Need help with H-bridge motor driver board

[Nitrus]

Hi guys,

I've bought a board like this one:
http://www.ebay.com/itm/Dual-Motor-Driver-Module-Board-H-bridge-DC-MOSFET-IRF3205-3-36V-15A-Peak-30A-New/401236483976

However, I can't get it to work.

For the PWM, I have an Omega 2 with the dock and the PWM extension.
I have verified Duty/Frequency with multimeter and a cheap DIY oscilloscope.

So, if I hook up my motor to the Omega, I can control the Duty Cycle via WiFi, and I've tested this with a small motor, works fine (hooked up only through the Omega, without the driver board)
But when I hook it all up to this board, with a 12V supply on the power pins for the motors, I can't get it to work. I mean, I can't get it to work with this board either with external +12v, or with +5v from the Omega.
The instructions are vague and in Chinglish, so I'm not sure if everything is proper.

I have it set-up like in the attached image.
Can anyone be of assistance? I can't get the motor to spin at all.

Thanks in advance guys

[danadak]

If its an isolated design, eg. photo couplers in the data path, then
grounds do not have to be common, otherwise they do.

See if you can get a schematic from seller. Or worst case, do your
own, so you can troubleshoot. Also try to locate a Chinese forum
to see if you can get any info on controller chip.


Regards, Dana.

[mtdoc]

The eBay description of that board is useless. Do you need an input signal to Dir1 or Dir2 to specify direction?

[Nitrus]

The eBay description of that board is useless. Do you need an input signal to Dir1 or Dir2 to specify direction?

From what I understand, the DIR pins are just for direction, high or low. That being said, I tried running 5V across it, and also tried putting the PWM signal from the Omega on it, no dice.

I've added some images in the attachments.
The PWM signal seems to go to pins 8 and 9 of the NAND gate. No-go on the schematics, so I don't know if there's any routing underneath the chip.
From the datasheet I can see that pin 8 is 'data output' and pin 9 is 'data input'. Seems a bit odd to me to have those coupled, but that's how it is.
EDIT: I've misread the Gate chip, it's actually 74HC02D, which is a Quad 2-input NOR gate. The text I've written in the image would be wrong, that last 'D' looked like a '0' to me...
Pins 8(3A) and 9(3B) are both 'data input' .

What does the term 'data' suggest to you?

EDIT2: I added another image, where I've combined the two sides. The top (red) side routes that go under chips I tested with a multimeter...

All the MOSFETs are ST P75NF75, however some have a '&', some have a '@' at the end of the string (P75NF75& or P75NF75@)