Hi,
I have a number of assembled PCBs (see PDF schematic attached) which have been checked for components/assembly but don't seem to work.
It is an insanely simple circuit. All it does it takes a audio signal and drives two sets of LEDs and a small coil. All three through separate current sources. Nothing more than that.
To save battery, there is power switch Q1 which is turned on/off by inserting or removing the jack that supplies the audio input signal. That is done through the ENABLE signal on the switch contact in the jack (pin 10 of the jack).
Whether I use the battery only (connected to J2) or the USB 5V supply or both, what happens is that when I insert the jack, VDD goes to GND and remains there after I unplug it. There seems to be some short circuit or overcurrent but cannot see anything wrong with the schematic.
BTW R20 is 1K and R21 is 10K (not 0R as shown in the schematic... they were set to 0 just as placeholders for tuning later).
Any idea anybody?
Thank you