RE: [CAD_CAM_EDM_DRO] Help, continuing to burn drives

Ron,

This is a cross post (from the mach1mach2cnc group) of what I sent in answer
to Keith's question. The more I think of it, the more this seems to be
related to Windows sending code out the parallel port when starting up. The
suggestion below about the start-up procedure I use with an additional
switch may cure this.


I'm kinda thinking on the fly on this one.

In order to get the fuse to blow, your Gecko is drawing too many
amperes somehow. A "surge" on the line side is unlikely to force
this (unless you have somehow created a floating ground which
the "enable" relay is clearing). Assuming this, something is going
on with either the signal to the Gecko doing something vastly wrong
(don't know if it can, but say telling the drive to do the impossible
as a pulse from the CPU an boot up). Personally, I've noticed things
like this, so I have isolated the startup by using a pushbutton to
engage my enable relay after MACHx is started. I'm pretty sure
that's the problem. Only other thing I can think of is a bad spot in
your motor which is shorting out on startup, but that's unlikely if
it works otherwise.

What I do is use a contact on the "enable" really to latch it with
the "Start" push button and use the E-Stop button to disengage it
(N.C. in series with the coil). After I push the button, I then hit
the "Start/Reset" button of MACH to tell the software it's OK to run.

This way, (while it does create an additional operation of pushing
the "start" button), any boot up "artifacts" are ignored by
everything. I also end up with a situation that, while MACH can
initiate a software E-Stop, when I hit the E-Stop push button, the
Hardware has no choice but to stop regardless of the state of the
software.

I just took a look and the circuit I'm talking about is posted as a
schematic under the files section of the mach1mach2cnc group, under pendants
in my folder.
Download the JPG file (it's almost illegible when viewing with Yahoo)
and look at the upper right hand corner of the drawing. The
schematic is a little confusing because I am using multiple relays in
different parts of the setup for ENABLE, but the concept I explained
in my previous post should be able to be pulled from this.

Let me know if you need more help,
Jeff


-----Original Message-----
From: Ron Kline [mailto:godsone@...]
Sent: Sunday, April 03, 2005 4:49 PM
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: Re: [CAD_CAM_EDM_DRO] Help, continuing to burn drives


Mine just did the same thing Friday afternoon , for the second time in 6
months , the machine was running fine I shut it off for lunch and when I
turned it on after lunch the 4 amp fuse blew so I replaced it , blew again I
disconnected the motor to see if it was shorted and it still blew the fuse
.
This is exactly what happened 6 months ago and Mauriss replaced the drive
because it was only 2 months old .
I have checked the stepper with a meter and it checks fine just like the
rest of the steppers !
Both times it was the same axis Z .
???????
Ron

Keith Clark wrote:

>Hi Guys, My bridgeport retrofit continues to burn Gecko drives. It
>happened just a few minutes ago when I powered up the machine and
>computer. The powersupply was plugged in but the relay controlling the
>powersupply was off. When I hit the button in the software to turn on
>the relay the Gecko immediately burned as did the protecting fuse. It
>always happens on the y axis when I first start up. It never seems to
>happen while running the machine. This is at least the fourth time this
>has occurred. Each time I think I have found the problem but alas, no.
>The last time was early Feb and then again
>last week. A new Gecko was installed thursday. It makes no sense
>why the thing would run for a month with no trouble. It think
>everything is installed correctly but there must be a powersurge from
>the powersupply when the relay first turns on. Is this a possibility
>and is there a way to protect from this?
>
>Thanks for any ideas!
>
>Keith Clark
>
>
>
>
>
>

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