Open the machine back cover the power supply voltage measurement in addition to the + 12 V low voltage of 1.5 V the rest are normal, a closer examination reveals the main circuit boards several wet printing, further observation is found that the wet printing by the board of electrolytic capacitor, electrolytic capacitor near to wet printing circuit board all new and clean with alcohol, boot sound normal but I can't color image, overhaul related parts were not found the problem, suspected circuit board by the electrolyte corrosion leakage, therefore to circuit board use detergent to clean (when cleaning puts plate and high frequency head) to remove the electricity ram dry commissioning, then image voice all returned to normal. We take too much this kind of machine, fault datong less variations are using this method to repair, Hitachi 2518 electrolytic capacitor leakage yes common fault. Hitachi 747 and 757 video also had a similar problem, fault phenomenon tone sound and image, instability, at this time as long as the servo IC near the electrolytic capacitor can eliminate a fault after all new and clean.4Svservice manual download site