Re: [CAD_CAM_EDM_DRO] Re: servo brake problem

----- Original Message -----
From: "Keith Clark" <mail@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Friday, August 27, 2004 8:30 AM
Subject: [CAD_CAM_EDM_DRO] Re: servo brake problem


>
> Lance,
>
> Thanks for the ideas. I think that the idea of power to turn off the
> brake must be true since the brake stays on even when the machine is
> off. I tried to test continuity and there is no connection from the
> input to the ground side of the terminal block across any of the
> solenoids including the 2 that function properly. There also a diode
> somewhere accross all of the solenoids according to the schematic,
> but I can't find the one across the brake solenoid. I do see the one
> for the speed control solenoids. I am not sure why a diode is needed
> for DC current.

The diode is there to suppress the back emf (reverse voltage) pulse when the
solenoid is de-energized. If the solenoid is driven by a transistor or other
solid state device it can be damaged by the back emf pulse. The diode
conducts when the magnetic field collapses and it sucks up the energy.

The diode should be on the solenoid terminals and must be anode to ground
and cathode to positive and should have a 400 -600 volt rating. common
1N4004 diodes are a standard.

The use of a diode on dc posered coils (relays & solenoids) is standard good
electricial engeering practice.

Hugh

Everything did work before we began the
retrofit 6
> weeks ago. I did hook up what I thought was a proper connection to
> put power from the DC powersupply to the brake solenoid and blew the
> fuse in the powersupply so there might be some other problem as well.
> At least I appreciate the logic that not power should mean solenoid
> off and not powered. That will help me trace it through I hope.
>
> Thanks
> Keith Clark
>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, "Lance Hopper"
> <snaggletto@c...> wrote:
> > Hello,
> > Logically, if power were removed from the solenoid, during an E-
> > stop for example, the spindle should be in brake mode. When the
> > solenoid coil is charged, the spindle should be free. Just my
> guess,
> > mind you.
> >
> > Can you check and see if there is continuity through the coil? No
> > electricity can flow through the coil if it's broke.
> >
> > If you are sure you have the right voltage etc..., maybe it's
> simply
> > stuck, or binding mechanically. Did it work correctly recently?
> >
> > --- In CAD_CAM_EDM_DRO@yahoogroups.com, "Keith Clark" <mail@t...>
> > wrote:
> > > Hi guys. Can't seem to get the brake to turn off on the
> Bridgeport
> > > Boss 6 retrofit project. While waiting for the new motors and
> > > repaired motion card, I have been trying to get control of the
> > > solenoid controlled spindle brake. I don't understand why
> putting
> > > power directly to the solenoid does nothing. Does anyone know
> how
> > > the solenoid controls the brake? Does power on turn the brake on
> > or
> > > off? I do have the schematic wiring diagram and if anyone cares
> to
> > > take a stab at the answer to the question, I could email it.
> > >
> > > Thanks in advance,
> > >
> > > Keith Clark
> > > clarkfamily5@c...
>
>
>
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