I also have had the X6 board act a little weird in a triple DQG tiny 4th. Thought it was my wiring, so I made up a new board and installed it. Everything seems fine but one little bug. When I ramp to the top (turbo) the light blinks twice and shuts off. Im running NarsilM with a attiny85 on the X6 board. If I double click to turbo, it works fine.
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I have both boards the (X6, A6) and have used the attiny85 with NarsilM on both. From what I can tell the boards are identical, except the X6 has the attiny25 and the bleed resistor. All the other components look the same and in the same layout on the board. I have pics of both boards here.