| 摘要 |
The method and apparatus for controlling heater voltages to the heaters of a CRT includes sensing the presence of pulses at an input of the heater control circuit (800). In another embodiment, a DC level change is sensed at an input to the heater control circuit. When pulses are present (e.g., retrace pulses), or the DC is at the appropriate level, the heater control circuit reacts to provide a stable 6.3V to the cathode heaters. When the pulses are not present or the DC level is not appropriate, the circuit reverts to a low-conducting mode where insufficient voltage is provided to the heaters of the CRT for normal operation. |
