The machine to discharge pressure type window circuit. To turn it off, C870 stored by the accelerating voltage filter capacitance voltage to accelerate the discharge of the anode high voltage, eliminate shutdown window. Z8aservice manual download site
 Z8aservice manual download site
So shutdown window may be produced by C870 failure. In addition, the luminance channel, brightness clamp is not normal, also affect the effect of eliminating shutdown window. Z8aservice manual download site
(repair method) Z8aservice manual download site
(1) with a first pf / 2 2000 kv capacitor in parallel on the C870, observe the shutdown window, the results did not change, explain C870 is good. Z8aservice manual download site
(2) 100 pf / 16 v to shunt capacitance on C305, observation window, elimination results window completely eliminated. Explain blanking clamping capacitance failure, after shutdown IC501 14 feet voltage can't keep. 14 feet voltage is inversely proportional to the tube cathode voltage, thus reducing the shutdown tube beam current, make the anode high voltage discharge effect is not good, have to turn it off. Z8aservice manual download site
After replacement C305 100 u F / 16 v machine back to normal.Z8aservice manual download site