After startup screen is not bright, the power indicator light is normal, can feel have high pressure, and field deflection coil can be heard the voice of the work. sp7service manual download site
 sp7service manual download site
From the failure phenomenon, the machine's power supply and basic normal line, field scanning circuit, likely fault circuit is put in apparent or tube voltage circuit. First three cathode voltage of the measuring tube, respectively in 42 v, essentially normal. Measure other pin tube voltage, the filament voltage is only 2 V (normal 6.3 V). Check for filament power triode Q604 (KSD1616), found the c, a and b are 7 v voltage, but it's only 2 v e voltage. Q604 remove the measurements found its b - e has break between, with the working current larger D880 replacement after the machine repair.sp7service manual download site