Problems with stepper driver (L297 and L6203)

[MagooT]

Hello dudes, i have assembled a board using this schematic
http://netikka.net/maggot/bipolar.png

Here's the board layout
http://netikka.net/maggot/bipolar_brd.png
X2-1 is +5v
X2-2 is +15v
X2-3 is GND

X1-1 is DIR
X1-2 is STEP

M1-M4 are the motor outputs


However it doesn't work.
I have measured about every pin using my oscilloscope but the only strange thing i found is that the outputs of the L6203's (pin 1 and pin 3) are high all the time, when i step it slowly (using jog in Mach3) i can see some small flickering around 14-15volt, but i assume it should switch between high and low.

Since i can't find anything wierd on the board, i'm asking if anyone can spot any errors in the schematic or board layout, i have checked the board about 10 times for solder bridges or stuff like that so i don't think that's the problem.

Any ideas what to look for would be nice, since i have no idea what might be wrong with this.

If you need more info just let me know, and sorry for my bad english
Greets
// MaggoT

[markcomp77]

I found one error... look R6 & R7 on your design



R6,R7 need to be connected to GND and sense->L6203[10]
look -> http://forum-cnc.pl/index.php?topic=55.0

[MagooT]

Thanks for your help.
I have fixed the problem now but it still won't run.

Another go with the oscilloscope shows that pin 1 on both 6203's now switch between 0 and 15volts, but pin 3 switches between 0 and 5 volts i can hear a small ticking sound from the motor when im jogging but it doesn't move.

When i measure between GND and motor outputs M1-M4 i just see a blinking line at 10 volts on the oscilloscope.

[markcomp77]

Another go with the oscilloscope shows that pin 1 out1 on both 6203's now switch between 0 and 15volts, but pin 3 out 2 switches between 0 and 5 volts i can hear a small ticking sound from the motor when im jogging but it doesn't move.

out1 and out2 should switch between 0 and Vs

1)
data sheet of l6203 is:
Vs Supply Voltage --> min=12V typical=36V max=48 V
its better to use higher voltage...
power supply - on AC24V trafo (DC output about 32..33V)

2)
use new L6203... and make new tests

When i measure between GND and motor outputs M1-M4 i just see a blinking line at 10 volts on the oscilloscope.

make output current measurements... current of winding

[MagooT]

I just found the problem (embarassing) if you look at my schematic OUT1, BOOT1 and OUT2, BOOT2 are the wrong way around on the motor outputs, so i switched them and now it seems to work thanks a lot for your help.

[markcomp77]

I just found the problem (embarassing) if you look at my schematic OUT1, BOOT1 and OUT2, BOOT2 are the wrong way around on the motor outputs, so i switched them and now it seems to work thanks a lot for your help.

do you think about...



making of STEP=1/2 better?
to have equal ful step and half steps...

[MagooT]

I'm sorry, i don't understand what you mean, i'm not good at reading schematics what does it do?

[markcomp77]

what does it do?

it change Vref (=>output current) for half steps...
because of this => torque of motor on full steps and half steps will be equal
because of this => half steps will be more precise

[MagooT]

Ok, thanks.

Another question, i'm trying to run a small motor from a printer (don't have any other specifications for it other than "10 ohms", unfortunatley), and it get REALLY hot just after a few seconds, so i assume i must recalculate sense-resistors or something? Because the chopper isn't lowering the current at all, can anybody explain how to do this?

[markcomp77]

Ok, thanks.

Another question, i'm trying to run a small motor from a printer (don't have any other specifications for it other than "10 ohms", unfortunatley), and it get REALLY hot just after a few seconds, so i assume i must recalculate sense-resistors or something?

yes...
but better is to regulate Vref of L297
look there -> R23

Because the chopper isn't lowering the current at all, can anybody explain how to do this?

use potentiometer (R23) to set Vref
look on any L297/8 driver - make the same...

[MagooT]

Thanks, i googled around a bit and read about vref, this is what i came up with:

Schematic: http://i20.tinypic.com/2emdkx0.png
PCB: http://i23.tinypic.com/28lg9c8.png

This allows me to adjust Vref between 0 and 1.7 volts, should work great.
Guess it's time to etch a new board an try it out

[xinzc28]

Hi Magoot, I made similar driver.

My 10 ohm resistor is always get to smoke because of excess heat.
Do you have this problem?