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  1. #21
    Join Date
    Feb 2010
    Posts
    31

    Re: al-12 fanuc spindle alarm

    I just got thru rebuilding the spindle drive unit. I redid the PCB and replaced all transistors, diodes, and caps......replaced the transistor pack and reassembled the drive.....every thing works (fingers crossed on tomorrow morning)

    I had the spindle on for over 2-hours running parts today and it seems fine....I cannot thank you guys enough here on the website....for all your comments and help......I learned so much rebuilding the board...very grateful to all of you guys.

  2. #22
    Join Date
    Sep 2012
    Posts
    106

    Re: Fanuc spindle alarm AL-12

    metalmover, what diodes did you end up replacing? I have a similar board, same optocouplers, fets, etc, just mine has double the chips since its a dual transistor module drive. I just replaced the faulty transistor, one of the outputs was shorted to V-, and the spindle will start 1/10 times, but isnt very happy about it, and the load meter goes through the roof. Once its spinning it will stay running, and the load levels out. But im still thinking I have a bad driver FET and need to get this machine up and running again. Any advice? I want to order parts this weekend if possible.

  3. #23
    Join Date
    Sep 2012
    Posts
    106

    Re: Fanuc spindle alarm AL-12

    "not an expert", any advice on what the hybrid is? Im not familiar with this type of spindle drive. The ET191 Fets, the optocouplers, and the Fet diodes are no problem replacing here. Anything else I should check? The TM tested ok, and the spindle will run. I just think I have a FET that is hanging. I should mention that I bought this machine broken, and the fans in the cab were not working, so Im sure something has overheated in its life. The Ladder EEPROMS were erased im thinking due to the heat. Just had Uptime Electronics retype the whole ladder into new chips, only issue left now is the damn spindle drive.

  4. #24
    Join Date
    Sep 2012
    Posts
    106

    Re: Fanuc spindle alarm AL-12

    update. there was a BAD TM, replaced it. One of the .3 Amp fuses next to one of the Fets was blown. Found out after I scoped the Fets and found one was inactive. Must have blown when the TM went. Replaced fuse, boom, runs like a champ!!! Only thing I cant figure out now is how to shift from low gear to high, and I have a bad spindle shift support bearing. Ugh.

  5. #25
    Join Date
    Aug 2007
    Posts
    138

    Re: Fanuc spindle alarm AL-12

    Well I am a little more than just pissed off. I just got the dreaded AL-12 on my A06B-6044-H106. Just had this unit rebuilt about 100 to 200 hours ago. I don't understand why this thing seems so fragile. All the computer power on this drive and it can't protect it's self better?

    I was cutting a small part at max spindle speed of 6K. All went well until the M5 was issued. The spindle began to slow then bang, alarm and then it just coasted to a stop. I disconnected the drive from the motor and the AL-12 still happens as soon as a M3 is issued. I found one of the new fuses blown on the driver board. One of the 1 amp ones (I think there are two of those). I even have the deceleration set to a long gentle profile to prevent power spikes.

    Seems like just my luck. Since I have owned this machine I have had to have the spindle motor rewound and about a year later the drive rebuilt and now this again...ugh!

    At this point I will order a replacement fuse but am not expecting that to fix it ...we shall see. Then I will have to decide on a repair strategy.

    (grumble, grumble....)
    Dan

  6. #26
    Join Date
    Aug 2007
    Posts
    138

    Re: Fanuc spindle alarm AL-12

    OBTW, anyone have a part number for that little plastic square fuse?
    Click image for larger version. 

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  7. #27
    Join Date
    Sep 2012
    Posts
    106

    Re: Fanuc spindle alarm AL-12

    The al12 can also be a FET module. They are fairly cheap on ebay. I had to replace one in my mycenter that shorted. They are big black bricks with 9 big bolt lugs. There are guides online on how to test them.

