If you want to check the hot section in a power supply, always use the one hand ‘rule’ so that it would not complete a path for current to flows through your body just in case if you were to accidentally touched a live connection or cable. If you are tired and weak, do not repair any electronic equipment or else you might end up causing more problems for the equipment by replacing a wrong component. Take a break and come back to tackle the problem when you are fresh again.
Always use original part numbers for replacement when dealing with components in the critical section such as the fuse area. If the fuse rating is 3 ampere, then you must replace it with the same value which is 3 ampere. Sometimes a slightly higher ampere such as 3.15 ampere may be acceptable. Do not use a 10 or 15 ampere for replacements otherwise fire may occurred due to over current because the fuse may not melt.
The main filter capacitor with a high capacitance and voltage must be installed in the correct location. The positive marking at the capacitor must be inserted to the hole where it printed (+) and a negative marking to (-). A wrongly installed filter capacitor can cause the filter capacitor to explode and may injure your face if you are near to it. In some severed cases, the blown capacitor may burn the power supply as well.
Lastly, don’t because of this information explained above scared you away from repairing a power supply. Just make sure you understood the power supply repair safety first and things will become easier. Understanding the safety procedure above can protect your life.