- Thu Dec 29, 2011 4:03 pm
#137580
So I've got a MegaShield that I just took out of its bag to start assembling. Like many others, I'm disappointed.
For starters, the board won't sit flat because of the USB connector. This means there's going to be a gap between the female headers on the MEGA and the MegaShield. Is that really the way it's supposed to be?
Also, there seems to be a possibility of a 5V to GND short. That 5V bus runs directly over the USB connector. The metal USB connector housing is, as it should be, grounded. So the way this board is designed, you've got open hole directly connected to 5V that are literally pressed against a big ground connection. My multimeter tells me there's about 1k of resistance between 5V and ground, but I imagine this could be even less depending on how yours happens to be manufactured.
I realize that a 1k resistor to ground is hardly a disaster (although it will use some minute amount of power), but the only reason there's 1k of resistance there is because the connection is just resting there. If something were to push on the PCB or if a tiny wire clipping or metal shaving fell in the right spot, you'd have a short.
Am I missing something or are these problems that others have had to deal with as well? I know I can fix both of these with some electrical tape and careful mounting, but I was hoping I could assemble my project without reaching for a roll of tape to prevent a potential short.
For starters, the board won't sit flat because of the USB connector. This means there's going to be a gap between the female headers on the MEGA and the MegaShield. Is that really the way it's supposed to be?
Also, there seems to be a possibility of a 5V to GND short. That 5V bus runs directly over the USB connector. The metal USB connector housing is, as it should be, grounded. So the way this board is designed, you've got open hole directly connected to 5V that are literally pressed against a big ground connection. My multimeter tells me there's about 1k of resistance between 5V and ground, but I imagine this could be even less depending on how yours happens to be manufactured.
I realize that a 1k resistor to ground is hardly a disaster (although it will use some minute amount of power), but the only reason there's 1k of resistance there is because the connection is just resting there. If something were to push on the PCB or if a tiny wire clipping or metal shaving fell in the right spot, you'd have a short.
Am I missing something or are these problems that others have had to deal with as well? I know I can fix both of these with some electrical tape and careful mounting, but I was hoping I could assemble my project without reaching for a roll of tape to prevent a potential short.