Philips PM3208 Service Manual page 20

3-2 3 BLOCK DIAGRAM DESCRIPTION
3.2 HORIZONTAL DEFLECTION
The TRIGGER GENERATOR receives internal trigger signals from channel A or channel B
and an external signal from the EXT BNC bus. This stage amplifies the trigger signal and
then activates the SWEEP GENERATOR circuit by clock pulses.
The SWEEP GENERATOR circuit consists of a sweep control circuit, a Miller integrator
circuit, a sweep length circuit and a hold off circuit. The sweep is initiated by clock
pulses.
The HORIZONTAL SWITCHING circuit is controlled by the TRIGGER SELECTOR and a
time selection switch. The trigger selector switch selects the input signal to the TRIGGER
GENERATOR. The time selection switch controls the signals from the SWEEP
GENERATOR. Output is conveyed to the HORIZONTAL OUTPUT AMPLIFIER.
The HORIZONTAL OUTPUT circuit amplifies the input signals from the SWEEP
GENERATOR or TRIGGER SELECTOR by means of a differential amplifier circuit and
conveys these to the CRT.
3.3 POWER SUPPLY
The POWER SUPPLY circuit is mainly equipped with operational amplifiers. Regulator
circuits are used to supply stable voltages. The high voltage for the CRT is supplied by a
feed-back DC-DC converter generating the stable — 2 kV high voltage.
3.2 HORIZONTAL DEFLECTION