Lets start with some very basic steps to diagnose the board. Please refer to the assembled board photo and schematic to perform the following steps:
- Put a jumper on J6 between pins 2 and 3 i.e. "Load" and "+5" (refer to "Board-Reference.jpg", Reference 1)
- Check the orientation of all three chips in their sockets. Make sure the "notch" is toward the top on all chips (refer to "Board-Reference.jpg", Reference 2)
- Apply power from a known good source (fresh batteries or a power supply)
- Measure the voltage from GND to V+ of the power source. Make sure it is within operating parameters (i.e. no less than 7.5v and no more than about 30v)
- Measure the output of the 7805 regulator U3 between GND pin 2, and output pin 3 (refer to Board-Reference.jpg, Reference 3). It should be a steady 5v and the regulator should stay relatively cool i.e. not get "piping hot".
- Remove the jumpers from J1, J2, J3 and (if present) J7 (labeled "+5" and "RST").
- Using a VOM (or preferably an oscilloscope) to measure the voltage from Pin 13 (PA0) on U1 (the ATTiny microprocessor) and GND. The voltage on this pin should move between 0v and 5v as the chip cycles through its patterns. On an oscilloscope you should see PWM patterns on occasion as some "fade" patterns are run.
Repeat step 7 for pins 12, 11 & 10. If you DO NOT see changes in voltage levels on these pins, the microcontroller may be damaged. If you DO see changes in signal on these pins, move on to the next step.
- Using a VOM (or, again, preferably an oscilloscope) measure the voltage from V+ to pin 18 of U2 (the ULN-2803 Darlington array, refer to the Schematic-8b.jpg). As in step 7, the voltage on this pin should move between 0v and 5v as the chip cycles through its patterns.
Repeat step 8 above for pins 17 through 10. If you DO NOT see changes in voltage levels on these pins, the ULN-2803a Darlington driver chip may be damaged. If you DO see changes in signal on these pins, move on to step 9.
- Check the orientation of the LEDs in J5. Use a VOM to make sure that the LEDs were not inadvertently installed backwards.