The reasons for this failure are as follows: G5Xservice manual download site
 G5Xservice manual download site
1. May be the power board vice power supply didn't work, there is no 5 v output power to A board; G5Xservice manual download site
 G5Xservice manual download site
2. A plate of 5 v power supply branch load with short circuit, CPU power supply, light is not bright. G5Xservice manual download site
 G5Xservice manual download site
Repair process: G5Xservice manual download site
 G5Xservice manual download site
1. Measurement of power level before no element is short circuit, level after the original or short circuit. G5Xservice manual download site
 G5Xservice manual download site
2. Electricity measurement vice 300 v power supply is normal, but there is no 5 v output. G5Xservice manual download site
 G5Xservice manual download site
 G5Xservice manual download site
3. Disconnect the P55 plug, 2 or 5 v needle of P55, failure in P (AC) on the board, vice power itself has a problem. G5Xservice manual download site
 G5Xservice manual download site
4. 310 V electricity measurement IC501 1 foot, about 4 feet voltage 2.3 V, show level before the work is not normal, 4 feet feedback voltage is low, normal should be about 6 V. G5Xservice manual download site
 G5Xservice manual download site
5. Check 4 feet about circuit component, found ZD503 regulator tube leakage, replace the 8.2 V voltage regulator tube, power is normal.G5Xservice manual download site