Acu-Rite Millpwr Gen 1 Servo Drive Error

I have a Gen 1 Millpwr, 2-1/2 axis Mill controller. Has worked well for many years. Initially when I turned the machine on, nothing would show on the monitor, though it had all of the correct beeps, while loading. I tried multiple things and I believe that after cleaning the contacts on the "scuzzy" cable(?), between the box and monitor, I was able to get the DRO portion of the program to show on the screen. Now, All axis read and work as they should. The program loads, all of the beeps are correct, but when you attempt to home the machine, it will instantly kick out a servo drive error. (table is free, moves easily etc...). If I press the "move table" button it will kick out the same "servo drive error" message. I have checked all of the fuses, removed all of the boards and looked for bad solder joints, checked grounds, incoming voltage etc. I have wasted my time by contacting the manufacturer, who states "those machines have been obsolete for a long time. We do not support them anymore". I swapped the cables from the amplifier boards, to see if one of those was bad, since in the "home mode" it moves "Y" 1st, no change. I did notice today, that if I press and hold, several times, on the move table button, it will eventually go to the screen that flashes caution home not found. When I get it to that mode, as soon as you press either the "X" or "Y" move table buttons, it instantly gives me the same servo drive error. Maybe I am thinking wrong, but if that happens, wouldn't the issue be something that is causing the problem before the amplifier boards? I use this for hobby work, and I do not want to dump $750 into a board that does not fix my issue. I would assume that the manufacturer had some testing procedures, that would tell you how to determine what the issue might be. There are multiple lights on the cards, some red, some green, some lit up, some not...If I knew what to look for, maybe I could narrow it down further. Any help is greatly appreciated!

I had one of those for years. The only time I remember getting that error message was because the Z needed to be manually pulled down a few inches at each startup prior to homing. If you forgot to do that then that "servo drive error" message would appear.

The black and white gen 1 MillPWR's are all but obsolete. You can only get the scale new from Acu-Rite, but those are custom made scales.

Looking at your hard drive, you should have a 4 wire connector with 2 black, one yellow, and one red wire coming to it. Unplug that and check for VDC from black to red and black to yellow. What voltages are you getting for each? The 12VDC signal (black to yellow) powers alot of your motion, including your BMDC card. That is the long skinny board next to the motherboard. On that board, you should see a blinking green light. Is that light blinking every other second, or once every 3 seconds? If it is once every 3 seconds, your BMDC is not communicating with your machine and could be the likely culprit of the issue.

Jon
H&W Machine Repair

Thank you for your response. The voltage between black and red is 5.13 volts. Between black and yellow is 12.93 volts. The flashing green light occurs about every 2 seconds, certainly not every 3. Unsure where to go from here. I have replaced all the servo drive boards with known good boards. (on loan from a retired repair guy) I replaced the card that is on the panel with the servo drive boards. Also replaced the entire servo drive card, panel assembly (unsure of the correct terminology). I disconnected the cables to the servos, same issue. Replaced the cables to the servos, same issue. When this first began, I had nothing on the monitor when it tried to start, I think the thing that got me back to having a DRO was cleaning the big cable (looks like an old school printer cable). Everything acts like it will be fine, as it starts it has the correct beeps, DRO loads everything seems ok, until you try to home or move the table. Not sure if this means anything, but the issue occurred while running a program and it was taking a pretty heavy cut.

12.93 is EXTREMELY high and is most likely why your BMDC is dead, which is what the light blinking once every 3 seconds tells us. Well, that tells us that the BMDC isnt communicating properly.

You can get a replacement BMDC (they are the board used in the Bridgeport EZ series CNC controller) for $1,500 plus a $500 core charge. You will also need a new computer power supply, but those are getting more and more scarce to get. Can you post a picture of your power supply?

Jon
H&W Machine Repair