Measuring basic normal + B + 113 v voltage, switching power supply with no problems. Measuring R536 Ω (56), R519 Ω (6.8 k / 2 w) on the terminal voltage of about 0.95 V. That protection circuit has action and protection. Disconnect short R536 end of commissioning, but found a grating of narrow; Measuring D522 (MA4108) negative voltage of the normal around 9.0 V to 11.5 V, analysis for line flyback voltage is too high, leading to the protection circuit. Key check C538, C539 after shutdown, C540, C509, C511, C516, C518 flyback capacitor, is C511 (0.0082 u F / 1.25 kV) capacity loss, cause line flyback period shorten, the flyback voltage rise, caused by a protection circuit action and protection.d3Lservice manual download site