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IndustryArena Forum > MetalWorking Machines > Mori Seiki Machines > Mori Seiki lathes > Yaskawa Varispeed 505MT drive will not brake nor reverse
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  1. #1
    Join Date
    Jul 2005
    Posts
    205

    Yaskawa Varispeed 505MT drive will not brake nor reverse

    Hi!

    This DC spindle drive stopped reversing and braking but otherwise seems to work ok.
    There are no alarms. I know the main pcb is to blame as it works fine after testing with another borrowed main board.
    This drive gets +-10VDC from the Yasnac 2000B control and should change direction based on the signal polarity.
    I have searched the web and Yaskawa for schematics but no luck so far.

    Does anyone know which components are the usual suspects? I have attached a picture but not sure the max allowed resolution is sufficient.
    The missing electrolytic capacitor in the lower right area had to used for the loaner board.

    Also; this drive has a separate Thyristor Exciter unit for the field which has a shorted NEC 20P6S stud SCR I need to replace. There are no data sheets available and NEC does not have any specs.
    Is there any less obsolete SCR on the market I could use?

    Cheers,

    Andy

  2. #2
    Join Date
    Feb 2016
    Posts
    116
    Quote Originally Posted by Andy Fritz View Post
    Hi!

    This DC spindle drive stopped reversing and braking but otherwise seems to work ok.
    There are no alarms. I know the main pcb is to blame as it works fine after testing with another borrowed main board.
    This drive gets +-10VDC from the Yasnac 2000B control and should change direction based on the signal polarity.
    I have searched the web and Yaskawa for schematics but no luck so far.

    Does anyone know which components are the usual suspects? I have attached a picture but not sure the max allowed resolution is sufficient.
    The missing electrolytic capacitor in the lower right area had to used for the loaner board.

    Also; this drive has a separate Thyristor Exciter unit for the field which has a shorted NEC 20P6S stud SCR I need to replace. There are no data sheets available and NEC does not have any specs.
    Is there any less obsolete SCR on the market I could use?

    Cheers,

    Andy
    I have a whole set of boards I'll sell you for a really good price, I also have the schematic for the spindle drive. PM me your email and cell number

  3. #3
    Join Date
    Jul 2005
    Posts
    205
    Quote Originally Posted by Redzilla View Post
    I have a whole set of boards I'll sell you for a really good price, I also have the schematic for the spindle drive. PM me your email and cell number
    I sent you a pm.

  4. #4
    Join Date
    Feb 2016
    Posts
    116
    Quote Originally Posted by Andy Fritz View Post
    I sent you a pm.
    I didn't get it just text me
    606- 547 - 78six three

  5. #5
    Join Date
    Jul 2005
    Posts
    205

    Re: Yaskawa Varispeed 505MT drive will not brake nor reverse

    I just sent you a sms with my email.

    Andy

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