The subwoofer’s power LED turns green for one second, then immediately shuts off and repeats. Service Manual Diagnosis: The protection circuit is active. The manual directs you to check the output transistors for shorts (Q101, Q102, Q201, Q202 on the amplifier board) and the main filter capacitors (C106, C107 - 4700µF/50V). Often, a shorted channel causes the power supply to crowbar.
Are you looking to locate a specific for the amplifier board or the power supply? logitech z906 service manual