Service manual

CA-21
Deflection Control
CRT Protection
CRT protection is provided for the CA in circuitry off the vertical amplifier. In case of a damaged IC2100
or a shorted CX2107 for example, this circuit will prevent damage to the CRT by shutting the microproces-
sor off. In turn, this action shuts down the television receiver. The circuit is composed of C2109, DX2102,
DX2103, R2120M, R2121, R2122M & R2123. Pin 11, the pump-up, of IC2100 emits a pulsing wave-
form. DX2102 rectifies this waveform to a DC voltage across C2109. After passing through the voltage
divider network formed by R2121 and R2122M, the voltage can be found on pin 13 of IC6000 and should
meter between +3.6 and +5.1 volts. Should the voltage be outside this range, CRT protection will trigger.
If the CRT protection circuitry is triggered at power on, the television will turn off in 3 seconds. If this
occurs, it will be necessary to reset the microprocessor before the television will turn on. Resetting the
microprocessor may be accomplished by removing AC to the set for a couple minutes.
R2120M
R2121
R2123
R2122M
C2109
DX2102
DX2103
+5 VSB
To CRT Protection
Pin 13, IC6000
Pin 11,
Vertical Amplifier,
IC2100
<<Figure CA-20>>
Part Location Part # Notes
TX3204 095-04372-01 Refer to Service Manual
095-04601-01 for Corresponding Models
QX3203 121-01383 All Models
IC2100 221-00992-01 All Models
<<Table CA-3>>