[dougputt]

Hi everyone

I just moved up from Boss 5 with Mach to a Fadal VMC15. Really like the machine but on startup or when a axis trips I get a really bad buzzing from the three relays in the top r/h of the rear cabinet. If I jog and reset the axis it goes away. But the noise is obviously not something that should be happening. Also I switched the taps and jumpers for the voltage from 440V to 210V at the transformer. I can't find any other changes that need to be done in the manual but am I missing something?

Doug

[carbidecraters]

We had this same problem it was a couple of small relays that jarrred loose after moving. They look like ice cubes! You can start the machine with the door openand find the relays that are clicking away and then power down and remove and reinstall them. Sometimes they only need a push.

[Al_The_Man]

I would confirm the voltage present on the coils when picked up, AC inductive devices do not tolerate much in the way of under voltage.
Al.

[Neal]

Since you made a major change in the applied voltage I would recommend redoing the Servo Loop Gain.

Neal

[dougputt]

Ok, looks like it's just the top relay thats buzzing away. When I push on it slighlty (with a piece of wood) it stops buzzing. Or of course when I reset the axis it stops.

Doug

[dougputt]

thanks for the replies,

Neal, where would I find the Servo loop gain adjustment procedure in the maintenance manual?

Regards
Doug

[Al_The_Man]

When I push on it slighlty (with a piece of wood) it stops buzzing.
Doug

This is usually an indication the contactor armature is not seating properly or low coil voltage.
Al.

[dougputt]

Thanks Al, I will check the voltages.

[dougputt]

I'm just trying to find the voltages and the amplifier setup in the manuals.

[dougputt]

Anyone have any information on setting servo loop gains as Neal mentioned?

DP

[dougputt]

Servo loop gain adjusted and no joy, relay is still buzzing like a .....

[Neal]

IT may b that the motor is causing the relay to buzz. Try touching up the COMP pot on the amplifier and see if you can sttle it down.

Neal

[dougputt]

Hi Neal

Yes I've already tried adjusting the Comp pot but no joy. It seems the relay only buzzes when I first start up the machine or when it gets a axis fault. Once I hit the estop and then restart axis the relay is quiet. I'm going to try chasing down what voltages i'm getting at the relay or try swapping the clip diode.

Doug

[dougputt]

Ok, I'm messed up believe the relay thats buzzing is for the spindle brake. If i type in s100 it will stop buzzing....

[fadalserviceguy]

have you checked the green relay on the 1100-1 bd. - it's part of the e-stop circiut - try subsitution with a black relay just to isolate it - i doubt that all three amp are that far out

[Al_The_Man]

If it is the relay armature, the motor or drive should have nothing to do with it?
You mentioned three relays buzzing, if so this really points to low coil voltage, did you measure the coil voltage when they are picked up?
This should tell you immediately if it is a low voltage problem.
Al.

[TRIMI]

call kevin german 316-990-7373 he will help you by phone he is really good he fix my machine he used to work fadal wichita,ks

[dougputt]

Thanks for all the replies guys,

Al, no sorry it is actually only the top relay that is buzzing, i've attached a picture of the one in question. In the original post your right I did say it was the three relays but I've since narrowed it down to just the top relay. I would replace it if I could verify that it's at fault and not something down the line, I find it strange that there is no clip diode or snubber across the contacts? Or am I just missing them?

[Neal]

dougputt--
The relay you are looking at appears to be in the main power circuit and not an ything to do with the axis amplifiers. Check tghe 3 phase power going into the amp chassis and also it looks like you have a wye/delta spindle setup. Check out that circuit as well.

Neal

[fadalserviceguy]

HI DOUGPUTT -NOW THAT I SAW THE PICTURES THESE RELAYS ARE PART OF YOUR Y/D SPINDLE CONTROL AND THE RELAYS ARE RATED FOR 120 VAC OPERATION - YOUR VOLTAGE SHOULD BE BETWEEN 90 VAC TO 130 VAC BEFORE IT WOULD CAUSE THEM TO BUZZ - IT'S POSSIBLE THE THE CONTACTS ARE BURNISHED AND WILL NOT ALLOW THE RELAYS ARMATURE/COIL TO SEAT PROPERLY - ANOTHER CHECK IS TO MAKE SURE YOUR SPINDLE MOTOR IS NOT LEAKING TO YOUR MACHINE'S GROUND - YOU WILL NEED A MEGA-METER FOR THIS AND IF YOUR NOT SURE OF WHAT YOUR LOOKING FOR BE CAREFUL AND CHECK SPINDLE MOTOR LEADS ONLY AFTER THEY ARE ISOLATED - IT NOT UNUSAL TO REPLACE THESE RELAY AS THEY HAVE A DUTY CYCLE LIFE AND THE NEW REPLACEMENT WILL ONLY HAVE TWO RELAYS- LET ME KNOW HOW YOU MAKE OUT