Centroid Community CNC Support Forum

I'm pretty confident that I'll be OK with direct rectification. The photo above is of the original SWI Prototrak drive (one for each servo). There's no transformer prior to the bridge rectifier as far as I can tell. I am curious as to the ferrite ring that the yellow and blue output leads to the servo pass around. Generally isn't that to block AC ripple and noise? Does the design of the ALLIN1DC not require these? (I'm still kinda searching for a reason my servos buzz so bad holding position; if it's not entirely Kd tuning related).

At any rate, I'm on hold until my higher voltage rating caps arrive so I can rework the power supply and ALLIN1DC board.

Since my Vari-drive belt sounds like it might have a bad spot in it, I guess I'll use the downtime to tear into it and work up a solution to convert it into a fixed ratio poly-vee drive.

What MFD ? capacitor are you using after the rectifier?
The capacitor smooths out the DC pulses from the rectifier, this smooths out the DC for the allin1dc to use for the servo motors. 12000 MFD is required for good smooth DC supply voltage.

Keith, I appreciate the personal follow up about the power supply. I sent you an email; please check your inbox when you get a moment.

Dean,

Newark has a screw terminal 12,000uF@350V cap in stock that might work:
http://www.newark.com/nichicon/lnc2v123 ... nsku=false

I can't get to my cap to easily measure the to easily measure the terminal spacing. But this one is 76.2mm diameter with 31.8mm lead spacing.

Cheers,

Tom

dean, hello. all ya got to do is un solder those caps and replace them with high voltage units of the same mfd or higher. just do a careful job and not overheat the traces on the pc board and don't make any solder wiskers that will short anything out. once updating the 6 year old allin1dc board with the new caps high voltage rated capacitors this will allow the allin1dc to run up to 180 VDC rating.
This upgrade will then allow you to use 110 VAC directly rectified (using the centroid cap board). you can do this as long as the servo motors you plan on using have a voltage max rating higher than the cap board output.

And since you have an old cap and bridge combo with a low voltage cap.... this is also and easy upgrade and all you have to do is use a higher voltage capacitor (250 VDC or higher , 12,000 mfd + recommendd) and retain the centroid capboard to generate the servo motor power without the need for a step down transformer. you don't necessarily have to have a capacitor with the exact bolt pattern found on the centroid cap board you have... it is quite simple to put terminal studs in the cap board holes and run wires over to the capacitor that you want to use with the cap board. you can do all this yourself for under $80 worth of parts. here is some reference documentation about DC power for servos and how it all works. http://www.centroidcnc.com/dealersuppor ... ds/269.pdf

terminal spacing is 1.125"

tblough wrote:Dean,

Newark has a screw terminal 12,000uF@350V cap in stock that might work:
http://www.newark.com/nichicon/lnc2v123 ... nsku=false

I can't get to my cap to easily measure the to easily measure the terminal spacing. But this one is 76.2mm diameter with 31.8mm lead spacing.

Cheers,

Tom

tblough wrote:Dean,

Newark has a screw terminal 12,000uF@350V cap in stock that might work:
http://www.newark.com/nichicon/lnc2v123 ... nsku=false

I can't get to my cap to easily measure the to easily measure the terminal spacing. But this one is 76.2mm diameter with 31.8mm lead spacing.

Cheers,

Tom

Thanks Tom. The rectifier board has a spacing of 1.125". I ended up finding a new Cornell Dubiler 450v 12,000uF on eBay for 42 bucks. It too is 76.2mm diameter with a 31.8mm terminal spacing, but is about 9" tall. It doesn't fit my cabinet layout as nicely as the original did due to being so much taller, but the price was bearable. I machined some copper straps to adapt to the rectifier board's terminal spacing; it was about the same amount of work as it would have been to remote mount the board and attach flying leads, and it looks cleaner.

nice solution, thanks for posting!

I read the whole thread...and then it died.
Curious to how this project is getting along?
Any updates?
Marty

The build portion is done, servos need tuning and the final calibrations for the encoders. I need to scrounge up the 600 bucks to buy the centroid software, then I'll use the 2 hour team viewer credit and have people who actually know what they're doing tune the servos. I started, got frustrated, and shelved it for the time being. Summer is short and busy in Minnesota, I'm working on a garage addition currently. Oh, and I need to buy and install braking resistors for the VFD, it trips out too easily when decelerating. It boots up, homes and jogs fine, but the servos are "buzzy" while holding position. If tuning doesn't solve that, I will be dissapointed.