USB-BUB Overheating

Problems uploading, serial connections, BUBs, P4, FTDI cables, etc
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jackdesert
Posts: 2
Joined: Tue Apr 12, 2011 9:41 pm

USB-BUB Overheating

Post by jackdesert » Tue Apr 12, 2011 9:58 pm

I just assembled a sanguino kit (see sanguino.cc), and connected a new USB-BUB to it. With everything connected, like this:

Computer == USB Cable == USB-BUB == Sanguino

the chip on the USB-BUB gets hot very fast. Almost hot enough to burn my finger, and it gets that hot in just five or ten seconds. The green "power" LED on the Sanguino lights, but very dimly. The red "debug" LED on the Sanguino blinks a couple times, then I think it goes off.

On the other hand, If I plug in everything but the Sanguino, like this:

Computer == USB Cable == USB-BUB

then the chip on the USB-BUB stays cool. I'm hoping my BUB is still ok, as I've only had it connected for ten or twenty seconds at a time like this. Perhaps there is a solder short on the Sanguino between VCC and ground? Any suggestions?

Jack

paul
Site Admin
Posts: 733
Joined: Mon May 12, 2008 4:19 pm

Re: USB-BUB Overheating

Post by paul » Wed Apr 13, 2011 8:04 am

Jack,

You almost certainly have a short somewhere on the Sanguino. Check resistance with a meter between ground and power.

I'm suspicious though that the FTDI chip on the BUB is overheating instead of the polyfuse. This means that it's the 3.3V line that is drawing the current.

Are you using BUB II or original BUB? If using the original BUB, make sure that you are using one of the rows of header pins closest to the edge of the board for the female header. The first two rows have the 3.3 V line in the two rows closest to the FTDI chip - If you soldered the female header in there - it would short the 3.3V line when you plug it in - and cause symptoms similar to what you describe.

If you are using BUB II make sure you aren't setting two incompatible options - with the shunt and solder jumper say.

Probably everything will be fine once you find the short. If not - we'll send you a new board.

Paul

jackdesert
Posts: 2
Joined: Tue Apr 12, 2011 9:41 pm

Re: USB-BUB Overheating

Post by jackdesert » Wed Apr 13, 2011 9:20 am

Paul,

You are right. I have the original BUB. I did the aesthetic thing, late at night of course, and used the third row in for my 6-pin female header. So the 3V line was indeed grounding out. To fix it, I just cut the trace on the 3V line, and everything stays cool now.

I also figured out why my Sanguino power LED was so dim--the wrong resistor value was used at the Sanguino's R2.

Jack

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