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Author Topic: Servo with Gecko320 blowing fuses  (Read 5400 times)

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Servo with Gecko320 blowing fuses
« on: March 25, 2009, 10:19:49 AM »
I posted this on the yahoo group but yahoo is slow slow so I thought I would post it here. Hope no one minds.

Been a few years since I have done anything with CNC so I have to relearn it again.
Here is my setup. Lathe with steppers on X and Z. Servo on the A axis. All motors have 500 count US Digital E2 encoders.
Breakout board is Campbell on one Parallel port. On other pp is a Sound Logic Encoder board. All cables are hooked up per the two boards specs.Triple checked.
X and Z work fine. I get encoder feedback in Mach3. The plugin dll don't work but that's a problem for later. One thing at a time.
The servo worked once. I turned the limit up and grabbed the motor to see what kinda torque it had. Well it was strong until it blew a fuse. Now it blows fuses
anytime I jog.
Any ideas. My first foray into servos.

Donny
Re: Servo with Gecko320 blowing fuses
« Reply #1 on: March 25, 2009, 10:23:28 AM »
Move the suspect Gecko to another axis.  If it still blow fuses, then send it back to Gecko for (free) repair.

Regards,
Ray L.
Regards,
Ray L.
Re: Servo with Gecko320 blowing fuses
« Reply #2 on: March 25, 2009, 10:26:32 AM »
I just put a new one on there. No change. I guess I can try again. Might have had two bad ones.

Donny
Re: Servo with Gecko320 blowing fuses
« Reply #3 on: March 25, 2009, 11:59:25 AM »
what size fuse are you using? the gecko 320 is rated 20 amps.
Re: Servo with Gecko320 blowing fuses
« Reply #4 on: March 25, 2009, 01:07:02 PM »
5 amp. Thats all I ran on steppers in the past. I forgot the Servos take bigger fuses.  
Its working now with the 5am and limit is turned all the way up. No load though. The Servo is a Home Shop CNC Nema 34 8.6 amp cont. So yeah 5amps was to low. Its hard to get back into this when one has been away so long.

Donny

BClemens

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Re: Servo with Gecko320 blowing fuses
« Reply #5 on: March 25, 2009, 05:50:52 PM »
I believe you have your 320's adjusted wrong ( gain and damp) and that will blow fuses! How well I know   ::).... Start with the set-up of the G320's from the beginning and do not be tempted to 'see' where another axis that works well is set - that does not necessarily work with another motor. Set as per the installation notes from Gecko. You'll be fine! 

Beginning is: LIMIT - 1/4 to 1/2 full scale; GAIN - fully off and; DAMP - to 1/4 of full scale. Turn system on and motor will 'sing' or dither between encoder counts. If the motor blows a fuse now at these settings, reverse the motor leads and try again. If fuse OK then input some step pulses with Mach3 and your mouse. The DAMP and GAIN work very much together and adjusting one will require adjusting the other as well - at least with the older 320's like these. They seem to 'learn' so be slow with adjustments and try the motor for a period before adjusting more - keep notes...

Go with the set-up carefully as is posted on the Gecko site. I just bought a new one because of the same issues and sent the 'bad one' back to be repaired and there was nothing wrong with it. The settings were wrong!

Good going with this....they are hardy devices and protect themselves quite well so don't give up on it too soon. I used many fuses in this same dilemma but finally learned...   

Bill C.   
Re: Servo with Gecko320 blowing fuses
« Reply #6 on: March 25, 2009, 10:29:10 PM »
5 amp. Thats all I ran on steppers in the past. I forgot the Servos take bigger fuses.  
Its working now with the 5am and limit is turned all the way up. No load though. The Servo is a Home Shop CNC Nema 34 8.6 amp cont. So yeah 5amps was to low. Its hard to get back into this when one has been away so long.

Donny

Donny,

    Sounds like you've fused the DC power lines into the Geckos?  Bad idea.  If the fuse blows under load, you stand an excellent chance of blowing the Gecko.  Fuse the AC line into the power supply, not the DC into the Gecko.  The Gecko will protect itself.

Regards,
Ray L.

Regards,
Ray L.

BClemens

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Re: Servo with Gecko320 blowing fuses
« Reply #7 on: March 26, 2009, 05:35:43 AM »
I use 3.5 amp fuses in similar sized servos - they work fine. Maybe my servo motors are over sized for the job and never require their designed current? Setting the limit above or below that current still has no effect on blowing fuses....I found that the GAIN and DAMP settings have more effect on blown fuses. Besides, if the LIMIT was set too low, why were fuses blowing?

These fuses are positioned after the Geckos in line to the servo motor, not in the power input lines. Maybe that is the difference here.

Only attempting to help. I see no reason to correct anyone on this board since the offerings are intended for insight in setting up and using these machines, etc., etc.

Bill C

« Last Edit: March 26, 2009, 05:42:06 AM by BClemens »
Re: Servo with Gecko320 blowing fuses
« Reply #8 on: March 26, 2009, 07:36:15 PM »
I do have the power supply fused on the input line. I also have fuses before the G202's and the G320. So looks Like I need to move the lines around and put those fuses between the geckos and the motors?

Donny

Offline comet

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Re: Servo with Gecko320 blowing fuses
« Reply #9 on: March 27, 2009, 10:48:54 AM »
Donny,
 I believe that putting the fuse between the motor and the drive is just about the worst thing you can do.
It can blow the rdrive if there's a sudden loss of impedance on the out put.
  Why are you fusing the servo's? there is an adjustable current cut out built in.that is by far the best way of
dealing with it.
   Tony