  8. #28
    Join Date
    Sep 2012
    Posts
    106

    Re: Fanuc spindle alarm AL-12

    Fanuc fuses that size are either DM or HM iirc. The PN is the type and amperage. Like a 3.2 DM is just DM32. There are 2 styles, they look almost the same make sure you get the right ones. There's a few places online that sell them for about 5$ a pop.

  9. #29
    Join Date
    May 2008
    Posts
    84

    Re: Fanuc spindle alarm AL-12

    Quote Originally Posted by Dancy View Post
    OBTW, anyone have a part number for that little plastic square fuse?
    https://cnc-specialty-store.com/fuse.../dm-daito-fuse

    Who did the repair? I had mine done by PLC center (Radwell). I can't remember what the warranty period was (6months?) But regardless, you should still have some warranty time on yours. I would push on whoever did the repair. I have at least 2000 hours on mine since, but my max rpm is only 4K.

    Also. Some of the repair shops don't replace the opto-couplers, and driver transistors that are supposed to be the real culprit that cause the power transistors to blow. Sounds like this might be a source of your failure?

    For production runs I don't have an M5 after each op. I just let the spindle run during the tool changes. I also only use G96 on features that need it. Just using constant RPM (G97) on a lot of the cuts. It's the stop/starts that spike the drive.

  10. #30
    Join Date
    Sep 2012
    Posts
    106

    Re: Fanuc spindle alarm AL-12

    Keeping the spindle running only works on machinrw that have a neutral. My Cincinnati is direct drive and my kitamura is 2 speed gearbox so I have to do m5 before tool change, but maybe Dancy machine is different. But you're right about the large power transistors being the culprit for other issues.

  11. #31
    Join Date
    May 2008
    Posts
    84

    Re: Fanuc spindle alarm AL-12

    I would also make sure your cabinet fans are working well. My spindle drive blew when one of the cabinet fans was blown. It had been out for a while, so that didn't help. But I had been running the spindle at max rpm (really small parts) with LOTS of stop/start cycles for several days. Stop/start is what kills motors, due to all the heat that is generated during each start/stop. It is better to let the motor run, than constant stop/starts. This applies to any electric motor.

  12. #32
    Join Date
    Aug 2007
    Posts
    138

    Re: Fanuc spindle alarm AL-12

    Thank you all for your responses,
    With the information provided I have made the decision to attempt repairs on my own. I did not know the FET blocks could be obtained at those low prices, the rest I can ferret out. Results pending I will post my findings.

  13. #33
    Join Date
    May 2008
    Posts
    84

    Re: Fanuc spindle alarm AL-12

    Quote Originally Posted by Dancy View Post
    Thank you all for your responses,
    With the information provided I have made the decision to attempt repairs on my own. I did not know the FET blocks could be obtained at those low prices, the rest I can ferret out. Results pending I will post my findings.
    Good luck with that. Seriously. I would replace ALL the driver circuitry, including the caps.

    I have decades of experience with component level repair of electronics, with a smattering of high power. And have done minor repairs on servo drives, including IGBT/FET transistor packs. I considered repairing my spindle drive when it blew.. But after some careful research on this particular Fanuc spindle drive I opted to let the pros do it. Estimates were from the eye watering range of $5K-$6K, down to a more reasonable $1.2K from PLC center. They (PLC) now are at a 2 year warranty.

  14. #34
    Join Date
    Aug 2007
    Posts
    138

    Re: Fanuc spindle alarm AL-12

    I agree Claya, if I can't assemble the required parts you suggest at less than half that cost I will not risk it and simply send it in for repairs.

