I'm building BC Audio's x0xi0 with custom PCBs & custom enclosure (the complete kit).
I've tested VCO1 & 2, VCF, VCO sync, Xmod, etc., on a 'scope so I know the analog circuit is good. I'm having problems with the digital section.
I'm at the step of testing the VCA by programming and playing a pattern. I was able to get some (sporadic) function of Pattern Edit mode, enough to figure out where the Mode encoder is pointing. I can't program a complete pattern, etc., but I first want to figure out why I have Step and sequencer LEDs lighting up when they shouldn't be. When I power it up, several of the LEDS light up and remain on (usually 75% of the left side LEDs). This happens whether the microcontroller is in its socket or not. I was told that the step sequencer LEDs should not be lit when powered on without the microcontroller in place. I want to solve the LED issue before I sort out why the sequencer is not working properly. I don't know if the two issues are connected.
I've tested voltages and they're good. All of the sequencer ICs are placed in proper orientation and are getting 5V. I've scanned the PCB both sides with a magnifying glass. I've tested continuity of LED_latch, SPI_CLK, SPI_IN and they're good. (I don't know how to test for continuity of SW_LATCH.)
At this point, when I turn it on without the microcontroller, 75% of the LEDs and tempo LED remain on until I touch pin 32 of the microcontroller socket, then they all go off. If I sweep my finger across pins 1-20, then all of the LEDs turn on, sweep again and they turn off.
Can anyone help me?