M2 servo drive power supply (PU31) not working

So I have been trouble shooting issues with the servo drives (TRA31 and 41) for a while with no progress on a VQC 20/50B but just recently had the issue change (not sure if I did something to make it worse or if I am eliminating issues which is allowing me to find new issues).

It used to have intermittent drive faults but recently changed. The machine started faulting out on power up (x axis fault), so I swapped the drive (which had already been done once before). The machine now powers up and comes up ready, and drives don't fault, but when you try to move an axis, the control will show that it is moving but nothing actually moves. Then the machine will eventually fault because of servo lag.

So I started looking upstream, there is power to the servo drive power supply (PU31) but P and N appear to only have a couple of volts on them (does anyone know what voltage they are supposed to at?). I tried resetting the breakers, checking the fuses with no change. I then swapped in a different power supply from a parts machine (I don't know if it was working), still no change. Also if I turn the power supply main breaker off the machine still functions the same, which continues to lead me towards the idea that either there is an issue with the power supply or something that controls/turns it on is not working.

Sorry for the novel, any thoughts?

Thanks

The P and N should be fairly high voltage when working correctly, 200 volts DC maybe? (Actual voltage will be at least as high as the ratings for the servo drives and motors).

I know the newer Mazaks with the MDS drives utilize a 300 volt DC bus, feeding 200 volt drives and servo motors.

ToolCat Greg

cnctoolcat said:

The P and N should be fairly high voltage when working correctly, 200 volts DC maybe? (Actual voltage will be at least as high as the ratings for the servo drives and motors).

I know the newer Mazaks with the MDS drives utilize a 300 volt DC bus, feeding 200 volt drives and servo motors.

ToolCat Greg

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That is what I was thinking/expecting.

Considering that I have the same issue with 2 different power units I think that there must be something blown/tripped up stream.

sudsy55 said:

I really don't know but would the P and N only have voltage out when the servos are running or is that constant voltage?

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I believe that the power supply supplies a "constant" voltage on P and N to the servo amps and the servo amps are what turn power on/off/switches direction to the servos.


So I have solved the issue related to the power supply not coming (still have other issues in the drive system). 24 votls is supplied to the servo amps from the NC, and then at least 1 servo amp passes that 24 volts onto the control board on the power supply. In the process of testing and swapping servo amps I ended up in the scenario where all of the servo amps in the machine didn't have the 24volt jumper connected that supplies voltage to the power supply. I added the jumper and it powered up without a problem, now still have to fix the motor overload issue on y axis.