dead; though your tube could be having an issue.

Click to expand...

Yes, back when it worked, I could use the laser head as an HV cap. It's not a big shock, but something to watch out for lol.

I'll take it apart tonight then and find out if the supply is potted in.

I found that the power supply's box inside isn't really glued in much and is more or less press-fit in there. The actual number on it is a 05-LPM-340-3 (4-7mA @ 1.3->2.6kV) and according to Sam's FAQ I found here, it is potted:
Sam's Laser FAQ - Complete HeNe Laser Power Supply Schematics

So...considering how much work it would be to remove the potting compound and not actually damage anything, I'm probably better off finding a replacement somewhere. Too bad it's potted, as someone even came up with a schematic for it--making that an easily fixed item (if it's only caps or a transistor for example.)

I'll do a little more surfing these next few days, but if anyone has a suggestion for this PSU let me know.

Thanks.

-ADDED- P.S. Not much on eBay right now. I found this however which is the closest match for around $150. It should be an easy retrofit in my current box (it's much smaller):
http://www.mi-lasers.com/hene-laser...hene-laser-power-supply-for-9-to-16-heads-p-6

I received the Voltex DG-22 today and "hot wired" the laser quickly; it works. This supply is also potted. (And smaller than the original by quite a bit!)

Once I get the bench supply rewired and assembled I'll post a pic here once I figure that out.

It's been almost a year since this last post? I'm such a slacker.

Anyway, to the four people who were reading this thread, in case you're still around the HeNe does work. I plug it in every so often to charge up the caps and warm things up a bit.

I tried taking a pic of the beam so I could post it, but these low mW lasers look pretty weak compared to the 1+W 445's or 100mW+ greens. I don't think anyone would be too excited about seeing a few particles of dust briefly turn red. These gas lasers are pretty much for nostalgia purposes now that you can get diodes with a lot more power. (Speaking of the visible range; not 1kW CO2.)

Thanks to all above.

Krusher said:

It's been almost a year since this last post? I'm such a slacker.

Anyway, to the four people who were reading this thread, in case you're still around the HeNe does work. I plug it in every so often to charge up the caps and warm things up a bit.

I tried taking a pic of the beam so I could post it, but these low mW lasers look pretty weak compared to the 1+W 445's or 100mW+ greens. I don't think anyone would be too excited about seeing a few particles of dust briefly turn red. These gas lasers are pretty much for nostalgia purposes now that you can get diodes with a lot more power. (Speaking of the visible range; not 1kW CO2.)

Thanks to all above.

Click to expand...

:cryyy: I am sorry for your loss... :cryyy:

Jim

LOL.

The HeNe works fine and still has some good uses. I might get into holograms someday or need a beam with only .8mrad divergence. Also, you can run a HeNe for years if needed while these high power diodes only have a MTBF of 8-10,000 hours.

They're just not for show anymore when you can get a laser pointer from the store with more power. Still, something cool about them makes it worth hanging onto vs. listing on eBay.