Failing power supply- Nearly all modern electronics uses a 'switched mode power supply.' They are more efficient, also much more prone to failure but offer the added benefit of being designed so a 'downstream' fault will cause the supply to enter a cyclic state to avoid setting fire to your home. The supply itself will also cycle if it has an internal problem; once again, to prevent destroying itself or anything dependent on its outputs. Supplies built a couple decades ago could only do this by blowing a fuse and there are conditions that can occur that would not blow the fuse but would allow overheating and further damage as well as fire. The most common failure is of electrolytic capacitors which sometimes will show their illness by causing a bulging top or depositing a crystaline trace around their base. Often though, they show no outer signs of failure but their value can shrink to tenths of a percent of the specified due to poor seals and defective chemicals. These can only be found through measurement with a capacitance meter with a DF (dissipaton factor - loss) capability. They will be in size from ~ 3/8" to 2" in height, ~1/4" to 1 1/4" in diameter, cylindrical, perpendicularly mounted on the board. They will have markings on their shrink-wrapped sleeves (color can be any) and range from ~ .1 to several hundred uFd. with voltages from 3-4 volts to hundreds. Power supplies are often mounted on a separate board (since they are often outsourced) so if you are adventurous, take the back panel off and take a look.
Answers & Comments
Failing power supply-
Nearly all modern electronics uses a 'switched mode power supply.'
They are more efficient, also much more prone to failure but offer the added benefit of being designed so a 'downstream' fault will cause the supply to enter a cyclic state to avoid setting fire to your home.
The supply itself will also cycle if it has an internal problem; once again, to prevent destroying itself or anything dependent on its outputs.
Supplies built a couple decades ago could only do this by blowing a fuse and there are conditions that can occur that would not blow the fuse but would allow overheating and further damage as well as fire.
The most common failure is of electrolytic capacitors which sometimes will show their illness by causing a bulging top or depositing a crystaline trace around their base.
Often though, they show no outer signs of failure but their value can shrink to tenths of a percent of the specified due to poor seals and defective chemicals. These can only be found through measurement with a capacitance meter with a DF (dissipaton factor - loss) capability.
They will be in size from ~ 3/8" to 2" in height, ~1/4" to 1 1/4" in diameter, cylindrical, perpendicularly mounted on the board.
They will have markings on their shrink-wrapped sleeves (color can be any) and range from ~ .1 to several hundred uFd. with voltages from 3-4 volts to hundreds.
Power supplies are often mounted on a separate board (since they are often outsourced) so if you are adventurous, take the back panel off and take a look.