Re: servo brake problem

Thanks Hugh! I appreciate the education. Now I have some ammunition
to trace the problem farther! Do you think I can test the solenoid
safely by placing power briefly directly to the wires at the solenoid
itself?

Keith Clark

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Hugh Prescott"
<hugh345@a...> wrote:

> see inline comment
> ----- Original Message -----
> From: "Keith Clark" <mail@t...>
> 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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