Yaskawa Varispeed 505MT drive will not brake nor reverse

[Andy Fritz]

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

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[Redzilla]

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

[Andy Fritz]

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.

[Redzilla]

I sent you a pm.

I didn't get it just text me
606- 547 - 78six three

[Andy Fritz]

I just sent you a sms with my email.

Andy