DIY FEZ Domino

[quote]I have send the seller a question I hope he is going to answer, he is a high ranked seller, you think that if he sells bogus parts more people would give negative feedback.
[/quote]

As most folks buying parts from such sources are hobbyists, they most likely are not pushing the parts to their limits. A friend of mine who produces commercial products recently bought a load of transistors from a broker in China. Looking at them under a microscope showed scratches on the surface. They had be sanded down and re-labeled. The only way to confirm was to contact the ‘real’ manufacturer and confirm the data code on the parts.

you might still need to explore Jeff’s point about why the regulator is even running in this scenario. USB provides 5v. The regulator shouldn’t be providing power at that point, and unless your actual part is NOT a pinout replacement for the LM1117 regulator it shouldn’t be getting hot. From the schematic I note it might be worth checking the direction of D2.

Thanks Brett you are right I checked the Panda and there is nothing running through the regulator when powered by USB. It is indeed the case with my self made Domino! very strange, I checked the D2 direction and as far as I can tell it is correct, the marking on the diode is facing the marking on the board:

just like on the Panda:

Just as a sanity check I turned D2 around so the marking faced the other way, but then the board is not getting any power at all through USB, so I guess that D2 is placed correctly. Any other ideas what can cause the AMS1117-5V to get power when connected trough USB?

I’ve had a similar problem with an Arduino clone. Powered by external PS works without any problem. When USB powered the 5V voltage regulator heats up and the board draws 500mA.

The problem was a short cut under the USB connector. To much solder flows between the USB metall case and the PCB connectors.

Hi RobotFreak, thanks for you response. I have checked and double checked the USB connector and I can’t see any short cuts, the strange thing is I have now made 3 boards and they all have the same problem… so or I can’t solder :slight_smile: or there is another problem, and to be honest I have no idea anymore.

I did not read all the posts here.
But check if the crystal’s signal. Is it oscillating at 12MHZ.? This might give you another clue if your board is working or not.