[RustedOut]

Been running my mill using Gecko 320’s on X and Y and a 320X for Z for many months without any problems. Last week I started it to run a small job only to find the Z motor won’t respond to either keyboard, mouse commands or MDI commands.

Matter of fact, the motor doesn’t even seem to be under power as I can rotate the ballscrew by hand with no resistance from the motor. Taking a voltage reading with a multimeter to the power supply of the 320X, I get a strong stable 79.0 volts. Taking a reading at the arm+ pin I get 73 volts and from the arm- pin I get 4.8 volts.

On the other two drives I get the same 79v from the power supply, but get 38v at the arm+ pin and 39v on the arm- pin.

The step and dir signals for all three drives look close to identical when viewed on an oscilloscope. Commons on all are 5v’s. I have US digital HEDS encoders on X and Y with a capacitor at the encoder per Geckos recommendation.

On Z I changed the HEDS to a EM-1 reader head when I installed the 320X. On this drive, the enc 5v pin measures 5.02v, the A channel measure 4.25v and the B channel measures 4.25v.

The voltage readings on arm+ and arm- being significantly different on the 320X than the two 320’s caused me to look at the signal on my scope. I’m seeing a good square wave signal on the 320’s while on the 320X I see a rectangular wave. If I try to jog Z I see the signal reversing quickly and am guessing the voltage readings I've taken on the 320X would swap pins. I never measured it though. I didn't see that so much on the other two drives probably because they are so close to being equal. On edit, I did take a look at arm+ and arm- on the 320X which is back on my Z axis and the voltage I noted stayed on the noted pins. The multimeter flickered while I hit the jog button, but came right back to what it was.

Thinking I may have a drive problem on the 320X, I swapped in my old 320 that used to be there and found I have the same problem with it, all readings being very similar to the 320X, especially the arm+ and arm-. All these values were taken with no input from Mach3 to the breakout board commanding moves. Just a static condition. The breakout board is a C11G from CNC4PC.

Puzzled, I moved the EM-1 reader head to my X axis and installed the 320X in that position as well. The drive functioned perfectly with no adjustments needed. I moved the original X axis 320 to my Z axis position after I installed the old HEDS reader and a capacitor to that encoder and got the same condition I’ve been experiencing there. So now I’ve swapped drives with no change and swapped encoders with no change.

I have a spare servo motor and decided to go ahead and install it in place of the newer motor I’ve been using. No change, motor still seems unpowered. Voltage readings remain the same as noted above.

I’ve been through all the wiring I believe several times in the past 3 or 4 days and find nothing. I’ve checked continuity from end to end on the encoders and on the drive to the breakout board and find no issues. My motor power supply and my 5vdc power supply are grounded to my star ground as is the other components requiring it. That is the common or - dc leads are grounded to the star ground.

I have been messing with some settings in Mach3 preparing to make some additions in the near future and thought I may have inadvertently changed something in there. I pulled up my earlier unchanged Mach setup and tried with it only finding the same problem.

I guess I’m officially stumped at this point. I’m not an electronics person, so what I’ve done trying to trouble shoot this has taken me quite a bit of time as I think through what I’m doing. Then evaluating the results. So it’s entirely possible I’ve missed something or misinterpreted something. Hopefully I’ve provided enough info on the problem and the details surrounding it. I’ve read through over 40 pages in this forum trying to find a similar issue, but found none. I’d appreciate any advise on this problem. I considered a phone call to Gecko, but this much information is hard for me to convey or even remember in a short phone conversation. And I'm not so sure it's a drive problem, it's just showing up there right now.

Thanks
Bob

[whateg01]

Just replying to see what ideas others have on this. I'll bet the solution is simple. Like a needle in a haystack simple.

Dave

[RustedOut]

I did some more investigating and decided to disconnect the Z motor and one other to see how the arm+ and arm- looked without them. I disconnected the X motor and took volt readings at that drive and found nearly the exact same voltages as I was seeing on the Z drive with the motor connected to it. 73 something volts on one pin and 4 something volts on the other.

While on the 320X on my Z with the motor disconnected, the volt readings dropped to mv's and were mostly equal. The signals on the scope were both rectangular now with the only major difference being the voltage. The timing was similar. Still no clue what this is telling me, but I find it interesting.

Bob

[RustedOut]

Remember I said I'm not an electronics person? My friend Dave came over last night to help me figure this problem out. The statement I made about the X drive signals looking like Z with the X motor disconnected was pretty telling. Only I didn't know how to take it. Dave found a loose power cable that ran out of my control cabinet to the Z motor as the problem. He was right about it being a needle in a haystack. Problem now solved and I'm stress free once again.


Bob