Electronics > Projects, Designs, and Technical Stuff
ATmega2560 board overheating any idea's
HendriXML:
I recently purchased two ATmega2560 pro boards. One is working fine, one seems to be overheating.
The picture is of the faulty one. The board seems to connect via usb just fine, but after 20 seconds or so. It quits. At that time the lower left part of the board (where the regulators are) is very warm.
With the naked eye nothing special can be seen, but also on the photo I can't see anything unusual. What could be drawing this much power?
I can ask for a refund, but it could be more learning full to fix it myself.
I haven't done any probing yet, but if I had to make a wild guess, I think the 3.3V regulator is misbehaving.
HendriXML:
At the usb connector I see something that might be bridging the two bottom pins. Will make a close up shot from that section later. But seems unlikely that that could be the cause.
Psi:
Which one of the two regs are getting hot, the 3.3 or 5.0?
Try erase the chip. (to confirm it's not a short happening from code enabling an output which is shorted high/low etc..)
mariush:
The usb connector seems a bit misaligned. It almost seems the USB OTG ID pin is shorted to the GND (last two pins).
1117 regulators are known to oscillate in some situations ... most regulators in the 1117 regulators require a capacitor on the output with ESR between 0.1 ohm and 1 ohm ... these boards use ceramic capacitors that have esr lower than 0.1 ohm
It wouldn't hurt to desolder the output capacitors on each regulator (if i were to guess the big ceramic cap below the fuse and one of the two ceramic capacitors below the two resistors marked "220") and replace them with 10..100uF 6.3v or higher electrolytic capacitors.
You could always pour some sanitary alcohol or isopropyl alcohol on the board and turn it on and see where the alcohol evaporates the fastest.. that could be a shorted component. The regulator being hot could be a side effect of another component on the board drawing a lot of power.
magic:
Don't try to program anything unless all voltage rails are verified within norm.
And of course start with checking voltage on all rails.
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