411 Full power without motion

[johnballard]

Hello,

I won a Lagun 250 4000lb milling machine in a silent auction. Having moved it 35 miles and then into my garage, I cannot get any axis to move. "Full power with no motion" or "Stall...".

I have no experience with milling machine software or hardware so I am hoping someone can help me. Here's what I have already performed.
1. Verified that there is >2Mohm between servo drives (+/-) and ground (x, y, z)
2. Verified all fuses are good.
3. After powering up, spindle drive works both directions from the pendant.
4. My PC indicates that HOME is not set. I follow instructions and press Cycle Start and within 2 seconds I get the fault.
5. I verified that drives are free. I can run all three ball screws by hand.
6. In order to get the spindle to work again, I have to hit e-stop and then reset it.

I do have an electronics background but I need a little help to get started. What should I check for now?

I looked through the report.txt file and I see that this error has occurred since the machine was retrofitted six years ago. Somehow I think the milling machine was auctioned off because nobody could get it going. Mechanically it seems to be in great shape. There is no rust. Opening the electrical cabinet is a different story - what a mess. I saw three 10AWG wires had been cut off so I traced them back and they had been cut off on BOTH ends so the shards of retrofit were never cleaned out:-(

[cncsnw]

Most likely, you are not getting DC power to the VM+ and VM- terminals of the All-in-one DC unit.

Somewhere in the cabinet there should be a rectifier to make ca. 100-160 VDC out of 70-120 VAC, depending on what transformers (if any) are available and were used. The minus side of that DC supply typically runs directly to the VM- terminal of the All-in-one DC unit. The plus side typically runs through the emergency stop contactor, then to the VM+ terminal of the All-in-one unit.

Common reasons for failing to get VM+ to the All-in-one unit are that the emergency stop contactor coil power circuit is not wired correctly, so that the contactor does not close when you release emergency stop; or that the contactor has burnt contacts, so that power does not get through it even when it is closed.

Can you identify your servo power rectifier? Can you identify your emergency stop contactor? Does the emergency stop contactor click open and closed when you press and release the emergency stop button?

Post a picture of the cabinet, even if it is a mess.

[martyscncgarage]

Hi John, you may be correct. A conversion was attempted but someone did not understand what might the issues have been.
Can you take pictures of the control cabinet, the servo motors and their lables, and of the machine, the PC?

Along what Marc suggeested, you might start with the All in One DC installation guide and its associated schematic most pertinent to your machine and start at square one and work your way though it. Not sure if you have a variable frequency drive or contactors controlling the spindle motor. That's why I'm suggesting you provide photos of what you got, the make model of the servos etc.

All in One DC installation manual: https://www.centroidcnc.com/downloads/c ... manual.pdf
Centroid Mill Operator's Manual: https://www.centroidcnc.com/downloads/c ... manual.pdf

Use this post as a guide. More information we can help you better: viewtopic.php?f=64&t=383
I created a series on the All in One DC installation that might help along with your manual.

Marty

[johnballard]

Awesome responses!! I'll get home late tonight so will not be able to post any additional info tonight. BTW I might have all the time in the world next week as we are being forced to work from home (COVID-19). Stay tuned. Again thanks for the quick feedback.

[johnballard]

I was able to take some pictures. I could only upload 10.

The PC is a DELL running Windows 7. I have updated all the windows updates. There does not seems to be any issues there. The lights on the AllIn1DC come on when the PC / USB has booted, so they seem to be communicating.

I have a rotary phase generator since the power to my house is only 230vac / 2 phase (@180). The controls transformer is connected to my original phases, not the generated phase. The spindle contactors just reverse a phase. The milling machine has mechanical spindle speed control. I have re-wired all the 3-phase motors for 230vac (originally 460vac). That includes the spindle, the knee, and the coolant pump. The controls transformer was also re-wired for the lower incoming voltage.

The automatic draw bar works ok. The pendant and MPG seem to work fine, since the pc recognizes when they are not attached. Since the lube pumps turns on with axis motion, I'm not sure if they work.

I have not tested any limit switches. I did read at some point you could use the screen to show the state of all inputs, but I couldn't seem to navigate to anything that would show inputs. I could get to status of the AllIn1dc, but since I am not familiar with any parameter, it didn't mean much to me. Looked benign.

I will investigate with power tomorrow.

John

[martyscncgarage]

OK. It does look like someone started the conversion.
I would unbelt all the motors from the screws first.
Did the machine have a schematic? Attached is one for a spindle with contactors FOR REFERENCE.
I would start with the All in One DC Installation guide, start from the beginning and work your way through it STEP by STEP.
Someone had to remove the tachometers from those DC Brush Servos and install encoders. IF you follow the step by step guide you will be able to find out how many line encoders were put on the motors.

We'll be here to help, but start at the beginning of that manual and work your way through it. When you get stuck tell us where you are in the manual and post here.

I would put a volt meter on that big blue capacitor's terminals and check for DC voltage there first with the cabinet powered on and see what/IF you get. IF it has power, it appears that the control was wired for direct rectification. About 170VDC is what I would expect.

Marty

[martyscncgarage]

The other thing of concern, is whether or not those particular Baldor motors can take 170VDC. The one lable you took a picture of does not show MAX VDC.
Do the other motors show anything on their lables?
Marc may know, otherwise you might have to check with Baldor. They might, because I don't see any place for the step down transformer, and the blue filter capacitor and bridges were on a chassis that apparently held the original Glentek drives.

[martyscncgarage]

The reason I tell you to take the belts off the motors, is there is always a chance a servo might try and run away before the control can shut it down. Also, very important you follow that installtion guide to the "T". If you handle the pulleys at any time, at least use a gloved hand and USE CARE.
If you follow the install guide you should be fine. I had one of my motors holding UNTIL it was commanded to move and it took off. Turned out the polarity of the motor was wrong. Essentially what was happening, is the control is holding the motor, but when it is commanded to move the control applies voltage to the motor, the motor turns one direction but the feedback from the encoder tells the control its is going the wrong way, control applies more voltage to try and get it back into position, the two get further and further apart. Just be aware of this. You MAY or MAY NOT encounter it.

Marty

[cncsnw]

If this data is applicable to a motor built in 1997, then the nameplate voltage is 150 VDC.
https://www.baldor.com/catalog/MTE-4070-BLBCE

Second the advice to check the DC voltage across the big blue capacitor. If you don't have power suitable for running the motors there, then you won't get it at the drive, and the motors won't move.

If you have good DC voltage at the capacitor (say, 100 - 160 VDC), then watch the E-stop contactor (2CR?) when you release emergency stop. Does it click and pull in? If so, do you then measure good DC voltage at the VM+ and VM- terminals of the All-in-one DC unit?

[cncsnw]

To see the state of the PLC inputs and outputs, press Alt-i at the main screen (the main screen is the one that says "Machine home not set" and has the F1/Setup and F3/MDI keys on it).

The inputs are the first 16 dots on the top row. Green = 1 = closed, Red = 0 = open. The outputs are the first 9 dots on the second row. Green = 1 = on, Red = 0 = off.

Press Alt-i again to dismiss the PLC display.