[chepot]

please see the attached image.

it's stepper driver board: 2xL298 (parallel), with diodes and sense resistors, capacitor & connector.

at first I made the small one, it work well (the yellow line is correction -> i forget to connect common ground) the problem is the space is to tight for L298's heatsink and big diodes.

then I make it bigger, and the problem come...the motor now have noisy sound.

color on layout:
green = ground
red = vss (24v)
pink = vcc (5v)
blue = L298 output for bipolar stepper

where are the mistakes?

[vger]

The green line and the pink line across the bottom are shorted together at the connector. Count from pin 1 of the input connector on both sides of the board.

Steve

[chepot]

i re-check the circuit, the pink(vcc) and the green(gnd) are not shorted.
if it's shorted, the circuit will not work.

both layouts work, but the bigger layout causing my stepper motor having noisy sound.

both layouts use the same component, except diodes.
small layout use BYV27-100
big layout use UF5404 (I have tried to replace it with BYT-56M but still noisy)

btw, i replaced BYV27 diodes because it's IF.av is 2amp...can it handle 3amp?
i have tried operating the BYV27 with 3amp current, but i'm affraid it will getting hot and break

[vger]

I see, your top and bottom are not mirror image... Ok, How about your diode polarities? double check that.

[chepot]

diodes polarities are ok.
finally i found the problem, it's not on this layout.
I forget to put rc filter on sense line on the other board.

btw, thanks vger for giving time to look my layout.

[vtxstar]

The different diodes seem to be the only variable not duplicated so...

Can you post the schematic of this circuit or give a reference to it?

[chepot]

vtxstar, the problem is solved.

at first i thougt that the problem came from this board or layout.
but the problem is on the other board (my L297 & L298 are not on the same board).
on my other board (which contain L297), I forgot to put rc filter on sense line, that's why the noise appear.