6-16
BVM-D32E1WA/D32E1WE/D32E1WU
4. Protection circuits
. H. STOP, V. STOP detection circuit
The H.DY current is converted to a voltage value by T4 and R42. The voltage thus obtained is sent to
IC501 pin-3 on the EA board and is compared with the reference voltage of pin-2. The detected voltage
is inputted to IC501 pin-3 of the EA board where it is compared with the reference voltage of pin-2.
When the horizontal deflection is stopped and the input parabolic voltage is not inputted any more, the
voltage at pin-3 becomes lower than the reference voltage so that the H. STOP output signal from pin-1
goes “LOW”.
The sawtooth wave voltage that is generated across R606 and R613 from the V. DY current is amplified
by IC550 and is used to switch Q550. Because the capacitor C553 keeps discharging as long the saw-
tooth wave is input, IC501 pin-6 voltage of EA board does not reach the reference voltage that is inputted
to pin-5. However, if the vertical deflection is stopped and the sawtooth wave is not inputted any more,
IC501 pin-6 voltage exceeds the reference voltage at pin-5 and the V. STOP output signal from pin-7
goes LOW”.
When either the H. STOP signal or the V. STOP signal goes “LOW”, Q502 of the EA board is turned off
and Q504 of the EA board is turned on that stops the HV DRV pulse. Because Q503 on the EA board is
turned on at the same time, Q505, Q506, Q508 are turned on so that the E_PROT signal goes “HIGH”.
Then the power supply circuit enters the standby state.
. Over-current protection circuit for the power supply circuit of the horizontal deflection circuit
When the current flowing in the power supply of the horizontal deflection circuit becomes larger abnor-
mally, Q702 is turned on. Q512 to Q514 are also turned on the +B. PROT signal goes “LOW”. At the
same time Q509 is turned on that sets the E_PROT signal to “HIGH”. As the result, the power supply
circuit enters the standby state.
5. Control circuit
IC7001 (sub-CPU) perform the serial communication with IC1 (system control CPU) of the BC board
using the three signals of MISO, MOSI and SCLK. As the result of the communication, IC7001 outputs
the control signals such as POWER ON, DEGUASS, H. DELAY, V. DELAY, etc., and also outputs the
result of identification of horizontal frequency. IC7001 reads the adjustment data from IC7004, IC7006
to IC7010 (EEPROM), and controls IC2001 and IC7005, and also controls IC202 and IC206 on the D
board, and controls IC710 and IC711 (24 inch models) of the PA board. The following protect detection
signals are transmitted from IC7001 to IC1 of the BK board.
H. STOP, V. STOP, +B. PROT, HV_OVP, IK_PROT, HV_OCP, G. PROT1 to G. PROT4
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