At 10:53 AM 11/14/2003 -0300, you wrote:
>Hello people,
>
>         Have the following problem:
>
>         We (me and Dennis Crawley, also a piclister) built the abobe
>circuit to control, using PWM, the speed of a series wound motor. It
>worked fine at the factory, with no problems until we bring it to my
>place, where I have no GROUND connection.
>
>         The problem it presented was that it worked fine for a few days,
>one day, I live my place for about an hour and a half and leave the
>board powered, but with out any input signal (no PWM). When I came back,
>I turn on the control board, wich only sends some PWM to the power board
>and then I couldn't stop the motor anymore, even if I disconnect the PWM
>source from the power board.
>
>         Okay, I changed the FET (by the way it's a IRF 730) and though,
>ok, perhaps it has to happened, let's see if it happens again. It worked
>fine the rest of the day. When my day finished, I just unplug everything
>from the mains and leave it there.
>
>         This morning when I turn on the boards, it didn't work again,
>but this time the motor doesn't receive any power at all, I know that
>there is pWM, the 300V bus is powered,....
>
>Any experiences to share?

Where are the MUR1520s located? How long are the wires to the motor?

Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com

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