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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

Please clarify your specific problem or add additional details to highlight exactly what you need. As it's currently written, it’s hard to tell exactly what you're asking. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

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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