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Errors after ball screw support bearing swap -fanuc o-m

carl laniak

Aluminum
Joined
Dec 27, 2012
Location
South Carolina, United States
1995 Leadwell mcv 760-ap
Fanuc o-mF

Well... Despite the machine working fine for my needs... I could hear a slight grumble developing in one direction when the x-axis moved... Had a job coming up with some tighter tolerances and went ahead and got the ball screw support bearings and grease ordered...

Removed the x-axis servo... Red cap fanuc, as well as the bearing support housing... Took a few hours to make the tools I needed to disassemble everything but I got it and got the new bearings in there... It feels smooth as silk and totally solid which is nice after spending a couple late nights on a project I was a little nervous about.

Turn the machine back on and I'm lit up with 400, 408, 414, 424, 434 errors... Overload, serial not ready, axis detect errors.

The only electrical thing that I did throughout the entire process was to remove the power and encoder cables to that motor...

Any thoughts on first things to check?

Thanks,
Carl
 
I'm sure you checked the cables that you disconnected? Made sure they were clean, fully on, etc?


I have changed the bearings in similar leadwells to yours. I helped you a bit when you first got the machine years ago.


When we remove the bearings, we don't disconnect the motor. We uncouple it from the screw and just set it aside. Not because we've had this issue, just because we *can* without disconnecting.


So clean it, reconnect it, etc. Hopefully you didn't get a chip in your cable that shorted out or something. or hopefully it just isn't connected fully and you just gotta screw it in some.

Is it only the x axis giving the alarm?
 
I absolutely remember your help years ago....the machine had no parameters and you guided me through quite a few issues. Lucky me the machine has been really solid for something like 8 years now....I think I've only put about 1000 hours on it as a sole proprietor it doesn't see work every day (or even every week, really).

I after booting up and getting this error I did take the cables back off and I sprayed in there with electronic cleaner....there did appear to be some coolant residue that had found it's way in over the years, but I cleaned and dried that - then reconnected....no change. Same errors.

The drives are not getting power, there's a relay (connector?) in the cabinet that's blinking. I'll look in to what that is after I go pick up the kids at school.

It makes sense that you would avoid removing the cables....especially with an older machine....If I were to do it over again I think I see how that could be avoided....but for clearance on the bearing retaining ring bolt heads I decided I needed to get the housing out of the way...and not having done it before I assumed removing the motor was necessary :)

I'll take the connectors off one more time and blow them out with clean air....I don't see any fuses blown in the cabinet, as a side note.

Carl
 
I have not taken the cable connector apart. Are you suggesting I loosen the connector from the motor housing itself, to check whether all the wires are still solidly soldered in place? Should I remove the red cap first, is there anything under there easily visible to check?
I did use a deadblow mallet to persuade the housing (and thus, the motor too) to come off the frame...I guess that vibration could have disconnected a fragile wire connection....?
 
Well, everything you have posted could be caused by a bad connection. Need to verify all connections that were affected by the work are intact.

Not sure how hard you used the deadblow or where you hit. Encoders do not like shock……
 
I took the connectors apart yet again, they seem clean and I can't find any chips that I missed the first couple go-arounds.
The back side of the encoder connector (inside the red cap) was totally clean and all the wires were solid with the pins (I didn't use an ohm meter to prove it...yet.
The inside of the red cap was dry with not a hint of contamination.
Turning the machine back on (I also turned the screw/motor by hand some) and the only change is that there's now also an X-axis overtravel alarm...

If it's somehow the cable, which snakes it's way under the table and through some shielding back to the cabinet....is there some simple way I'm not thinking of to check the cable? I don't have an ohm meter that can reach that far, so testing continuity on each wire....I guess you would also want to check whether any of the wires were frayed and shorting to the frame?

I know 1% of what vancbiker and dandrummerman know, but I can't decide if I think it's the cable, or maybe just the encoder itself got jostled and has failed.

Any further guidance/direction appreciated...it seems like several of the problems I've had with these older fanuc controls have just been "take it apart and put it back together a few times and it'll work - AKA connection issues."

I'd order a used motor/encoder off ebay, but if my knocking the cast iron motor mount with a deadblow killed the encoder it doesn't seem possible that you could ship one UPS/FEDEX and have it survive???

Carl
 
I took the red cap off, and then the encoder too. All seems clean and clear in there.
I don't have, but I do have access to, an oscilloscope if anyone can point me to a (relatively) simple method to check the encoder itself.
Carl
 
possibly pertinent information:
The power supply is not powering up with the control.
no power to drives.
every fuse I can find checks out fine.

there is one connector blinking (connect/disconnecting) on the board below the drives and power supply. As soon as I can I'll get my books and try to figure out what that is....
 
possibly pertinent information:
The power supply is not powering up with the control.
no power to drives.
every fuse I can find checks out fine.

there is one connector blinking (connect/disconnecting) on the board below the drives and power supply. As soon as I can I'll get my books and try to figure out what that is....

You mean a relay LED is blinking on and off on the leadwell IO board? That's probably the alarm light on the machine.

The power supply for the drives and drives themselves don't have power? Not even a "-" or numbers indicating an alarm?

But the control is still coming on now?

Is this machine equipped with alpha drives (yellow vertical oriented drives, all side by side)
 
I have no idea and probably no help at all, but does the machine have absolute encoders?

