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Fanuc OT Not Ready

wmpy

Hot Rolled
Joined
Dec 16, 2011
I have an early '90s Star CNC lathe with a Fanuc OTT-C control. I can't get it out of the "Not Ready" state. I have had the machine for over 15 years, so I am familiar with it, but this has me stumped.

At first I made the mistake of thinking this was the same as E-stop. It is not. I checked everything related to the E-stop string. However, this is a different circuit. What I have now is just the words "Not Ready" blinking at the bottom left of the screen when I turn the power on. There are no other alarms on the control or any of the drives. The hydraulics DO come on. If I press the E-stop button, trip the hard over travel switches, or trip the door interlocks, then I get an "Emergency Stop" message on the screen, which I can then reset and go back to the not ready state.

I've gone through all the troubleshooting I could with the tech from Star. He thinks it's a Fanuc issue. The Fanuc techs had me check a bunch of diagnostics. That all looked normal (to them). What they've got me looking at now are the servo drives. There are three dual-axis drives. When the machine is powered up, there are two green LEDs that should come on: +5V and DRDY. I'm not getting the DRDY lights. Fanuc says it's weird for those to not come on and not get any alarms. They suspect a bad axis control board. But there are 2 axis control boards. One handles two drives and another handles the third drive. I'm not getting DRDY on any of the three drives. So both axis control boards are bad?

If you've made it this far in reading my ramblings, I thank you. Tomorrow, I am going to see if I have the same of either of the axis control cards in any of my machines so that I can swap them out. I don't have high hopes of that changing anything. Then I will probably throw in the towel and have Fanuc come out to diagnose the machine. If anyone reading this has any ideas or suggestions, I'd love to hear them. Thanks!
 
What model Star? I still own a 2002 SE-16 with a 21i-T and a couple years ago scrapped out a 1995 SR-20 with a 16TT. I think other than one guy whose name I forget and is hard to reach in the New York office every Star tech I have talked to or met has been pretty incompetent. The guy in the NY office was the one who babysat the field techs sent out from that office by phone. The best guy in each office supports the tail chasing field techs, that is why they rarely help phone in customers. As for Fanuc it goes back decades working for the man, but their field techs were pretty inept also. Unless you are right next door and a Fanuc service call will be cheap I would not go that route if I were you.

First I would wait till Vancbiker chimes in, secondly call T.I.E. (615) 793-3244 they are a great Fanuc repair house. They will also try to help diagnose by phone and lay out the most likely culprits. You can then pull those likely culprit boards and send them to them for testing. If something tests bad the testing fee is applied to the purchase of repair or exchange. I have had many an OT drive repaired by them.
 
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.......First I would wait till Vancbiker chimes in, ......

Dang it, I was trying to ignore this thread :).

@OP: You say that you have done a bunch of troubleshooting already. Care to outline what you have done and what the results were? No point in me typing in a bunch of things for you to do if you have already done them and moved on.
 
@vmipacman: Yes, I do have the ladder diagrams for the machine.

@Dualkit: The machine is a Star KNC-20. The people I talked to on the phone at Star and Fanuc seemed pretty good. Then again, the machine is still broken down, so maybe not...

I ended up sending the entire control in to my local Fanuc repair shop. It is still under warranty from a previous repair they did. I'm hoping they will find something. I will update either way. Thanks to everyone for chiming in. At this point, it's a waiting game.
 
I hope they solve the problem at the repair shop. I would have started by going through the ladder logic and identify all the inputs that must be true for the control to enable. The ladder would have told you that. The lights you mentions may not enable until the prerequisite contrition a are met. Could be something like an air pressure sensor.
 
I hope they solve the problem at the repair shop. I would have started by going through the ladder logic and identify all the inputs that must be true for the control to enable. The ladder would have told you that. The lights you mentions may not enable until the prerequisite contrition a are met. Could be something like an air pressure sensor.

This ^. Not Ready is very much more likely to be something on the machine side of things not being correct to allow the control to enable than to be a control issue proper.
 
For what it’s worth...
I am skeptical about most repair shops (of any type). I think only the really good ones will know what to do with a 20 year old fanuc. They might just replace a few aged capacitors they found, charge you 700 bucks, and tell you that’s all they could find. I would suggest making a pdf copy of your ladder and sending it over and asking them to simulate all the inputs to get the control to enable. That way you know it works when it leaves their place and you know what inputs the control is looking for. Then you know where to look in your system for contacts not closing etc.
Btw, did you really send the whole fanuc control? Isn’t the OT actually a bunch of boards and I/o cards? Plus monitors etc. Seems like a nightmare to send the whole control, or did you just send a few specific boards?
 
@vmipacman: Yes, I do have the ladder diagrams for the machine.

@Dualkit: The machine is a Star KNC-20. The people I talked to on the phone at Star and Fanuc seemed pretty good. Then again, the machine is still broken down, so maybe not...

I ended up sending the entire control in to my local Fanuc repair shop. It is still under warranty from a previous repair they did. I'm hoping they will find something. I will update either way. Thanks to everyone for chiming in. At this point, it's a waiting game.

I only dealt with California and New York Star offices, maybe your results will very. Anytime I complain about Star parts and service no one sticks up for them. I ran a KNC-20 about 30 years ago for a short while, it was the only Star in a department full of Citizens, I don't remember much about it.

The entire control? You mean every board in the whole machine?
 
I sent what I consider to be the entire control: the main board with the power supply, PMC-M, I/O, memory, sub-CPU, and 2 axis controller boards all plugged in. It comes out as a nice unit- actually smaller than some spindle drives I've had to send out. I didn't include any of the drives or the monitor. I did leave the battery pack plugged in so that memory isn't lost. We'll see what they say. I tried everything I could think of on the machine side including looking through the ladder, but to no avail. Hopefully there's something in the control that can be easily fixed.
 
The repair shop found nothing wrong with my control.

But, I did find the problem. A few years ago, I replaced the keypad membrane on this machine with a cheap one off Ebay in an effort to avoid paying Fanuc's high prices. I've hated the feel of it ever since and have never bought another one. Well, the membrane cracked around the Reset button and was holding the button in constantly. Once I freed up the button, the machine fired up like normal. I am quite happy to have found the problem but also amazed that such a little thing could have wasted so much time. Thanks again to those that tried to help.
 
.......I am quite happy to have found the problem but also amazed that such a little thing could have wasted so much time. Thanks again to those that tried to help.

Glad that you found it.

If you look back to post #4 you'll see a request to find out what you had already done to trouble shoot the problem. Had you done that, myself or others would have asked you to post the content of some Diagnostic addresses. Based on that info a stuck reset signal would have been identified and you would have had your machine running 2 weeks ago.....
 
Wow, I never heard that one before. I hate to think the time and effort plus the bill for having the control tested.
 
Thanks, Vancbiker. I was feeling pretty good about myself for finding the problem. Then I read your post. It brought me back down a few notches. Gotta stay humble.

Star said it was a control issue, Fanuc said possible bad axis card. I didn't have any cards of the same model to swap out, so I sent the whole unit out for testing. It was still under warranty from a previous repair, so there was no charge for that. It seemed like the best course of action at the time.

As far as the request to explain what troubleshooting had already been done, I couldn't really tell you. Both the Fanuc and Star techs had me check so many diagnostics over the phone that I had no idea what I was checking. Maybe I should have made them explain what each diagnostic was or taken notes, but it was too late for that. So, I didn't want to waste any one's time with incomplete information. I had already posted everything I knew for sure in the original post. Hope that makes sense. The machine is back up and running now, so all's well...
 








 
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