VF-3 Low DC buss voltage

[JACKOFTRADES]

Its a 95 vf-3 my dc buss voltage seems to be low in the machine diagnostics screen at about 145 it is bleeding off for some reason all the way down to 92 volts I verified that my board that supports the drives is good what else could cause this.

[Loose Nut]

Check your incoming voltage and the multi tap transformer in the control. If they do not match the output of the transformer could be too low causing the low buss.

If it is good, Disconnect the buss output to the drives and disable the axis in parameters. If the buss is stable after that you have an axis bringing it down. If it still bleeds off then that servo distribution card is going out.
On some cards there is a potentiometer labeled A-D. This adjustment pot. sets the output voltage to the motor interface and it will end up on your screen. You want your screen voltage to match your actual DC Buss voltage.

Loose Nut.

[Thread Ripper]

Check the voltage at the Bridge Rectifier located on the servo distribution card( the one with the big capacitors) it should match up with what you see in diognostics, if it does not there is a pot there called A to D, you can adjust that till what you see on the screen and what you have at the rectifier are within a couple of volts, if it keeps bleeding down the capacitors are not holding the charge, and you will probably need to replace the servo distribution card.

[JACKOFTRADES]

I have adjusted the pot to 155v It keeps fluctuating up and down I will disconnect the axis and see if it still fluctuates.

[JACKOFTRADES]

The power keeps fluctuating even with the axis unhooked my distrubution baord must be bad, I appreciate the advice on trouble shooting this problem thanks guys.

[Loose Nut]

No problem Jack!

Loose Nut

[Thread Ripper]

Good luck

[serviceman]

Nte 22k ohm 2 % 2w 322 2w nte 78463 the resistor on this board goes bad i think its the third from the right below the pots red red orange i think. you can usually see the led light getting dimmer you can change this resistor and fix the board. if you ohm it out or look closely you will probably see cracks in it or that it is getting burned up