I have just completed my K8062 kit, testing both resistor values and short circuits as I progressed through the build, but having conducted the self-test with a 9v battery, the Power LED will not stay lit.
Pressing the button lights the Power LED, but as soon as I release it, the power light goes off. It looks like the latching action is not happening.
Can anyone point me to where I should look for the problem?
If you look the circuit diagram you see there signals labeled RA0 and RB6 at the pins 2 and 27 of IC2.
When the button is pressed RA0 should go high (about 4.5V). This should activate the latch function in the microcontroller and RB6 should go high too (about 5V). This RB6 signal turns “on” transistor T2 and the power on switch transistor T1 will be turned “on” too.
Many thanks for your help. When I checked the voltage on RA0 I found only 1.7v, which prompted me to change the battery I was using. With a brand new battery, this increased to 4.5v as you predicted.
With the fresh battery, the power LED now lights solid and the DMX light flashes, so I’m now on to the next phase of testing.