That might be a reason why it did not like having the encoder cable unplugged.
 
You mean a relay LED is blinking on and off on the leadwell IO board? That's probably the alarm light on the machine.

The power supply for the drives and drives themselves don't have power? Not even a "-" or numbers indicating an alarm?

But the control is still coming on now?

Is this machine equipped with alpha drives (yellow vertical oriented drives, all side by side)


Yes, Alpha drives.
and yes, there are no lights at all on the fanuc power supply, or the spindle and axis drives, but the control does power up and the screen shows the errors.

I had some input from elsewhere, and was able to find a blown fuse on the inside of the fanuc power supply module. I replaced that with my only spare fuse, but it immediately blew again upon powering on the main power switch....I've ordered a few more. My other consultant suggested I should have unplugged the axis drives first to see if I can figure out if I have a short on the 24v side of things.

I'll do that when I have the new fuses. any other input appreciated!
Carl
 
So I would guess it is related to you moving the cables, and it is related to the x axis. This might not be the case; it could be anything, even unrelated to you doing any maintenance.


But on the continued assumption it is related to the x axis, I would disconnect the motor and encoder cable from the drive side, and try a power on. If still fails, disconnect further back until you can figure out what's blowing the fuse.

What fuse blew? Do you mean the black PSM? IIRC there's a 1 and 5 amp fuse (or 1 and 10? i don't remember offhand)

Did you disconnect any wires at the drives before you started maintenance? Could you post a screenshot of your drives so we can be sure you've got all the plugs in the right spot, etc?

Also do you have the motor leads on the correct spot (UVW) on the drive?

Just making sure we've got no wires crossed here (lol). Detailed pictures would be helpful. Its the closest we've got to standing right there with a multimeter.
 
So I would guess it is related to you moving the cables, and it is related to the x axis. This might not be the case; it could be anything, even unrelated to you doing any maintenance.


But on the continued assumption it is related to the x axis, I would disconnect the motor and encoder cable from the drive side, and try a power on. If still fails, disconnect further back until you can figure out what's blowing the fuse.

What fuse blew? Do you mean the black PSM? IIRC there's a 1 and 5 amp fuse (or 1 and 10? i don't remember offhand)

Did you disconnect any wires at the drives before you started maintenance? Could you post a screenshot of your drives so we can be sure you've got all the plugs in the right spot, etc?

Also do you have the motor leads on the correct spot (UVW) on the drive?

Just making sure we've got no wires crossed here (lol). Detailed pictures would be helpful. Its the closest we've got to standing right there with a multimeter.

I sent my rush job to a friend because I had a unavoidable trip mon/tues and family thanksgiving now... so I'm away from the shop and can't take any new pictures. I've attached a couple pics of the drives, and an internal shot of the fanuc power supply module (where the blowing fuse is).

As far as crossed wires... I literally did not open the cabinet before this all happened. I'm a sole proprietor and the only one with access to my shop at all, so there's no chance that anything there got switched and caused this.

I've circled the fuse that blows in purple....it's inside the PSM..... take the gray face plate off, then remove the yellow casing, and then behind the 2-digit LED readout are these two fuses....the 5A one blows. (in the pic the other fuse is pulled, but that's only because I was inspecting it at the time).

Hopefully that makes sense. When I have new fuses I'll try starting up without the motor/encoder plugged in, and if that doesn't work I'll try it with those cables unplugged closer to the control... If the short is inside the PSM I guess I'll be trading it for a refurbished one. Any other thoughts appreciated, I wish I had more experience/education with the electronics of CNC.

thanks,
carl

drives.jpg
PSM.jpg
fuse.jpg
 
Might be a dead short in the encoder cable?

Maybe someone else has more to input. But based on you removing the motor, and moving the cables around, there's gotta be a short. Or simply coincidental bad luck.

Those cables never move in that area normally, and the machine's 25 years old. Stuff gets stiff and breaks.

I'd disconnect the motor and encoder cables from the x axis drive. I can't tell if your x and y are on the same drive, kinda looks like it.

Hopefully someone else will also have more input on what to do when powering back up.
 
As it turns out, the fuse inside that power supply module blows even when I disconnect the servo amps from it....so I'm ordering a power supply from ebay. Crazy coincidence...
will report back in a week or two.
 
So,
Got my new-to-me power supply in and connected.
Boots right up with no error messages!

BUT....the x and y-axes both move in the opposite direction!
Z-axis and spindle go in their normal directions.

Before you ask, yes, the x and y do share a drive on this machine....but,
I am 99% sure I didn't ever unplug anything on that drive.

So,
is there a parameter that could have been lost when I switched the power supply module?
or did I mis-wire something?

The obvious question about phasing can't be the answer because T1,T2,and T3 coming in to the power supply are clearly marked and were always in 1-2-3 order....

EDIT: zero return does send the table in the normal direction....but it still wants to move opposite the +/- directions as normal (ie moving to the left the position gets larger, and I have to spin the mpg wheel opposite what I normally do)...

thoughts?
Carl
 
When I turn the mpg wheel clockwise (which has always made the table move to the right and the position value get bigger),
the table moves to my left.... the position numbers get bigger as expected.
hopefully that makes sense..

also, i edited my previous post to say that homing the machine sends it in the normal direction.... but does not correct the issues of the mpg wheel being reversed from normal and the position values moving opposite from normal....
 








 
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