Tube studdering on startup

[Jonathan Bowen]

So I've been fighting issues with this cutter for weeks now. I suddenly lost most of my power earlier today for no reason. I kept slowing the cut down but the cuts kept getting worse. So I ran off to get my other tube that wasn't working right and I've had 2 different tubes in there now and both seem to be doing the same thing. They kinda stutter a bit when it first fires on. Seems to settle down after it warms up. Sorta like a fluorescent bulb will when they get old. Granted I suspect both tubes are bad but could this be caused by the power supply being too high a voltage? I bout a 40/60W power supply in hopes of upgrading eventually. Also of note is the fact that I have lost a lot of current. Like 10 Amps. I'm going to ramp up the input voltage a bit more and see if I can get it to 16ma again. Both tubes had about the same amps. I was testing my connections and just redid both of them before I swapped tubes.

[Dave Sheldrake]

caused by the power supply being too high a voltage?

Could be, if so it can errode the electrodes causing ignition problems in the tubes. Miss-matched PSU's/Tubes can kill one or both items quite quickly.

cheers

Dave

[Jonathan Bowen]

Well hurricane finally said they'd replace my power supply before they admit that the tube is bad. I'm also asking lightobject if it's possible to reduce the output voltage from the power supply. In the mean time... I continue to loss money and get further behind on work. I should just bite the bullet and order the 60 Watt tube.

[Dave Sheldrake]

Current yes on a pot on the underside, voltage no.

cheers

Dave

[Mary Geitz]

I'm having a similar issue with my Epilog. The tube was replaced last year. I warm the laser up for a good 5 minutes before engraving. Mine is in my home office, so it's kept in a warm room. When I send the job, it takes maybe 10-15 passes before it actually engraves. I've tried warming it up longer, but nothing seems to work. I put a file folder on top of the piece until it fires. Then I reset and go again. Anyone else experience this or have any suggestions? I also just replaced both the lens and the mirror.

[Mark Ross]

Mary,

Contact Epilog, they can guide you through how to adjust the tickle voltage and the delay time. You can do it through the front panel.

[David Somers]

Mary,

By any chance is the lid open after you power up but before you attempt your first run? I ask because when I was digging into tickle settings yesterday out of curiousity following a discussion on another thread I noticed that a number of companies do not activate the tickle pulses if the lid is open. Only when it is closed?

Dave

[Mike Null]

David

That would be the safety interlock on all machines and it prevents the laser tube from firing thus no tickle. Most of us bypass the interlocks at some time or other by using extra magnets on the switches.

[David Somers]

Thanks Mike!

I was just thinking that if she was turning it on at the start of a session and had the lid open while she was thinking it was warming up that the interlock was actually preventing that from happening, causing the initial sloooooow startup once she was trying to run a job? In other words, she thought it was warming up but because the lid was open nothing was happening?

I was aware the interlock prevented the tube from firing, but until I had dug a little into the tickle function it hadn't dawned on me the safety interlock would also affect that tickle/warmup function. Then I read her description and thought Hmmmmmm.

Dave

[Dave Sheldrake]

Mary,

RF and DC excited tubes are very different animals from a technical point of view. One uses volts, the other 10's of thousands of volts. The way they work is similar but different enough to mean a lot of different solutions for problems.

cheers

Dave

[Dan Hintz]

Any of the safety interlocks should disable the "fire" signal in its entirety. Since the tickle is, in essence, a very short "fire" pulse, even that is not received.

[Amos De Pasquale]

Does sound like the power supply needs to be eliminated before condemning the tubes, the fact that it stabilizes after warm up is indicative of a faulty electrolytics in the SMPS(Switched Mode Power Supply), do the following only if you are disconnected from the mains; open up the panel until you see the Power Supply for the tube, apply a hair dryer to it for around 3 minutes on high heat, make sure you are moving the dryer around , do not keep it stationary. Once the supply is heated up, close the panel, plug in and check it out, if it runs smoothly, it means your power supply is faulty(the electros inside it getting old). Amos

[Mary Geitz]

Wow - thanks for all the replies. The cover is always closed when I'm warming it up. I'm suffering through a seriously winter in Chicago, and if it's open, the whole house gets cold. I also have it running before I send a job. It only happens the first time I run a job. Even if it sits for a 4-5 hours before running another one, it won't happen again that day. I'm in the habit of covering my substrate until it fires.

[Mary Geitz]

Thanks for all of the responses. When I warm the machine up, the lid is down. The weird thing is that it only happens during the first run. It's fine for the rest of the day, even if there are 4-5 hours in between. The next day, I'm right back where I started. I haven't checked with Epilog simply because I just bought a new honeycomb table and a mirror. This is next on the list.