Re: Fanuc spindle going nuts
Disclaimer: I am not a Fanuc tech, so my suggestions should be taken in the general sense only...
If possible, I'd have a look at the control input signals going to the drive to see if it's being commanded wrong. I'd also have a look for cracked solder joints.
I don't know how your spindle drive is commanded; but if it's +/- 10v analog; an intermittent connection somewhere in the chain (not necessarily in the wiring) could conceivably cause this behavior.
Also - you could be aware of this, but I'm going to leave it here just in case (or for anybody else who reads this):
https://youtu.be/xaELqAo4kkQ
Re: Fanuc spindle going nuts
Quote:
Originally Posted by
__Britt
Disclaimer: I am not a Fanuc tech, so my suggestions should be taken in the general sense only...
If possible, I'd have a look at the control input signals going to the drive to see if it's being commanded wrong. I'd also have a look for cracked solder joints.
I don't know how your spindle drive is commanded; but if it's +/- 10v analog; an intermittent connection somewhere in the chain (not necessarily in the wiring) could conceivably cause this behavior.
Thanks for the advice. Its is indeed a wired connection not a optical connection so i want to sniff all the signals but i am not getting a signal loss error on the drive. I will check so see if the data is getting through correctly without any corruption.
The driver boards looked in perfect condition so breaks around traces or damaged components. I cant test the board under power. IGBT had no problems, i checked with a multi and then a diode checker. There was large capacitor on the board that looked very slightly bulged. I am suspecting it could be on its way out... Or the cause of the problem.
The signals to the motor look crazy so where ever the problem comes from its before the motor wires. Motor its self was fine.
Going by your advice i am guessing its a either a corrupted data stream from an encoder or the signal into the driver.
I dont have a scope i can use to check the encoder pulses. Can i use a frequency counter on a multi meter?
I know i should have a 1v sine wave and if i spin the motor with another motor i should be able to check for a consistent frequency out.
Re: Fanuc spindle going nuts
Replying to myself I know but...
Looks like it's a problem with the motor decoder. I checked the servo parameter screen and there was no movement for the load, gain and position readings when turning the spindle by hand or under power.
Will change the decoder and check the cable.
Re: Fanuc spindle going nuts
Quote:
There was large capacitor on the board that looked very slightly bulged. I am suspecting it could be on its way out...
Classic issue on older equipment. I would strongly suggest replacing that cap (and any others that might be questionable). Electrolytic caps can develop leaks - even while the board is continuing to function - and the electrolyte is corrosive to the PCB. For collectors of older gear (ranging from test equipment from the 20's & 30's all the way through classic game consoles and personal computers) replacing backup batteries and capacitors is standard procedure for ensuring that the machines continue to survive. Manufacturing equipment - due to the environment that it lives in - has it particularly hard; with temperature & humidity swings, coolant in the air, etc.
Quote:
Looks like it's a problem with the motor decoder.
Decoder, or encoder? The encoder would be the device that attaches to the motor; and turns the physical position (or movement, if it's an incremental encoder) into an electrical signal to be sent to the control. The decoder is whatever chip (or part of a chip, or set of chips, depending on the system design and age) that takes that signal from the encoder and turns it into something that the rest of the control can use. Typically, "the rest of the control" is a microprocessor or microcontroller of some sort, but sometimes it's discreet logic, an FPGA, or an ASIC.
Re: Fanuc spindle going nuts
Encoder (hall effect sensor). However the Japanese parts book describes the sensor unit as a decoder.
Re: Fanuc spindle going nuts
Just to add to the story so far for anyone who has the same problem.
Testing the driver board under almost every circumstance it was found that the AL12 alarm comes up on the display for a half second on power up. You would miss it i you were not looking at the right time. I have seen AL12 before on drives and the solution was to swap the IGBT due to a blown transistor. However on retesting the IGBT it has no problems and putting a megga on the motor found no shorts. Having said all that the one time case of AL19 and the AL12 on start up is a definite sign of a dead driver and replacing the board is the only sensible thing to do.
I put all this to management and they just threw money at the problem and ordered a new board. 8 hours later the board arrives and is ready to be swapped in. I am worried without finding the root of the blown driver will result in another blown unit. I still also have my suspicions about the encoder side of things...
Will update with the final results.
Re: Fanuc spindle going nuts
its the Tach // carbon or oil on the brushes or feedback from Tach...loose wire/plug.
Good Luck on the mission
Re: Fanuc spindle going nuts
> However the Japanese parts book describes the sensor unit as a decoder.
Yeah... sounds like a bad translation... probably by someone who’s not very technical.
Wild guess on my part... perhaps there’s a loose connection (or was... it might have been fixed during the trouble shooting process) that caused an inductive voltage spike, killing the IGBT? I’m trying to think of what can do that kind of damage to an already working system...
Anyway... good luck with it! Hopefully it’s just a one-time failure.
Re: Fanuc spindle going nuts
Did you get your problem solved? I have a 3T controlled Tsugami Chucker the spindle threw a fit like you have described Load meter etc.. I started with checking the spindle motor I had a bearing noise I wanted to address anyway found some one had used crimp on but connectors on the leads almost as bad as scotch locks on trailer wiring !! Soldered/shrink-tube that done then found bad IGBT's changed now a fuse blown . Local tec. suggested some kind of short in motor but that checks out ok got the fuses $20.00 ea. I guess I will try one to see if it works maybe the fuse went when the motor originally had its fit. Need to get this old girl up and running again and change the back up batteries. P.S. the Fanuc manuals do leave a little bit to the imagination !! Kevin