Switch energy storage power supply disappears defect type

What happens if a switchmode power supply is unplugged?

Careless troubleshooting of a line powered switchmode power supply can result in severe electrical shock or electrocution. This is potentially more lethal than the high voltage section of a TV or monitor due to the high current availability. Even the charge on the main filter capacitors with the unit unplugged can kill.

What happens if a switchmode power supply fails?

During testing of horizontal deflection circuits or switchmode power supplies, particularly where the original failure resulted in the death of the HOT or chopper, overstress on replacement transistors is always a possibility if all defective components have not be identified.

Does a switchmode power supply degrade?

Nothing really degrades in a switchmode power supply except possibly the electrolytic capacitors (unless a catastrophic failure resulted in a total meltdown) and these can usually be replaced for a total cost of a few dollars.

How stressful is a switchmode power supply?

Startup is the most stressful time for a typical switchmode power supply. The output filter capacitors as well as the load must be driven while the input voltage is changing - possibly wildly. With careful design, these factors can be taken into consideration. Not all power supplies are designed carefully or thoroughly tested under all conditions.

Can a power supply be repaired without a schematic?

Even without schematics power supplies can be repaired. The same type of circuitry repeats itself. Older power supplies often used the TL494C pwm IC, newer use the UC3842/3/4/5 series driving MOSFETs. Some older still used the NE5560, SG3524 etc., many didn't use a PWM IC, but instead discrete components.

What is a switch mode power supply?

Switch mode power supplies are commonly used in computer and other digital systems as well as consumer electronics - particularly TVs and newer VCRs though audio equipment will tend to use linear power supplies due to noise considerations. You will find SMPSs in: PCs, workstations, minicomputers, large computers.