3 . If the power supply load capacity of poor load capacity is poor, boot, power only to the motherboard , floppy normal power supply when connected to the hard disk, the CD-ROM , because of inadequate load capacity, may cause the screen goes white and does not work. Turn on the power to check , there may be for these reasons : heat leakage Zener diode , rectifier diode damage , damage to high-voltage filter capacitor , transistor and good operating point is not selected . If the transistor operating point for the selection of a good state , you can exchange each transistor oscillator circuit to increase the gain , or transfer large transistor operating point .

 

4 . If no DC output power within the blown fuse , the fault may be in the front part of the transformer primary winding. At this time , you can replace the fuse powering experiments conducted . If the AC power , fuse has burned black , then prove that the AC input circuit has a short circuit , the fuse can be added at the end of the AC input rectifier bridge ends , and directly connected to AC power , and then turn on the power , if the regulator power fan rotation is normal, and tests for each DC output voltage is normal , then the fault site in the AC filter circuit.