Open the rear cover, found a leakage on the circuit board, circuit board with alcohol is clean, work with blower again. Check projection tube, found that liquid rubber valve up to the largest outward mouth, analyse the reason of leakage should be internal stress. Remove the rubber valve, needle tube removed part of the liquid (until you can turn the rubber bonnet just pressure, liquid has no leakage). If the three shots have leakage, same treatment methods, and tighten the screw around. If also appear leakage, need to replace valve sealing ring and rubber. N7Tservice manual download site
 N7Tservice manual download site
When cleaning circuit board has been found to have a few components pin corrosion, the cleaning after each repair welding is good. Therefore machine without drawing, see the line label, after startup check CPU power supply 5 v voltage, press the power button CPU output voltage is normal, but the whole machine. Check the power supply load circuit, all the later found manager J6920 breakdown. After replacement J6920 still not boot, check line of excitation voltage output, check no 9 v power supply voltage. The 9 v power supply by IC801 r09 (278), check the circuit input feet and IC807 (KA78R12) output terminal connected, the connection circuit. With wires connected after the commissioning, everything was normal. N7Tservice manual download site
 N7Tservice manual download site
 N7Tservice manual download site
Later analysis, could be corroded metal hole, lead to 9 v voltage instability, she also damaged by incentive disorder.N7Tservice manual download site