Obviously, make sure that you are well insulated!
Do not attach or disconnect anything.
This would be the running man episode 51 eng sub full case if you wanted to determine whether a supply was good or wanted to use the supply for other purposes.(Probe) - In 1 / 2 K, 25 W Unmarked diodes are 1N400X (where X is 1-7) / or other general purpose silicon rectifiers.The technique I recommend is to use a high wattage resistor of about 5 to 50 ohms/V of the working voltage of the capacitor.PC power supplies (as well as most other switchers) need a minimum load on 5 and possibly ios 6 user guide pdf on 12 as well.The boost diode often includes the buck-regulators "ringing-choke" in the "net inductive component" that it recovers energy from!Check the bias coming from the feedback.Safe PC power supply loading PC power supplies are often ideal for other purposes but the required loads represent wasted power.This is more likely to happen with multiple devices plugged into the same gfci protected outlet especially if they are controlled by a common power switch.The -5 V output is derived from the -12 V output using a 7905 regulator.However, the cause of many problems are immediately obvious and have simple fixes - the blown chopper transistor or dried up main filter capacitor.This is basically banks of 2N3055's (for.3V) and 2N3773 (for 12 V upwards) in series with low value power resistors than can have their conduction varied and current monitored by other circuitry.
Typically, a reference circuit on the output side senses the primary output voltage and turns on the LED of the opto-isolator when the output voltage exceeds the desired value.A lower wattage resistor (compared to that calculated from V2 / R) can be used since the total energy stored in the capacitor is not that great (but still potentially lethal).A college textbook for power electronics courses.Secondly they should tell you what voltage or resistance to use to replace the opto-isolator (or transformer) for that load.I used to work for one such company, they repaired all of Sun's power supplies from throughout Europe.In any case, you will have the satisfaction of knowing you did as much as you could before taking it in for professional repair.