[Skler]

Trouble shooting yourself & looking for the obvious, or using the "Shotgun"
approach:




If the power supply rail voltages are low or even totally gone, you may be
able to fix the supply yourself.

If it's a modular switching supply, see if it would be worth it for you to
buy a new supply from the manufacturer and put it in yourself.

If the supply is of the traditional analog type, you should be able to
trouble shoot it with a volt meter. Common failures in such circuits include
blown fuses (chassis mount, on-board type, or "in-transformer" fuses), bad
voltage regulator IC's or transistors, bad rectifier diodes or bridge
rectifier modules, burnt up & open circuit lands, leaky capacitors (usually
in older equipment). Regulator IC's or transistors are the most common
failure. Remember that if there's a blown fuse or burnt up & open circuit
land/trace, it was most likely caused by the failure of some other
component, and often when one component fails it will cause a cascade of
failures. A popular technique for electronic repair when the parts in
question are relatively cheap is to use the "shotgun" approach, in which
simply all of the key electronic components are replaced. e.g. Main
regulator IC's & transistors, rectifier diodes, zener diodes and filter
capacitors. Resistors that have been subject to too much heat are usually
easy to spot, since they will be discolored and sometimes misshapen; you can
usually measure them in circuit as well to see if they've opened up or
shifted in value significantly, though modern resistors are less prone to
failure. To purchase the parts you need, check out the on-line electronics
catalog stores like Mouser, Allied, DigiKey and Newark.



Skler