Grating appear flashing, accompanied by shrinkage phenomenon, the main reason is caused by a + B voltage fluctuation. When inspection, measuring + B between 112 ~ 126 v voltage fluctuations. To distinguish the fault is in the power circuit and the load circuit, temporary operation tube oSOI collector, with a 60 w bulb after a false load, connected to the power and found that the brightness of the light bulb in the flashing, shows that the fault is in the power supply circuit itself. Dk7service manual download site
 Dk7service manual download site
Measuring Q802 collector voltage, found that the voltage fluctuations between 16 and 32 v, check Q802, found that the collector and emitter has a short circuit phenomenon, caused by fault is Q802 control. After replacement, troubleshooting.Dk7service manual download site