On Sun, 01 Mar 2009 06:46:41 +1100, Franc Zabkar
wrote:

On Fri, 27 Feb 2009 21:30:06 -0600, Steve put finger to
keyboard and composed:

On Fri, 27 Feb 2009 18:46:54 -0600, Steve wrote:

Looks like I'm SOL. The traces each go through a 33 ohm resistor into
pins 3 & 4 of the uC. I imagine the prom got corrupted in the surge.
It has an EEPROM port, I bet if someone could flash it it'd work fine.
Oh well, I haven't tried the remote yet. This one was kind of fun,
the board was a PITA though, not meant for rework.

Steve

Well, after some probing, it looks like it might not be wiped out
program. The divider input is 3.3V, but the output is 3.5V when open
circuit. The only thing else connected to the circuit is the uC. It
looks like the uC pin may be pulling the divider a little high causing
all the buttons to shift up, causing the higher ones to not work, and
the lower ones to be shifted one over. What is curious, though, is
that the menu button has its own pin, and it doesn't seem to work.
The menu button is only high or low, no divider output. When high, it
is pulled up to 3.5v as well, instead of 3.3v.

Why not install a buffer between pin 2 and the switch commons? You
could use a 3.3V rail-to-rail op-amp wired as a voltage follower. I've
"repaired" faulty I/O pins on uCs using similar methods. It appears
that the Menu button is unrecoverable, though.

- Franc Zabkar

Good solution, shouldn't take more than a few parts & I could probably
just glue them to an unpopulated section of the board. This was kind
of a botched repair anyway, I had to guess at equivalent parts and the
board was damaged during the rework. Oh well, can't win them all.

Thanks,
Steve