The reasons for this failure are as follows: ZTJservice manual download site
 ZTJservice 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; ZTJservice manual download site
 ZTJservice manual download site
2. A plate of 5 v power supply branch load with short circuit, CPU power supply, light is not bright. ZTJservice manual download site
 ZTJservice manual download site
Repair process: ZTJservice manual download site
 ZTJservice manual download site
1. Measurement of power level before no element is short circuit, level after the original or short circuit. ZTJservice manual download site
 ZTJservice manual download site
2. Electricity measurement vice 300 v power supply is normal, but there is no 5 v output. ZTJservice manual download site
 ZTJservice manual download site
 ZTJservice 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. ZTJservice manual download site
 ZTJservice 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. ZTJservice manual download site
 ZTJservice 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.ZTJservice manual download site