Re: [CAD_CAM_EDM_DRO] Blown Gecko 320..Strange noises from control???

R Rogers wrote:

>Hi all,
>
>Last night I was running my mill and I heard a loud pop and I could smell something like linseed oil in front of the machine. Everything seemed fine though, then a few minutes later two loud boomps! And Z axis Gecko went into fault and Z did not work. So I investigated and discovered that the Z gecko had indeed failed and a capacitor on its board had exploded leaving an oily residue under its cover. The Gecko and heatsink were slightly warm and the Z motor was just barely warm, I was fly cutting and hardly using Z at all. Mostly X axis. So I changed the drive with A axis that I rarely use and set the Gain, Damp and Trim as they were on the one that had just ran flawlessly for a year and a half of continual use.
>
>I came in this morning fired up the control It was fine and ran all day. After 14 hours of pulling a 3/4" rougher hogging out some forming dies (heavy load but not unusually so), its been making the loud snap noise and the boomp noise. More boomp than snap though..:-). I'd say it happened about 10 times today at all different times. And after many of them I would immediately check all motor temps as well as open the enclosure and check everything for heating and everything stayed cool and the machine ran perfect all day. Nothing seemed unusually warm, there was no smoke or anything other than the noises. It has never done this before. Using a drop light I could see back under the cover of the Gecko's and there was no blackness, oil or blown anything from what I could see.
>
>Last night when I swapped out the drive, I checked carefully for chips or wires possibly shorting. I cant figure it out. Here is an outline of whats in my enclosure and I dont see how any of it could make a noise unless it fried: Transformer, EMI filter, 3-20k 100 volt Uf Capacitors, Breakout board, 3-Gecko 320's on sinks, Cooling fan, 24-volt power supply for air valve, 24 volt Air valve for coolant mist(neither were on when drive blew, Main power double pole relay. Computer with Surge supressor that also protects the power to the control. I think I may be getting voltage spikes Coming into the building as a few light bulbs throughout the shop have blown in the last few days.
>
>Pics of inside the enclosure are on the "CNC pics" group at yahoo under rogersmach. Any suggestions to what may be doing this? I'm totally stumped. The noise is definitely coming from the enclosure. I checked the voltage from the main transformer and then off the bridge rectifier and it was fine about 72 volts DC. I was thinking maybe the old transformer was shorted internally. It seems fine though.
>
>

Wow, that's quite wierd! Do you have any new electrical equipment
there? Air conditioner, refrigerator, anything?
Sometimes when electrical equipment starts, especially larger motors, it
causes a dip in the line voltage.
When the line voltage comes back up, the filter caps are somewhat
depleted, and need to charge back up.
The lights, especially fluorescents, might flicker at the same time.
(It could actually be equipment at a
neighbor's house, if they are on the same transformer.)

One other thing I can think of is if the main power switch is going bad,
and every once in a while it gets
an open circuit for a moment, then the current makes a connection again,
but the transformer has lost
excitation and has to sync to the line again. This can cause a big
"Boomp" depending on the line phase
at the instant it turns back on. The switch might get warm as a sign of
this happening. You could also
check the primary wiring for a loose connection.

It could also be the bridge rectifier may be going out. Usually, those
do no go intermittent first, but
anything is possible.

One last possibility is that one of your motors has developed an
intermittent short to ground. If so, you
will lose another Gecko soon! (I kind of doubt this, as a short to
ground will pop a Gecko pretty quick.)
However, if the Gecko supply is mostly floating, but there is a weak
ground path, maybe through the
breakout board, parallel port cable, computer, power cord anc back to
the machine's ground, it might
not blow the Gecko right away. When the short goes solid, lots of stuff
will smoke, cables will melt,
it will be a big mess. I hope this is not what is really going on.
Darn strange, I wish I could actually
hear it do it, and see what the machine does at that moment. Does it
twich at all? That might be an
indication that the DC voltage dipped at that moment.

Jon