LaserUser.com Forum (formerly RDWorksLab)

First off, how does this damn connector come apart ????
Second, does anybody know the value for the soldered in fuse in a MYJG80R PSU ?

I answered my first question. Found a picture of the two halves. It was just tight enough to need two pairs of pliers to crack loose. Got the fuse off the board, and it looks like 4A, but the inscribed print on the fuse is a bit light. Can anybody verify that number?

Okay, so now I'm really confused. I would have had to drive over an hour to get a solder in 4A slow blow fuse. I have some of the push and twist holders from other equipment, and the hardware store had regular slow blow fuses, so I opened up one of the holes in the end of the PSU and mounted the new fuse holder.

Everything was great for a few hours, then I popped the 4A slow blow. I let it sit for a bit, popped another 4A in and finished the job.

But it was gnawing at me. Do I have a PSU problem, or just happened to get a weak fuse?

So I pulled and taped the internal power feed, and wired a cord via one of the back convenience outlets so I cold plug in my Kill-=A-Watt and check current in real time.

Here's where it gets weird. I have a 4A slow blow fuse in, and I cut a few 50mm squares ans circles to see what it pulled at max power... and the Kill-A-Watt shows 5.4A... WTF ???

I do remember going through things with the whole thing plugged into the Kill-A-Watt back when I got it, but I can't for the life of me remember what the jump was when the laser PSU was firing the tube.

Does anybody know what a MYJG80R actually draws under power?

Dave I found this on amazon
I think you have issues, maybe with the power supply. When I’m running my 75 watt machine full bore with the water & air pumps and the fume extractor I’m drawing around 5 amps for everything. So if you are popping a 4 amp fuse something is up.

Do you have any arcing on any of the wires to the tube?

I found the same listing, it doesn't list the incoming AC draw.

No problems other than popping fuses. The laser is right at two years old. I mounted the twist in fuse holder and worked for an hour or so and then it popped. Weird thing is I found my notes from when I first got the machine. With all the warning I plugged it into my Kill-A-Watt and checked the real time current draw. Back then I had a note that said it was drawing a little over 6A, but there may have been some stepper power in there as well. Cloudray did get back to me and says it should be drawing 4A. I have a feeling the laser PSU is on it's way out, but I have to limp it along until I have the funds to replace it. Going to add a little fan blowing directly on it and see if that helps. It's not hot where the laser sits, but come summer it's not exactly a conditioned space 100% of the time.

Dave

The first picture has the specs. in it. Input power is 3 amps max.

I see online fly back transformers (high voltage) for sale for these power supplies. I’m guessing that is what fails in them. If the windings start shorting out it will draw more current. Once they start shorting it will get worse.

My 80 PSU has two of these in series that looks like this.
Hope this helps.

That's what's in mine. I'm just hoping to limp it along for a while... cross your fingers.