I created a PCB for my newest Arduino project and its driving me mad by now. I am through several PCB variations and tried connecting to it (via FTDI first - then) via ISP but I fail every time and in each revision.

Tested all the pads/pins for a short - everything seems ok. On each board I soldered only the barebone components (2x 22uF, 1x100nF caps, 10k resistor, XTAL) to test it. I can often see tiny sparks between the pins when I trying to flash the chip - but I cant find any shots.

I am trying connecting my PCB through ISP with another arduino (ISP sketch on it / + #define old wiring).

I am pretty sure that C2 is not needed - but it also does not work without it.

I am very open to any ideas how to get this done because it is getting very expensive :). Build about 10 different boards now and can't find the issue.

Uploaded the latest schematic and some PCB pics. enter image description here

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closed as unclear what you're asking by Dave Tweed Dec 6 '18 at 12:45

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    \$\begingroup\$ "I can often see tiny sparks between the pins when I trying to flash the chip" this should not happen. Any parts that were on a board where it happened should be considered dead. Perhaps you have a very wrong power setup, or a severe ESD situation - is the air very dry where you are? Are you working on carpet? \$\endgroup\$ – Chris Stratton Dec 5 '18 at 20:54
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    \$\begingroup\$ Your regulator caps are many orders of magnitude too small \$\endgroup\$ – Chris Stratton Dec 5 '18 at 20:56
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    \$\begingroup\$ By the way, your schematic is much harder to read because you seem to do everything upside-down. In my region of the world, ground is usually down (so GND is always drawn downwards), and I read things from left to right (so signals flow from the left to right). I understand that the reading direction varies between countries, but at least the ground is always down. \$\endgroup\$ – pipe Dec 5 '18 at 20:56
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    \$\begingroup\$ Build a new one without the regulator and try powering it with the 5v rail of the ICSP programmer Arduino and no other power supply. Have that Arduino in turn powered/run via USB through a hub by a computer you can afford to lose. Have no other connections to any part of the system. Or even use something like github.com/adafruit/Standalone-Arduino-AVR-ISP-programmer that requires no computer connection at all, and use a quality phone charger to power the ICSP Arduino and target. \$\endgroup\$ – Chris Stratton Dec 5 '18 at 20:58
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    \$\begingroup\$ 22uF? you mean 22pF, right? \$\endgroup\$ – Tom L. Dec 5 '18 at 21:24