  15. #35
    Join Date
    Feb 2011
    Posts
    640

    Re: Fanuc spindle alarm AL-12

    you should be able to find transistor modules cheep on ebay, the big block is likely whats giving you the al12, but check the 3 lug transistor for braking too- sometimes chips/crap get into the usually hidden regen resistor and short it out, going into regen during slowdown it could flash over and poof goes the switching transistors...

    something else to watch out for- these things will go into regen if drive input voltage hits right around 242 volts- weve had a lot of failures on purchased machines with transformers tapped for 240 out- during voltage rise on weekends, if a cap bank controller not set up right or whatever, our 480 often tips in around 490-500 on weekends...we started tapping all our isolation transformers to 504 primary, eliminated 90% of our drive failures- i started doing this about 15 yrs ago when 4 daewoo v500s all blew supplies one weekend- they came in tapped at 460, maint hooked them up, first weekend, pow- like 30k damage to drives/supplies(8k ea exchange). i wnt and checked, our vAR controller had a shorted output, putting leading power factor, voltage at over 500 during light loading, combines with the low taps, we were getting around 250 to the drives, they smoked just sitting there...also had them start turning off disconnects during off shifts.

    anyways, hope you can find a 50 dollar igbt block, and maybe get lucky. other things that tear them up are the optocouplers mentioned a few posts up- cheep and fairly easy to change, a buddy with a repair shop said he started changing them ALL 20 years ago due to warranty returns- and these things aint getting any younger the tail bearing of the motor can be a issue too- we have a LOT of these where the mag sensor is fading(the permanent magnet goes dead over time- no way to fix- just replace) and often the air gap has to be near touching for a weak sensor to read- but then a loose tail bearing can cause rubbing/gap changes that freak it out under load changes due to belt/gear loads rocking the shaft a few thou...most of the time its not the bearing, but the slip-fit in the housing worn...

    lastly, you can go thru the keypad and change the braking current- drop it way down to 10-15% and most mills will still work fine, just might take a extra second for a toolchange...limiting regen current cant hurt- acc/dec time might help, but some still orient harshly, limiting regen works during orient too- depends on the low parameters that controls limits, we run ours to limit during acc/dec

  16. #36
    Join Date
    May 2017
    Posts
    19

    Re: Fanuc spindle alarm AL-12

    Anybody on this feed that can help me?
    I have an AL-12. Thread is old but I have questions!

  17. #37
    Join Date
    May 2008
    Posts
    84

    Re: Fanuc spindle alarm AL-12

    Ask away. Just be sure and read through the thread. There is some useful info in this one.

    Quote Originally Posted by Bodesi View Post
    Anybody on this feed that can help me?
    I have an AL-12. Thread is old but I have questions!

  18. #38
    Join Date
    May 2017
    Posts
    19

    Re: Fanuc spindle alarm AL-12

    I'm not an electrical engineer so I was going to ask if it is worth a go to try and fix this myself. But I see your reply below.

    My machine is for mostly hobby use. I would like it working again, but I am looking into trying to fix it instead of throwing money at it.

    I will contact PLC maybe $1200 will be worth it, vs the headaches of fixing it.

    I got my hands on the manual for the drive. Testing various things now. It seems the transistor module may be the culprit. But reading this thread it seems like anything can go worong. Was hoping for an easy fix.

    I am going to re-read this thread and test as many things as I can.

  19. #39
    Join Date
    May 2017
    Posts
    19

    Re: Fanuc spindle alarm AL-12

    OK here is what I intend to do"
    Replace the following (as per metalmovers post)

    1.) Transistor (in my case it is a "ET191"...quantity 7)
    2.) Diode for transistor (self explanatory...quantity 7)
    3.) Photo coupler (mine is a "TLP550"....quantity 7) These are usually the culprit, from my research.
    4.) and the Main Transistor Module (
    A50L-0001-0125 #A0)

    But what Caps need/should be replaced?

    I know there is a big on at the back (
    A42L- 0001-0142#A) is it necessary to replace it?
    are there others?

    Anything else I am missing?

  20. #40
    Join Date
    Aug 2007
    Posts
    138

    Re: Fanuc spindle alarm AL-12

    from my experience with this and many other older systems, I would suggest replacing any electrolytic capacitors in the power build up chain.....these things are relatively cheap and tend to "dry up" with age and no longer perform as specified.

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