Problem- Smoke a G540 Today

[Bob La Londe]

Ok, I've got the Taig running pretty good. I've run code files over a million lines now with satisfactory results.

I decided it was time to see why I couldn't seem to get good consistent results out of the Max NC. Except for lead screws they are functionally the same.

Taig
G540
382 oz single shaft motors from Ahren.
3.56 resistors installed by Ahren
48V DC unregulated power supply
1/2 20 screws 40K steps per inch

2 gig computer
XP Pro Roll Back

Max NC
G540
380 oz dual shaft motors from Keling
3.48 resistors installed by me
48V DC unregulated power supply
1/4 16 screws 32K steps per inch

3 gig computer
XP Pro Rollback

I figured they should run roughly the same, but the motors on the MaxNC were noticeabley weaker and stalled at lower max speed. It drove me nuts, and I was never able to trust the machine to do a good job.

I decided to start checking things today. I found the power supply was only putting out 40/41 volts with voltage pot cranked all the way to max. I happen to have another one so I figured I would swap it out. When I pulled the PS I noticed the 115/230 slider was at 230 instead of 115. I slid it back to 115 and plugged it in with no load and adjusted the pot to 48VDC. I powered it down hooked everything back up and proceeded to jog the motors to see what would happen. It seemed to work just fine, but the motors were still able to be stalled much easier than the motors on the Taig. I was just running the Z up and down when I heard a pop from the G540 and turned to see a whisp of smoke come out.

I powered everything down. Checked all my connections, double checked the connectors, resistors, etc, and powered it back up. I ran the X back and forth a couple times and SNAP!, and another puff of smoke. It is dead. I did open it up and found a couple ICs melted on one of the circuit boards.

I do have another G540 and another 48VDC power supply, but I am afraid to hook them up. Everything seems to be hooked up right. The PS was reading 50VDC before I shut it down. The G540 is rated to 50VDC, and Marcus told me everything they build has a little safety margin.

The tough thing is I am at that point where I need another working machine, but I can't quite afford to buy most folks turn key machines.

[Bob La Londe]

Anyway, I can't see any reason that the G540 should have smoked. The only real change was that the power supply was putting out the 48-50 volts it should have been all along. It had been hooked up and used for tiny jobs for several months the way it was.

[nickswimsfast]

This is just an educated guess, but I'd say that switching the PS to 230 causes the transformer to function at a different ratio. 230v : 48 vdc compared to 120 : vdc. This might have changed the current. Id venture a guess that was why. I'd verify with someone who knows more about electrical than me.

[Al_The_Man]

I tend to agree.
With a linear unregulated supply you should have been running at low/under voltage using 120v on the 240v input?
If you were getting 40v with it set 230v with 120v supply input, a linear supply is a direct ratio, so setting it to 115 I would expect double the output? Is this a toroidal linear supply?
Although if you have an adjustment pot, it cannot be simple unregulated linear?
Al.

[Bob La Londe]

Well, I guess I am going to have to risk my spare G540, but I will use the spare power supply with it. I think I am going to eliminate the DB9 patch cables and make up my own cables as well. Maybe using the EZ-G540 connectors.

I still do not see why the G540 would have smoked. Voltage was in spec. Resistors read ok on pins 1-5. Yeah, its not a simple unregulated power supply.

Power supplies are the same model on both machines.

Motors are simple 4 wire motors.

[Bob La Londe]

Well I shipped the controller to GD, and I got it back unrepaired and with no real diagnosis either. They said I might have hit it directly with AC or something. I didn't so now I have a machine sitting and I am afraid to hook it up.

Not sure if I had a bad controller or what.

Like I said before. I was doing a test cycle just running the motors back and forth with no cutting load when the drivers smoked.

[Bob La Londe]

I hooked another G540 I had to the same power supply, motors, cables, etc and ran it for a little while (couple hours) with no problems.

I guess I am just out one controller.

[Mariss Freimanis]

You aren't "out one controller". Return the G540 to us and we will repair it for free (if it's repairable) including free return shipping. We'll also let you know what got done to it to make it smoke. My guess?; the G540 smokes if you apply more than 68VDC to it. It carries a tell-tale over-voltage detect "fuse" that blows if voltage exceeds 68VDC.

A good rule is to never monkey with power supply switch settings while the supply is attached to a load. Disconnect the load (G540), change settings and measure the resulting voltage before reconnecting it to the load.

Mariss

[Bob La Londe]

I already sent it back once, and received it back with nothing done. But thanks anyway. I was told 3 of the 4 stepper drivers were fried and there was some damage was done to the main board. Your people sent it back. I figured I'ld keep it for the one good stepper driver if I ever need it for anything.

Its probably out of warranty by now anyway.

The big Hurco mill is coming along slowly. Probably going to go with the Viper 200s or the DuGongs. I've already picked up a smooth stepper and one of Arturos break out boards for my interface. I seriously considered the G320X, but decided your "safety margin" in design wasn't enough to make me comfortable since I really want to run a 90V power supply to the servos.

I've got two more projects I am working on besides. An RF 30 and an 8x18 lathe. I am seriously considering CNCing the 8x18 but I don't know how I want to control that one yet. The RF30 may get left as a manual machine for those little bits of work.

Anyway. I appreciate the thought.