UPS Repair
Battery charger
Transformer
Inverter circuit
Troubleshooting
The UPS works only for a brief time
Testing the battery charge circuit
Testing the battery itself
The inverter transistor are blowing

AT power supply repair
How to recognize an AT power supply
Rectification and doubler circuit
Switching transistors
Output diodes
The start-up circuit
The regulator circuit
How to test a AT power supply without the motherboard
The correct way to use the load lamp

ATX power supply repair
Differences between AT and ATX power supply
The PS-ON function
How to test a ATX power supply without a motherboard
The stand by power supply

Motherboard Repair
Parts description
The internal PWM power supply
How the chipsets communicate to each other
The serial port
The clock generator of the processor
Good motherboards that do not work
Weak points
Soldering techniques
SMD and BGA  techniques
Troubleshooting


HDD study

How it works
Data recovery at software level
Some tips to recover data at hardware level