After five years of excellent service, our laser tube burnt out last night. This is far FAR longer than its rated life expectancy. A moment of silence, please…
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Luckily @Rob_MacKenzie and @Logan_Buchy had the foresight to buy a spare tube last year and store it at VHS, so I’ll begin replacing the tube immediately today. Not sure when the laser will be fully operational today. Watch this thread.
Here are some photos courtesy of @toma. You can just barely see the fractures in the inner glass tube:
@rsim, @xquared and I spent the afternoon working on the laser cutter, and we have some bad news. We suspect the laser’s power supply also failed when the laser tube burnt out. We’re going to order a new one.
There is also some minor issues regarding the cooling system that resulted from the cleaning and preparation for replacing the tube. As these things go, as soon as you fix one thing, a couple others break.
So I’m sorry to report that the laser could easily be done for a couple weeks while we sort this out.
Has the LCC considered ordering another tube? and perhaps another chiller, and another power supply (on top of the one that was just ordered)?
These components seem to have a limited lifespan and if the laser breaks again in the same manner we’ll probably need to replace the same parts.
If the funds aren’t available would you be able to tell us how much money we’d have to raise to get all the spare parts we need? I have a feeling that we’d be able to raise the money via tilt or something like that.
You shouldn’t need a hv current probe. It should be sufficient to use a multimeter in series with the LV side of the tube and measure the current. This is how I troubled shoot it last time.
A [Mahoney optical power measurement tool] 1 was really valuable. Science World let us borrow theirs last time and it was extremely useful to ensure we were getting the correct power generated in the UV spectrum.
Do we have (or can we get) a schematic for the laser power supply? I have experience repairing switch mode power supplies and high voltage flyback transformer systems (trained in high voltage procedures). Capacitors, power switching MOSFETs and Schottky diodes can often be replaced same day, with locally available direct replacements or equivalents. Some supplies don’t even need parts, just re-soldering joints that have cracked due to high frequency vibrations. Others just need a good cleaning to remove carbonized dirt that acts as a short circuit to high voltages. Of course, extreme caution needs to be taken when handling high voltage systems, as HV capacitors can store a lethal charge, even when the unit is unplugged.
Given the $$ value of the Laser tube and the years of use already put in on the laser it may be better in the long run to put a new power supply in place.
It’s definitely good to have a back up power supply, but if this one can be repaired, we may be able to be up and running sooner. and least i can dream
Given the $$ value of the Laser tube and the years of use already put in on the laser it may be better in the long run to put a new power supply in place.
Certainly, an understandable position on this situation. Just wanted to offer my help if cost or downtime becomes a major issue. Also note that, though new is often better, it isn’t always so. Some new equipment is made with mediocre parts, and actually works better when name brand, or more robust parts get put in. Seen this many times with low ESR caps.
We don’t have a schematic. We did open it and inspect it, tested fuses and the power transistors. We found no obvious issue, but our troubleshooting was far from exhaustive.
