If your downstream devices are buzzing or acting erratically, the A20112 filtering stage has likely failed.
Large electrolytic capacitors (e.g., 16µF to 4700µF) to smooth out voltage ripples. Regulation: For 12V DC modules, you'll often see an voltage regulator to maintain a steady output. Protection: a20112 power supply schematic
Need Help / Found: A20112 Power Supply Schematic If your downstream devices are buzzing or acting