Re: BP retrofit yaxis drive burnup- follow-up FIXED!

Well Guys I finally found the most recent bug. There was an
apparently defective terminal block on the x axis Gecko. After much
exchanging of parts I finally isolated the block, cap or wires.
Once the block was change everything operates the best yet. I have
rapids that are scary and no stalling. Sure feels good, I just hope
it will last!!

Keith

--- In CAD_CAM_EDM_DRO@yahoogroups.com, Jon Elson <elson@p...> wrote:
> Keith Clark wrote:
>
> >Ron, we need to compare notes to see if there is a common
pattern.
> >Mine takes some time to burn also, but I hope my problem was
having
> >the relay to turn off and on the powersupply on the DC side
instead
> >of the AC side. Now I can't get the x axis to move properly...
I
> >am going to drop to half winding mode and lower current to see if
> >that helps in the long run.
> >
> >
> If these Gecko drives last several months, and then die, I would
suspect
> it is
> a heat related problem, or possibly the current inrush is
degrading the
> internal
> capacitor. It takes so many inrushes to wreck that cap, and then
the
> uncontrolled
> voltage spikes destroy the power FETs. If these problems are all
on systems
> using a relay on the DC side, then that seems like the diagnosis.
If
> some of these
> recurring failures are on systems without the relay in the DC
side, then
> heat of some
> sort has to be it. It has been noted by several people that the
> internal cap
> in the Gecko drives runs very hot if even half a foot of wire runs
> between the main
> filter cap and the drive, and no external cap is used right
outside the
> drive.
> Most of the pedestrian caps are rated for a few years life at 85 C
core
> temperature.
>
> (My PWM servo amps have a fairly expensive 2.2 uF film capacitor
in
> parallel with
> the internal electrolytic cap for exactly this reason.)
>
> Jon