Restoring a Mini 24

[Dan Wilhelm]

What material are Epilog lenses made of? I've never heard of a lens 'burning.' Usually, IR lens material is fairly heat resistant and the worst that could happen is thermal stress fractures.

[Dan Hintz]

What material are Epilog lenses made of? I've never heard of a lens 'burning.' Usually, IR lens material is fairly heat resistant and the worst that could happen is thermal stress fractures.

Zinc Selenide, same as all of the other lenses in these machines... by "burned", I simply mean you've cooked the AR coating and/or thermally stressed the lens. They're cheap, I'd buy a replacement to have on hand anyway, so use the old one until you can determine it's truly junk.

[Dan Wilhelm]

Gallium Arsenide also works as an IR lens. I wouldn't say they are "cheap," especially from Epilog. That was my plan anyway. I was going to fire the laser up with the old lens in, and if I only had focus/power problems, then I would change the old lens out for the new one.

[Dan Wilhelm]

Got everything installed, and tried my first power-up today. The laser cooling fans powered up, but nothing really happened. The control panel display shows about half solid rectangles and nothing else. The green light on the power supply and all four red lights on the main control board indicating that the voltage rails are OK are lit up. The bottom light next to the RJ-11 cable on the laser is lit green and the top light is lit red. There is a button on the control board, and when I hold it down for a few seconds, an amber LED lights up for a couple of seconds, then a green LED flashes twice. None of the buttons on the control panel change anything.

When I powered up the laser before tearing into it, the Z and Y axes homed, but an error was displayed on the control panel because the X-axis couldn't move (melted belt). I seem to have taken a step in the wrong direction. Any suggestions?

[Dan Wilhelm]

After some troubleshooting with Epilog tech support, they say that the control board is bad. All of the power rails are energized, but there is no "boot up beep." I must have done something during cleaning or re-assembly because the board was working before I took everything off. The only thing I can think of that might have killed it is when I was moving the X- and Y- axes around after putting them back together, I saw the voltage rail lights on the control board light up. Apparently, the servo motors act as generators when you move them manually and will feed voltage back to the control board. It's plausible that this voltage fed back onto the 1.5 or 2.3V rails and fried a chip. Kinda bad design if you ask me. It would be trivial to put diodes or opto-couplers on the control board to prevent back feed voltage from the motors.

Anyway, new control board on the way and fingers crossed.

[Dan Hintz]

The only thing I can think of that might have killed it is when I was moving the X- and Y- axes around after putting them back together, I saw the voltage rail lights on the control board light up. Apparently, the servo motors act as generators when you move them manually and will feed voltage back to the control board. It's plausible that this voltage fed back onto the 1.5 or 2.3V rails and fried a chip. Kinda bad design if you ask me. It would be trivial to put diodes or opto-couplers on the control board to prevent back feed voltage from the motors.

It's possible you were back-powering the LEDS through the body diodes, but it shouldn't pose a problem... something else toasted the board.

[Kevin Gregerson]

After some troubleshooting with Epilog tech support, they say that the control board is bad. All of the power rails are energized, but there is no "boot up beep." I must have done something during cleaning or re-assembly because the board was working before I took everything off. The only thing I can think of that might have killed it is when I was moving the X- and Y- axes around after putting them back together, I saw the voltage rail lights on the control board light up. Apparently, the servo motors act as generators when you move them manually and will feed voltage back to the control board. It's plausible that this voltage fed back onto the 1.5 or 2.3V rails and fried a chip. Kinda bad design if you ask me. It would be trivial to put diodes or opto-couplers on the control board to prevent back feed voltage from the motors.

Anyway, new control board on the way and fingers crossed.

Double check your connections and sensors to make sure you don't have any bad grounds or shorts while you are at it.

[Dan Wilhelm]

Got the new board today, installed it, and everything seems to be working. I haven't yet fire the laser, but the red dot pointer works fine. The motors sound like they are running a bit rough, but that may just be from not moving for 6+months.

Can anybody send me a picture of an intact rotary attachment plug in the back of their cutting table? Epilog has tried twice to send me the Molex for that connection (mine melted in the fire), but they have sent me two different incorrect connectors. I'm pretty sure its a standard Molex, so I was just going to buy one from DigiKey or something. Problem is, I don't know exactly what the correct intact one looks like.

[Dan Wilhelm]

Well, hit a milestone today. I successfully fired the laser. The power output is low which I'm hoping I can fix by putting the new lens assembly in. However, I can't really test anything until I get the exhaust situation fixed.

I realized that I don't have the duct adapter for this laser. I tried taking the one off my GWeike, which would probably work, but the mounting hole pattern doesn't match. I bodged it on just for testing purposes, then the crappy exhaust fan motor included with the GWeike crapped out on me. I ended up running the test just using a vacuum for smoke removal (light engraving on plywood...didn't even make it through a ply).

Is there a standard size for the duct adapter on an Epilog, or do I need to order that part from them? I don't mind the expense...just don't want to bother them unless necessary. As for replacing the exhaust fan, I've been reading up on here, and the Harbor Freight dust collectors seem to be the low-end standard. I see they run about 60 dB for noise, but I don't know how that compares to the noise of the laser itself (which I consider pretty loud).

[Dan Wilhelm]

Did my first paying job on the Epilog today (three nameplates on LaserMax). I screwed up five of them before I got three good ones. I did all of my testing to get the power levels right in the back left corner of the cutting bed, and everything was working fine. When I went to make the 2" x 8" nameplates, the engraving was a lot lighter towards the right, and it didn't cut all the way through like it did during testing. After screwing up the original 3, I went through and leveled the x-axis to the cutting bed.

I started a new batch to the right of the first 3, and it still wasn't engraving deep enough. I hit the stop button halfway through the 2nd one and that's when I noticed the problem. I had the red dot pointer on, and saw the red dot on the wall next to the laser (still don't have the side panels back on yet). I adjusted the 2nd mirror down a little bit, restarted the job, and it worked like a champ. I got 1 usable nameplate out of that second batch, then had to reprint the first 2. I tried engraving over the second screw-up by just restarting the job, but apparently I bumped the material during the adjustment process because the engraving was off by about 1 mm.

Anyway, I'm now confident that everything is operational and properly aligned. The best news is that I did the whole job with the old lens and final mirror. I'm still going to keep the new one I bought just so I have a spare. If anybody is interested, I can post some before and after pictures of the restoration.

[Ed Maloney]

Pictures would b e great.