ebay power supply

[Mad Professor]

The lowest I have tried taking the PSU down to is 20volts.

I have been running the TB6560 board at 24volts fine unto my old psu gave up.

I would like to run how much voltage as possible to gain the extra speed out of the stepper motors.

I am slowly going to work my way upto 30volts.

I don't know how much, or if I will get any extra speed out of the stepper motors going from 24 to 30volts.

[ecat]

Cool.

Remember to make some allowance for the peek voltage generated by the motor when the driver stops driving, heh. There is a thread around here somewhere with more details. There's also a thread relating voltage to stepper speed.

[Bodge]

From all the great work done a lot earlier (Many thanks guys)... we could calculate the replacement for R34 this way :-

Given that the PSU spec says "If the PSU is out of regulation then Uout=42.8+/-0.5V DC."

Taking the potential divider made from R34 and R33 is 9K1 and 1k with a +/- 1% tolerance

Applying 42.8V to this divider gives us a Junction voltage of 4.238 +/- 1%

Calculated by (R1(1k)/(R1(1K)+R2(9.1K))* 42.8V = V divider = (4.238V)

So rough calculations for 49V +/- 0.5 we need a resistor R2 of 10K561 or 10.561K (which ever standard you prefer)

The nearest we I could get with standard values (1/R1)+(1/R2)+(1/R3)=(1/Rtotal) was (1/22K)+(1/22k)+(1/270K) = 10.569K or 10K569 (which ever standard you prefer)


Thus this should give an output voltage of 49.025 +/- 0.5V eg +/- 1%


To change R34 for the 3 parallel resistors this was my process.

Warning make sure the PSU has been off for a good time as the PSU capacitors hold High voltages for a considerable time 400v DC is a skin splitting voltage and quite a Deadly!! thing to touch.

Remove the 5 outer screws, remove the cover, Unscrew the top board another 4 screws, disconnect the connector connector on the end unscrew the two screws holing the grey i/o connector disconnect the mains link connector and the other 4way connector

Remove the two PCBS.

Un screw the two screws holding the Heat sink down unscrew the screw that you can reach on Diode de solder the other diode remove the heat sink.
De-solder R34 replace it with the new resistor made from 2 x 22k 1/4W 1% and the 270k 1/4W 1% resistors connected in parallel re-solder R34 Re-assemble in reverse order...
Now to test it.. the result of this change gave me an output voltage of 48.9V very slightly out from my calculated value but well within the +/- 1% tolerance on the resistors used.

excuse dyslexic spelling


pictures to follow.

[Swarfing]

This may help and save you having to open it up

[Bodge]

Yes that is a nice way to avoid opening it up.

Unfortunately when I bought the PSUs I also bought the stepper drivers & Stepper Motors .. from Arc Euro Trade (bought with redundancy pay out )

Anticipating being to OLD to get a new job.. to allow for automating part manufacture for a start-up a business. 3 years later I now need to make parts without spending much.

The stepper controllers I have are 50V max supply..

I'm building a

CNC 1.2m x 600 CNC for cutting PLY and MDF.

a CNC type lathe for drilling and cutting 15mm PTFE bar. It would be nice to be able to do 5mm or 6mm bras studding as well but think it will not be man enough to do that.
I have the Seig micro lathe but this can not take a feed through bigger than 10mm diameter so maybe this could be automated for Brass studding.

An Aluminium cutting CNC based around a SEIG X0 micro Drill/Mill is also under construction the starting Time and Precision Ltd 3 axis x 55mm/2.20inch cubed aluminium positioning stage 0.00125 resolution on X & Y at 200 steps or 0.000625 Resolution @ 400 steps. x,y,z. Table needs to be sped up its threaded drives are very fine think it was for a microscope originally.

I have a 300mm x 300mm CNC for cutting PLY and MDF. for PCB engraving its OK it can cut as it cut its own T slot Bed but its far too "SLOW".

Picture of all these bits and bobs bodgeitquicktools.blogspot.co.uk