choke coil that is inserted to raise the +B voltage during6-6. P Board
15 kHz input mode. Q2519 is the switch to add the S-
shape capacitor for 15 k and 30 k to the circuit, and isThe P board consists of the PWM circuit for horizontal
driven by Q2522 and Q2523. The control signal fordeflection system and for high voltage system, the + B
switching these horizontal frequencies is supplied frompower supply for high voltage output, protector circuit,
IC2502 (D/A converter).degauss circuit and heater circuit.
..... Vertical Output Circuit1. PWM Circuit for Horizontal Deflection and
The vertical output circuit consists of IC2504 and itsHigh Voltage Systems
peripheral circuit.The PWM circuit for horizontal deflection system has
The vertical output signal is generated by inputting thealready been described. The PWM circuit for high voltage
V. drive signal that is output form IC2503 pin-29, tosystem controls length of the ON period of the high
IC2504 pin-1 where it is amplified. The V. centervoltage PWM output that is output from IC504 pin-13.
position is controlled by inputting the V. DC signal thatThe ON period is controlled by the error output that is
is supplied from IC2503 pin-28, to IC2504 pin-7. Theobtained by comparing the reference voltage that is
vertical deflection amplitude and the vertical centergenerated by the shunt regulator IC504 with the high
position are controlled by IC2503.voltage detected output that is output from FBT pin-12
The vertical feedback pulse is generated by wave-which is the voltage obtained by dividing the high voltage
shaping the V. flyback pulse with R3505, R3506 and(HV) with resistors.
D2524, and by inputting it to IC IC2503 pin-30.For your reference, the input signal that is used as the
reference of horizontal defection and the high voltage
..... H CENTER Circuitsystems is the HD signal that is output from IC2503 pin-
The H CENTER control is performed by converting the21. The HD signal is locked to the input signal of the
DC voltage level of IC2502 (D/A converter) pin-7 tomonitor. (When there is no input signal to the monitor, it
electric current by IC2518, Q2516, amplified by IC2507,synchronized with the free-run frequency.)
and by super-imposing an appropriate DC current uponThere can be a case that the horizontal output circuit and
the horizontal deflection current through L2504 (HCC).the high voltage output circuit are damaged because they
The power supply for IC2507 uses the floating powercannot follow the sharp change of input frequency when
supplies that are HC+, HC- and HC N as describedfrequency of the input signal is changed or when input
before.channel is switched. In order to prevent the horizontal
output circuit and the high voltage output circuit from
..... Protector Circuitdamage, IC502 reduces the ON period of the horizontal
The D board (P2) has the three protectors that are H.and high voltage PWM output to their minimum (by
PROT, V. PROT and H+B OVP. The H. PROT is thedecreasing the + B voltage so that the horizontal deflection
protector that is activated when the horizontal deflectionsize is reduced to minimum and high voltage is decreased
is stopped. It detects existence of the collector pulseto the lowest voltage) when IC502 receives the frequency
with IC2514, IC2515, D2519 and C576 after the collec-change information from IC2503 pin-37 (DTC: Dead Time
tor pulse is divided by C2556 and C2557.Control) in the D board. The ON period is controlled until
V. PROT is the protector that is activated when thethese circuits are locked o the input frequency slowly with
vertical deflection is stopped. It detects existence of thesome time constant in order to prevent these circuits from
V. out waveform after the V. out waveform is rectifieddamage.
and smoothed out by D2523 and C2578.IC502 also has the built-in HD drive output circuit that
H+B OVP is the protector that is activated when the + Breceives the HD input signal and is locked to the input HD
power voltage has increased by some defects. It detectsfrequency. Phase and ON time of the HD output signal is
the + B voltage after it is divided by R2552 and R2553.determined by the voltages that are applied to pin-22 and
Operating point of the protector is about 65 V.pin-21 respectively. In this monitor, this HD drive signal
is also used as the drive signal of te high voltage output
circuit.
6-6BVM-D9H1U/D9H5U/D9H1E/D9H5E/D9H1A/D9H5A |
ACEC
