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IndustryArena Forum > MetalWorking Machines > Mori Seiki lathes > SL-2b Powering down during operation
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  1. #1
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    SL-2b Powering down during operation

    I have a Mori SL-2b with a Yasnac2000GII control. It keeps powering down for no apparent reason. It seems to run better when it is in an automatic cycle, however sometimes it does it even then. I'll just be running along and then bam! the screen turns off and the turret continues moving in whichever dirrection it was going until the chuck comes to a stop. I have had several instances where i would be feeding in the Z axis and this will happen and the turret will jump into the chuck. The only fix i have found is to turn it back on and pray it doesn't happen again. Any Ideas??

  2. #2
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    I will suspect of Power supply.
    On Electrical cabinet you have it on left side.
    Control for PS comes from a slim relay board mounted on left door
    Same cabinet.(bottom of memory boards)
    Perhaps one of them could be faulty.

    As you describe failure, all power is shut down suddenly as blackout.
    You can get somebody to power on the machine while you observe sequence of power at relay board mention and isolate which one actuates to power on Power supply.
    Then you can swap that relay.
    I wish you success.!
    Robby

  3. #3
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    I'll check this out in the next day or two and let you know. I think you are probably on the right track. Back when i first started having this trouble, I noticed one of the relays was making some noise that didn't sound quite right. I was told that it was supposed to do that so I dismissed it. I think I'll go ahead and change it out. Just have to find a place to get another relay. Thanks for your help.

  4. #4
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    See if it does it in the same spot in axis travel. I've had numerous problems on 2s and 3s with the cables shorting on the flex wire way in the back.

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    I replaced the relay that clicks when the power button is pushed. Still powering down. When the machine shuts down it doesn't seem to matter where it is. I have noticed however when the shut down happens, the Z axis jumps in the minus dirrection. (Bent a partoff tool in half yesterday) Another thing I noticed... In the left cabinet there are two boards. The one on the right has a bunch of capacitors on it on the lower left side. These caps will shock the hell out of you if you touch them. In my experience, they are not supposed to do this. I replaced them all and it didn't make any difference. Still shutting down and they will still shock you. Maybe a loose ground somewhere?

  6. #6
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    The latest

    Ok, So I bought another SL-2. I've started swapping parts back in forth in hope of finding the problem. So far I've swapped all of the Ice cube relays. And for the heck of it I swapped out the X and Z servo boards. Still having the same trouble. So i put all the parts back in their respective machines. Today when messing around with the machine, instead of completely shutting down just the servos went down. At this time I smelled something hot or burning. I went to the back of the machine and found that the large capacitor above the cabinets, below the z axis limit switches was putting off a lot of heat and that was where the smell was coming from. Should I replace this, or do you guys think something else is causing it to get hot? Thanks again.

  7. #7
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    Sure thats a cap? Sounds like you are talking about the Regen resistors for the servo amps. They are supposed to get warm.

    If they get hot just sitting, that means the axis motor is over working. Think you might have a bad/dirty Tach on Z motor and possibly a shorted motor. Bad tachs on those always make the axis jump, and every one i've seen for some reason jumps in the - direction.

  8. #8
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    Well I pulled off the tach. There was a fair ammount of dust in the housing so I blew it all out. The brushes and wires looked to be in good shape. Unfortunately I broke one of the brushes when putting it back on. I'll let you know how it works out when I come across a new one. Thanks again for your help.

  9. #9
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    Ok I've replaced the tach, both servo boards, the resistor, and the Transformers, and the relays. Still doing the same thing, except now when I am in full rapid X moves fine. Moving Z shuts the machine down immedietly. I can still rapid Z at half speed. Pulling my hair out here. Even called out a service tech, He looked at it for a couple mins, told me it was too old to fix and left.

  10. #10
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    Hey Buddy
    I would swap Z axis Motor complete from the other SL 2B
    90 % you will solve it there.
    Reading the whole story it seems as Encoder problem, because normally at lower speed you can rapid axes, but an encoder never will shut down the machine.
    I believe your Z axis motor is shorting to ground and thats when machine goes down.
    You are a little step away from success.!
    Robby

  11. #11
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    Well, good news and bad news. I replaced the whole motor. No luck. This morning i decided to replace the whole z axis servo pack. Got the resistor to stop overheating and no overload alarms. Great news!!!! Now here's the bad news, It's still doing the shut down thing every so often. WTF?

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    Forget to mention in my earlier post. Thank you to everybody for your help this far!

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