No Ground calibration LEDs without the finger!

Early June 2011 I purchased Full ArduPilot Mega kit. After assembly it didn’t start correctly. I’ve traced the problem/workaround to the “ATMega1280 SPI/ISP port”. If I touch my finger to the outside two pins, I think SPI_PPM PPM_RST and GND, after about 5 seconds the 3 LED flash. Then in another 7 seconds or so I get the solid amber light and the stabilization toggle is effective. The servos will respond to aircraft or board motion. I’ll try to include a picture.

I don’t want to fly with this unit until I get a handle on this problem. But manual mode has always seems to work. And I doubt an airborne reboot will work.. unless I can add a finger to my airplane?

I’ve tried various power supplies, battery/BEC and to re-solder these pins. To test for a bad connection or cracked board I physically twisted it without touching the pins. No help. Even after 10 minutes the LEDs will not start flashing. My next course of action would be to de-solder and re-assemble.

But before I do this can someone tell me:
  • Did I find the correct pins from the Schematic, PPM_RST and GND?
  • If I put an oscilloscope on these pins at startup any idea what I should see? Should either my assumed PPM_RST and GND voltage spike/change?
  • In other forum posts I saw some interesting issue with ground on the board. Could this be related, ground is floating so it can’t boot correctly?

Using an oscilloscope on the two pins in question the LEDs will not flash with the finger trick. But I do see a spike of say 2V on the GRD side. No change on PPM_RST (stays around 5V).

Using just a volt meter I took the following readings of relevant pins. Maybe someone can check their readings?

For 4.88V input before finger:

0.00V –-o  o—4.62V
0.57V –-o  o—0.00V      <---Fwd
4.62V –-o  o—0.00V
______________
  edge

ATMega1280_problem_pins.JPG

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