K8062 hardware problem

Kits PC Related Projects
1

Hi,
it’s my first “creation” with solder and electronic componets, so I didn’t expect it would work at the first attemp, but I’m really stuck with this problem and I need a little help to solve it.
I mounted all the components, checked the polarities and all the weldings: they’re ok, so I probably burned something…
In standalone after pressing the button power led lights up, then, after nearly a second DMX led starts to flash. After 2 flashes it turns off followed by the power led delayed of about a second.
It’s all… my Velleman interface functions for 3 seconds… The pc don’t even recognize it!
I’m a little worried about this strange behaviour, I wonder what’s wrong.
If you’ve got any idea, please help me.
Thanks.

MoX

2

Have you measured the VDD voltage of IC2 pin 20. Is it 5V in test mode?
Do this 5V voltage appear if you connect the unit to the USB connector of the PC when the battery is removed? There should be 5V. Check also the voltage of pin 14 of IC2 (VUSB voltage). It should be about 3.3V.

3

Checked today: pin 20 is always between 4.80V-4.85V but pin 14 seems grounded…
so I cut and rewired pin 14, C7 and R9 but nothing has changed, I’ve got the same problem.