Open the chassis, observe the filament is not bright. Of each main power source of for measuring the output voltage of 0 v, and rectifying the output 300 v normal, CPU 5 v power supply is normal. The judge fault in the main power supply circuit, but carefully check all the key elements are not abnormal, load also corrosive to short circuit phenomenon. Thick film integrated circuit IC601 main power source of for measuring voltage (DP308P) of each pin, except 1 foot, the rest all the feet of 0 v. After substitution IC601, fault is still. To a careful study of the machine drawings, found IC602 start feet (3 feet) is controlled by the start of the 5 v switching power supply output voltage. Direct measurement of microprocessor power T661 1 foot external D663 cathode voltage, also to 0 v. D663 cathode disconnect, again measurement: D663 negative extremely 17 v. Measuring D663 anode ground resistance is almost O Ω, judgment of peripheral components have a breakdown or leakage phenomenon. After carefully check, found that the electrolytic capacitor C663 breakdown leakage. Replace a 10 mu of 50 v/F is the capacitor, switch on again, display normal boot, troubleshooting.5uuservice manual download site